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  • Artikel  (16.771)
  • Artikel: DFG Deutsche Nationallizenzen  (16.771)
  • 1995-1999  (13.198)
  • 1965-1969  (3.573)
  • Elektrotechnik, Elektronik, Nachrichtentechnik  (16.771)
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  • Artikel  (16.771)
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  • 1
    Digitale Medien
    Digitale Medien
    Pure high dose metal ion implantation using the plasma immersion technique (1999)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 70 (1999), S. 4359-4361 
    Details
    ISSN: 1089-7623
    Quelle: AIP Digital Archive
    Thema: Physik , Elektrotechnik, Elektronik, Nachrichtentechnik
    Notizen: High energy implantation of metal ions can be carried out using conventional ion implantation with a mass-selected ion beam in scanned-spot mode by employing a broad-beam approach such as with a vacuum arc ion source, or by utilizing plasma immersion ion implantation with a metal plasma. For many high dose applications, the use of plasma immersion techniques offers a high-rate process, but the formation of a surface film along with the subsurface implanted layer is sometimes a severe or even fatal detriment. We describe here an operating mode of the metal plasma immersion approach by which pure implantation can be obtained. We have demonstrated the technique by carrying out Ti and Ta implantations at energies of about 80 and 120 keV for Ti and Ta, respectively, and doses on the order of 1×1017 ions/cm2. Our experiments show that virtually pure implantation without simultaneous surface deposition can be accomplished. Using proper synchronization of the metal arc and sample voltage pulse, the applied dose that deposits as a film versus the part that is energetically implanted (the deposition-to-implantation ratio) can be precisely controlled.© 1999 American Institute of Physics.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1063/1.1150094
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  • 2
    Digitale Medien
    Digitale Medien
    An ultrahigh vacuum sputtering system with offset incidence magnetron sources onto a rotating substrate (1999)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 70 (1999), S. 4362-4365 
    Details
    ISSN: 1089-7623
    Quelle: AIP Digital Archive
    Thema: Physik , Elektrotechnik, Elektronik, Nachrichtentechnik
    Notizen: An ultrahigh vacuum sputtering system with offset incidence magnetron sources has been designed and developed to deposit thin films and multilayers with excellent film thickness uniformity, precise control over layer thickness, and surface and interface roughness. The unique feature of the system is that the sputtering guns are aligned at 35° oblique incidence onto a rotating substrate with a 60 mm offset from the substrate center, which make full use of the best linearity of the plasma flux at the substrate, and therefore, deposit extremely uniform thin films. Other features include, computer-controlled deposition process, capability of heating the substrate to 1100 °C, and in situ monitoring of thin-film quality with reflection high-energy electron diffraction. The performance of the sputtering system is demonstrated, and a characterization of multilayers deposited by the system using a grazing incidence x-ray reflectivity and high resolution electron microscope is also presented. © 1999 American Institute of Physics.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1063/1.1150080
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  • 3
    Digitale Medien
    Digitale Medien
    A design of a nanometer size metal particle generator: Thermal decomposition of metal carbonyls (1999)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 70 (1999), S. 4366-4369 
    Details
    ISSN: 1089-7623
    Quelle: AIP Digital Archive
    Thema: Physik , Elektrotechnik, Elektronik, Nachrichtentechnik
    Notizen: We have developed a method which can produce both pure and alloy nanometer size metal particles in a large scale. This method combines a thermal decomposition of metal carbonyls with a collision induced clustering. Metal carbonyls are thermally decomposed with a hot filament and resultant bare metal atoms undergo collisions to produce nanometer size metal particles. This method requires a very simple experimental setup even though it is a high efficiency production method. Using this method, we have produced, high purity Fe, Mo, and alloy Fe/Mo nanometer size metal particles. © 1999 American Institute of Physics.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1063/1.1150081
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  • 4
    Digitale Medien
    Digitale Medien
    Detectivity comparison between thin-film Pd/PVDF photopyroelectric interferometric and optical reflectance hydrogen sensors (1999)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 70 (1999), S. 4370-4376 
    Details
    ISSN: 1089-7623
    Quelle: AIP Digital Archive
    Thema: Physik , Elektrotechnik, Elektronik, Nachrichtentechnik
    Notizen: A novel dual photopyroelectric interference (PPEI)/optical reflectance (OR) solid-state hydrogen sensor system has been developed and demonstrated. Based on the recently developed PPE-interference technique and the variations of optical and electronic properties of Pd metal in the presence of hydrogen, simultaneous signal responses were obtained from a polyvinylidene fluoride (PVDF) thin-film detector and an optical photodiode. The dual measurement of PPEI and OR channels provides not only a more reliable sensor system, but also a powerful tool to identify the operating mechanism(s) in the process of Pd/PVDF/hydrogen interaction. The experimental results show that the detectivity and the signal dynamic range of the PPEI method are much higher than those of the OR method due to the suppression of the large base-line signal and the signal noise. The comparison of PPEI and OR results reveals that both signals are mainly due to the same electronic mechanism. © 1999 American Institute of Physics.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1063/1.1150082
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  • 5
    Digitale Medien
    Digitale Medien
    A 4 g, battery-powered, data logger accelerometer for free-flying birds (1999)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 70 (1999), S. 4394-4397 
    Details
    ISSN: 1089-7623
    Quelle: AIP Digital Archive
    Thema: Physik , Elektrotechnik, Elektronik, Nachrichtentechnik
    Notizen: This computer-controlled instrument has a battery life in excess of 16 h and fits on a circuit board that is 11.9 mm wide and 27.8 mm long. A programmable microcontroller digitizes the output of a single-axis accelerometer and stores up to 4096 acceleration values in memory. A personal computer can connect to the instrument and retrieve the data through a parallel port. The instrument can be calibrated on a small centrifuge, and the data have a linear relation to acceleration between 1 and 22 g (expandable to 50 g) with a resolution of 0.3 g. © 1999 American Institute of Physics.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1063/1.1150084
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  • 6
    Digitale Medien
    Digitale Medien
    A passive two-band sensor of sunlight-excited plant fluorescence (1999)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 70 (1999), S. 4386-4393 
    Details
    ISSN: 1089-7623
    Quelle: AIP Digital Archive
    Thema: Physik , Elektrotechnik, Elektronik, Nachrichtentechnik
    Notizen: We have designed and built a passive remote sensor of sunlight-excited chlorophyll fluorescence (U.S. Patent No. 5,567,947, Oct. 22, 1996) which provides for the real-time, in situ sensing of photosynthetic activity in plants. This sensor, which operates as a Fraunhofer line discriminator, detects light at the cores of the lines comprising the atmospheric oxygen A and B bands, centered at 762 and 688 nm, respectively. These bands also correspond to wavelengths in the far-red and red chlorophyll fluorescence bands. The sensor is based on an induced fluorescence approach; as light collected from fluorescing plants is passed through a low-pressure cell containing oxygen, the oxygen absorbs the energy and subsequently reemits photons which are then detected by a photomultiplier tube. Since the oxygen in the cell absorbs light at the same wavelengths that have been strongly absorbed by the oxygen in the atmosphere, the response to incident sunlight is minimal. This mode of measurement is limited to target plants sufficiently close in range that the plants' fluorescence is not itself appreciably absorbed by atmospheric oxygen (∼200 m). In vivo measurements of fluorescence in the 760 and 690 nm bands of vegetation in full sunlight are also presented. Measurements of plant fluorescence at the single-plant canopy level were obtained from greenhouse-grown bean plants subjected to a range of nitrogen treatments. The ratio of the fluorescence obtained from the two measurement bands showed statistically significant variation with respect to nitrogen treatments. © 1999 American Institute of Physics.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1063/1.1150083
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  • 7
    Digitale Medien
    Digitale Medien
    An instrument for performing laser capture microdissection of single cells (1999)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 70 (1999), S. 4377-4385 
    Details
    ISSN: 1089-7623
    Quelle: AIP Digital Archive
    Thema: Physik , Elektrotechnik, Elektronik, Nachrichtentechnik
    Notizen: We have developed a new form of laser capture microdissection (LCM) optimized for isolating and concentrating single cells from a tissue slide for subsequent molecular analysis. In LCM an infrared laser diode is used together with a microscope to locally melt a thin film of ethylene vinyl acetate (EVA) placed in contact or close proximity to microscopically targeted cells. Since the desired cells adhere to the film where it has been melted, they are extracted from their adjacent tissue in the specimen when the film is separated from the slide. In our system the EVA is bonded to a cylindrical substrate resulting in a very small area of contact between the EVA and the slide which minimizes contamination to levels consistent with analyzing a few cells of a selected cell type. By collecting cells at different portions about the cylinder periphery, the novel geometry also allows the concentration of cells from different slides onto a single substrate, enabling very sensitive molecular analysis to be performed on collections of rare cells. A computer controlled mechanism gently lowers the cylinder to either contact the slide with a small preload force, or provide a minute gap between the cylinder and the tissue. In the latter noncontact mode, the possibility of stray contamination is further reduced since EVA/tissue contact is only made at the location of the laser beam at a minute spot. The mechanism also can rotate the cylinder to provide fresh EVA capture surface after it has raised the cylinder off the slide. A method of fabricating the required precision cylinders of EVA capture surface is described which uses a precision mold cavity and a reusable substrate made of polycarbonate and stainless steel. Results are presented for the preload and noncontact modes which demonstrate the capabilities of the system to capture and concentrate targeted single cells from a complex tissue.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1063/1.1150043
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  • 8
    Digitale Medien
    Digitale Medien
    ac ohm meter for low-temperature thermometry (1999)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 70 (1999), S. 2365-2371 
    Details
    ISSN: 1089-7623
    Quelle: AIP Digital Archive
    Thema: Physik , Elektrotechnik, Elektronik, Nachrichtentechnik
    Notizen: A high accuracy, low excitation ohm meter optimized for cryogenic thermometry is described. While the instrument simply measures the ac voltage induced across a resistance thermometer for a fixed applied current, a number of design innovations were necessary in order to maintain a high signal-to-noise ratio and absolute accuracy of greater than 10−4 with excitation voltages as low as 50 μV. Among these are a very high stability ac oscillator, a precision current source both stable and accurate with large capacitance loads, and an amplitude locked feedback loop to permit effective filtering of low level 60 Hz pickup. © 1999 American Institute of Physics.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1063/1.1149764
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  • 9
    Digitale Medien
    Digitale Medien
    Experimental studies on a compact electron cyclotron resonance plasma x-ray source (1999)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 70 (1999), S. 2637-2645 
    Details
    ISSN: 1089-7623
    Quelle: AIP Digital Archive
    Thema: Physik , Elektrotechnik, Elektronik, Nachrichtentechnik
    Notizen: A compact electron cyclotron resonance plasma x-ray source, which has a potential use for medical imaging is presented in this article. In this article, the experimental system and the characterization studies on plasma and x ray are presented. Using a Langmuir probe, the plasma parameters are measured for different magnetic field profiles and gas pressures. The x-ray spectrum is obtained for various gas pressures and magnetic field profiles. In the x-ray spectrum, the Bremstrahlung radiation, peaking at 20–60 keV is observed and the final energy of the x ray is extended up to ∼200 keV. Thermo luminescence dosimeter (CaSO4 sample) is used for estimating the dose at the port and these results are presented for typical x-ray spectra. Using a teletector, the dose at the port for various coil current is measured and these are compared with the estimated dose obtained from the x-ray spectrum. © 1999 American Institute of Physics.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1063/1.1149821
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  • 10
    Digitale Medien
    Digitale Medien
    Liquid stub tuner for ion cyclotron heating (1999)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 70 (1999), S. 2665-2673 
    Details
    ISSN: 1089-7623
    Quelle: AIP Digital Archive
    Thema: Physik , Elektrotechnik, Elektronik, Nachrichtentechnik
    Notizen: Ion cyclotron range of frequency (ICRF) heating on the large helical device (LHD) is characterized by high power (up to 12 MW) and steady state operation (30 min). The LHD is a helical device (with a major radius of 3.9 m and a minor radius of 0.6 m) with superconducting coil windings (l=2, m=10). The main purpose of physical research is to investigate currentless and disruption-free plasma. Research and development for steady state ICRF heating has been carried out in recent years: A high rf power transmission system consisting of stub tuners, a ceramic feedthrough, and an ion cyclotron heating loop antenna has been developed. In addition, steady state operation of a rf oscillator has been achieved at a power higher than 1 MW. A liquid stub tuner has been proposed as an innovation. The liquid stub tuner makes use of the difference between the rf wavelengths in liquid and in gas due to the different relative dielectric constants. The liquid stub tuner has been experimentally proved to be a reliable rf component for high power transmission systems. Test results have quantitatively demonstrated that it can be used at high rf voltage: 61 kV for 10 s and 50 kV for 30 min. Furthermore, the liquid surface can be shifted under high rf voltage without breakdown, which suggests that it can be employed as a feedback control impedance matching tool to keep reflected rf power at a low level with regard to a temporal variation of plasma loading resistance. © 1999 American Institute of Physics.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1063/1.1149826
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  • 11
    Digitale Medien
    Digitale Medien
    Spatially resolved spectra of resonantly pumped laser produced plasmas of lithium (1999)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 70 (1999), S. 2674-2680 
    Details
    ISSN: 1089-7623
    Quelle: AIP Digital Archive
    Thema: Physik , Elektrotechnik, Elektronik, Nachrichtentechnik
    Notizen: Spatially resolved visible spectra emitted from a plasma formed by focusing the output of a flashlamp pumped dye laser onto solid targets of lithium have been recorded. The effects of laser wavelength on plasma formation have been analyzed by tuning the laser to the first resonance transition in lithium at 6708 Å and comparing the results with those obtained at an off resonance wavelength of 6728 Å. Laser energies varied from 430 to 645 mJ and were focused to a spot diameter of 300 μm with a pulse length of 850 ns. Light from the plasma was focused onto the slit of a Hilger spectrograph, which incorporated a Pellin–Broca prism whose output was focused onto a charge-coupled device camera. Electron densities of 1016–1018 cm−3 were deduced from Stark width and shift measurements of the Li II 2s–2p line at 5485 Å and from the Li I 2p–4d line at 4603 Å. In this way the electron density could be mapped as a function of distance from the target. By observing emission at 5485 Å the electron density was observed to increase when the laser was tuned on resonance compared to off. This was not the case when the neutral Li I 2p–4d line was used as a diagnostic. The anomaly is accounted for by referring to both the ionization rates involved and the temporal profile of the emission. © 1999 American Institute of Physics.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1063/1.1149827
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  • 12
    Digitale Medien
    Digitale Medien
    A 400 kHz, fast-sweep Langmuir probe for measuring plasma fluctuations (1999)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 70 (1999), S. 2681-2688 
    Details
    ISSN: 1089-7623
    Quelle: AIP Digital Archive
    Thema: Physik , Elektrotechnik, Elektronik, Nachrichtentechnik
    Notizen: A novel, fast-sweep Langmuir probe has been constructed and successfully operated on "Thorello." It is based on a novel, dual channel circuit that compensates for stray capacitance and permits sweep speeds up to 400 kHz. The circuit response has been tested by measuring the known current–voltage characteristics of resistors and diodes. In addition, the probe has been used to measure the electron temperature and density as well as the plasma potential of plasmas generated in Thorello. A method of three-parameter curve fitting is used to analyze the time-dependent data. The measurements compare favorably with those derived from other standard probe techniques. © 1999 American Institute of Physics.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1063/1.1149828
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  • 13
    Digitale Medien
    Digitale Medien
    Constant current: A method for obtaining hysteresis loops in ferroelectric materials (1999)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 70 (1999), S. 2699-2702 
    Details
    ISSN: 1089-7623
    Quelle: AIP Digital Archive
    Thema: Physik , Elektrotechnik, Elektronik, Nachrichtentechnik
    Notizen: A new method is proposed to obtain hysteresis loops in ferroelectric materials in which the sample is submitted to a constant electric current. This technique was applied on poly(vinylidene fluoride), PVDF, biaxially stretched samples and the hysteresis loops of the electric displacement and electric polarization versus the electric field compared well with those obtained with the Sawyer–Tower method. The constant current method is advantageous in that no measuring amplifiers are needed and it is insensitive to prebreakdown noise. © 1999 American Institute of Physics.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1063/1.1149830
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  • 14
    Digitale Medien
    Digitale Medien
    Application of band-stop filters for the 30–200 GHz range in oversized microwave systems (1999)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 70 (1999), S. 2861-2863 
    Details
    ISSN: 1089-7623
    Quelle: AIP Digital Archive
    Thema: Physik , Elektrotechnik, Elektronik, Nachrichtentechnik
    Notizen: A simple and cheap method has been developed to prepare band-stop filters for the frequency region 30–200 GHz with a typical attenuation in the stop band of more than 27 dB. This filter consists of periodic metallic structures deposited on a thin substrate. The preparation is achieved by applying a commonly used chemical etching technique on a commercially available thin print board. These so called "capacitive meshes" are applied successfully at the Rijnhuizen Tokamak Project for protection of a microwave diagnostic against high power microwave input. © 1999 American Institute of Physics.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1063/1.1149808
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  • 15
    Digitale Medien
    Digitale Medien
    An active telescope secondary mirror control system (1999)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 70 (1999), S. 2856-2860 
    Details
    ISSN: 1089-7623
    Quelle: AIP Digital Archive
    Thema: Physik , Elektrotechnik, Elektronik, Nachrichtentechnik
    Notizen: One of the main constraints for a modern astronomical telescope is the active control of the secondary mirror, mainly for the correction of the decentering coma and defocus induced by thermomechanical distortions. The mirror movements should be smooth, as precise as the optical design requires, and restricted to within predefined limits. It should be possible to perform mirror alignment and focus corrections without pausing the exposure (online control). The Galileo telescope achieves all this by using a support structure driven via six actuator bars (a hexapod system or Stewart platform) and a real-time control system based on a transputer network that allows parallel control of each actuator. Both the hexapod secondary support and the control system have been built and tested at the telescope. The results show that the errors introduced during mirror positioning lead to optical aberrations well below the diffraction figure of the telescope, and the systems work smoothly enough to allow online control. © 1999 American Institute of Physics.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1063/1.1149807
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  • 16
    Digitale Medien
    Digitale Medien
    Electrically controlled broadband microwave attenuator with p-i-n diode switches (1999)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 70 (1999), S. 2864-2865 
    Details
    ISSN: 1089-7623
    Quelle: AIP Digital Archive
    Thema: Physik , Elektrotechnik, Elektronik, Nachrichtentechnik
    Notizen: An electrically controlled broadband attenuator composed of two p-i-n diode switches and two quadrature hybrid couplers has been newly developed. Its attenuation can be precisely controlled by electrical pulses and also easily measured by counting its pulse repetitions. It can thus be used for broadband microwave measurements, especially noise measurement. When controlled with pulses whose width was 10 μs and repetition frequencies were between 10 and 90 kHz, this attenuator's attenuation to repetition frequencies was linear for signal frequencies in the range of 2–12 GHz. © 1999 American Institute of Physics.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1063/1.1149809
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  • 17
    Digitale Medien
    Digitale Medien
    Design and evaluation of a low thermal electromotive force guarded scanner for resistance measurements (1999)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 70 (1999), S. 2866-2871 
    Details
    ISSN: 1089-7623
    Quelle: AIP Digital Archive
    Thema: Physik , Elektrotechnik, Elektronik, Nachrichtentechnik
    Notizen: The design and testing of a low thermal electromotive force guarded scanner, developed to provide completely guarded switching when used with actively guarded resistance bridge networks, is described. The design provides a continuous guard circuit trace on the scanner circuit boards that surrounds the relay contacts and protects the measurement circuit from leakages to ground. Modification to the circuit boards and relays of the guarded scanner are explained. Several tests were developed to evaluate the guarding effectiveness, including isolating sections of the guard circuit to create a potential drop between the main and guard circuits. Calibration of standard resistors using the guarded scanner has shown relative differences less than 1×10−6, 30×10−6, and 150×10−6 for measurements made with and without the guarded scanner at nominal resistances of 1, 10, and 100 GΩ, respectively. The substitution method was used to significantly reduce the relative differences between channels to less than 0.5×10−6, 3×10−6, and 30×10−6 for nominal resistances of 1, 10, and 100 GΩ, respectively. Applications for the guarded scanner in automated direct current measurement systems are presented. © 1999 American Institute of Physics.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1063/1.1149810
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  • 18
    Digitale Medien
    Digitale Medien
    Low-noise differentiator preamplifier for photogenerated signals (1999)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 70 (1999), S. 2169-2170 
    Details
    ISSN: 1089-7623
    Quelle: AIP Digital Archive
    Thema: Physik , Elektrotechnik, Elektronik, Nachrichtentechnik
    Notizen: A low-noise preamplifier to perform a derivative of photogenerated signals is proposed. The novel structure is based on an inductive feedback preamplifier which performs preamplification and a derivative of the photogenerated current in a single stage. A breadboard circuit implementation and noise measurements are presented. Comparative noise measurements show that the proposed architecture is competitive with the classical differentiator preamplifier © 1999 American Institute of Physics.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1063/1.1149730
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  • 19
    Digitale Medien
    Digitale Medien
    A novel analog current-conveyor multiplier circuit (1999)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 70 (1999), S. 2171-2172 
    Details
    ISSN: 1089-7623
    Quelle: AIP Digital Archive
    Thema: Physik , Elektrotechnik, Elektronik, Nachrichtentechnik
    Notizen: A four-quadrant analog current multiplier circuit is proposed by using Gilbert's current Cell (Ref. 〈citeref RID="R1" STYLE="ONLINE"〉1) and the modified current conveyor (Ref. 〈citeref RID="R2" STYLE="ONLINE"〉2). © 1999 American Institute of Physics.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1063/1.1149736
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  • 20
    Digitale Medien
    Digitale Medien
    Contactless angle measurement (1999)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 70 (1999), S. 2175-2176 
    Details
    ISSN: 1089-7623
    Quelle: AIP Digital Archive
    Thema: Physik , Elektrotechnik, Elektronik, Nachrichtentechnik
    Notizen: The apparatus described uses polarized light to trace the rotation angle of an object. The result of the measurement does not depend on the distance between the object and the base surface within a wide range, and the resolution is better than 0.25° with the full range of 180°. There are no electrical contacts to the rotating object. © 1999 American Institute of Physics.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1063/1.1149731
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  • 21
    Digitale Medien
    Digitale Medien
    Nonswitching van der Pauw technique using two different modulating frequencies (1999)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 70 (1999), S. 2177-2178 
    Details
    ISSN: 1089-7623
    Quelle: AIP Digital Archive
    Thema: Physik , Elektrotechnik, Elektronik, Nachrichtentechnik
    Notizen: We present a nonswitching van der Pauw technique using two independent ac current sources and two lock-in amplifiers. This technique may be useful to measure the resistance of delicate samples that might be easily damaged by electric shocks induced from switching, and can be extended to measure the anisotropy of resistance. © 1999 American Institute of Physics.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1063/1.1149738
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  • 22
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    Digitale Medien
    Apparatus for direct addition of reagents into a nuclear magnetic resonance (NMR) sample in the NMR probe (1999)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 70 (1999), S. 2173-2174 
    Details
    ISSN: 1089-7623
    Quelle: AIP Digital Archive
    Thema: Physik , Elektrotechnik, Elektronik, Nachrichtentechnik
    Notizen: Nuclear magnetic resonance (NMR) is a widely used tool in chemistry and biochemistry. It is occasionally necessary to add small aliquots of solvents or reagents repeatedly into the NMR tube. Ordinarily this is accomplished only by ejecting the sample and carrying out the addition outside the probe. It would be preferable to add the aliquot directly into the sample. We have designed and implemented a delivery system to accomplish this. This apparatus is particularly applicable to a recent NMR titration method for measuring relative pK's and to experiments where temperature must also be varied. This apparatus provides a safe, simple, and inexpensive method for repeated aliquot addition directly into the sample in the NMR probe. © 1999 American Institute of Physics.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1063/1.1149737
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  • 23
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    Digitale Medien
    Erratum: "The beam emission spectroscopy diagnostic on the DIII-D tokamak" [Rev. Sci. Instrum. 70, 913 (1999)] (1999)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 70 (1999), S. 2179-2179 
    Details
    ISSN: 1089-7623
    Quelle: AIP Digital Archive
    Thema: Physik , Elektrotechnik, Elektronik, Nachrichtentechnik
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1063/1.1149732
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  • 24
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    Digitale Medien
    A new instrument for measuring both the magnitude and angle of low level linear birefringence (1999)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 70 (1999), S. 3847-3854 
    Details
    ISSN: 1089-7623
    Quelle: AIP Digital Archive
    Thema: Physik , Elektrotechnik, Elektronik, Nachrichtentechnik
    Notizen: This article describes a sensitive method for measuring both the magnitude and the angle of the fast axis of low level linear birefringence in optical materials. Several different approaches have been investigated and one of them has been chosen as the basis for a linear birefringence measurement instrument. The instrument employs a low birefringence photoelastic modulator for modulating the polarization states of a He–Ne laser beam. After the modulated laser beam passes through the sample, two detecting channels analyze the polarization change caused by the sample. An algorithm has been developed to calculate the magnitude and angle of the retardance in a sample. A computer program implements the algorithm and displays the calculated values. Using this instrument, selected samples with different levels of linear birefringence have been studied. The resulting instrument achieves high precision and sensitivity for the final measurements. The sensitivity of the magnitude of linear birefringence is better than 0.005 nm (∼0.003 ° with a He–Ne laser at 632.8 nm), and the sensitivity of the fast axis angle of the sample is 〈1 ° (for retardance ≥0.5 nm). © 1999 American Institute of Physics.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1063/1.1150000
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  • 25
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    Digitale Medien
    Performance of the grating-crystal monochromator of the ALOISA beamline at the Elettra Synchrotron (1999)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 70 (1999), S. 3855-3864 
    Details
    ISSN: 1089-7623
    Quelle: AIP Digital Archive
    Thema: Physik , Elektrotechnik, Elektronik, Nachrichtentechnik
    Notizen: The new beamline ALOISA, now operational at the Elettra Synchrotron, is designed for surface studies by means of several experimental techniques: surface x-ray diffraction and reflectivity, photoemission spectroscopy, photoelectron diffraction, e−-Auger coincidence spectroscopy. A new monochromator has been specifically designed and realized for this multipurpose beamline: it makes use of a channel-cut Si crystal dispersive element for the 3–8 keV range and of a plane mirror-plane grating element for the 200–2000 eV range. Both dispersive elements share the same optical system. In the low energy range (200–900 eV) the spectral resolving power exceeds 5000 while maintaining a throughput higher than 1010 photons/s/200 mA/0.02% BW. In the case of the N2 1s→π* and Ne 1s→3p transitions, the extremely high signal-to-noise ratio of the absorption spectra allowed a very accurate determination of the corresponding natural linewidth (116±2 and 250±10 eV, respectively). Moreover, the vibrational structure of the CO–oxygen 1s→π* transition has been fully resolved. In the high energy range, the measured flux exceeds 1010 photons/s/200 mA up to 6.5 keV with a resolving power of ∼7500. © 1999 American Institute of Physics.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1063/1.1150001
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  • 26
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    Digitale Medien
    Design and performance of the JAERI superconducting linac for high-power free-electron laser (1999)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 70 (1999), S. 3865-3868 
    Details
    ISSN: 1089-7623
    Quelle: AIP Digital Archive
    Thema: Physik , Elektrotechnik, Elektronik, Nachrichtentechnik
    Notizen: A superconducting rf linac has been required to realize high-duty operation and low-electricity consumption for a high-average-power and high-efficiency free-electron laser (FEL). The JAERI FEL superconducting linac consists of a 250 kV electron gun, a subharmonic normal-conducting buncher (SHB) of 83.3 MHz, and two single-cell and two five-cell superconducting cavities of 499.8 MHz. The gun was typically operated around 200 kV to reduce space-charge effects. A combination of the SHB and the two single-cell cavities enabled a high-current beam of more than 10 A by utilizing a thermionic cathode and a grid pulser. The full width at half maximum bunch length and energy resolution were measured to be 22 ps and 1% or less, respectively. The measured results agreed with calculations utilizing the modified PARMELA code. This showed the validity of the linac design for the FEL. With this beam quality, high-average FEL power of 0.1 kW at a 24–28 μm wavelength was obtained in a quasi-cw mode. © 1999 American Institute of Physics.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1063/1.1150002
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  • 27
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    Digitale Medien
    Analysis of an asymmetric resonant cavity as a beam monitor (1999)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 70 (1999), S. 2300-2313 
    Details
    ISSN: 1089-7623
    Quelle: AIP Digital Archive
    Thema: Physik , Elektrotechnik, Elektronik, Nachrichtentechnik
    Notizen: We analyze the excitation of an arbitrary, externally coupled resonant structure by a charged particle beam, providing a rigorous formulation of the effect of spurious modes and intrinsic mode nonlinearity on inferred beam coordinates. Results are illustrated for a two-cavity system employed for beam-position monitoring with an idealized front-end signal processor. © 1999 American Institute of Physics.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1063/1.1149756
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  • 28
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    Digitale Medien
    Trim coil system design of a superconducting ring cyclotron (1999)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 70 (1999), S. 2293-2299 
    Details
    ISSN: 1089-7623
    Quelle: AIP Digital Archive
    Thema: Physik , Elektrotechnik, Elektronik, Nachrichtentechnik
    Notizen: The trim coil system of a superconducting ring cyclotron currently under design at RIKEN is composed of five sets of superconducting and twenty sets of normal-conducting coils. A major correction for isochronization of the magnetic field is accomplished by the superconducting coils, and a fine correction by the normal-conducting coils. For an optimal design of the system, a numerical procedure was developed to generate isochronous fields for design nuclei and consequently current settings on the main and trim coils, employing an iteration of a least-squares fitting to minimize orbital frequency errors. The main and normal-conducting coils can also be used to correct unwanted harmonic fields with sector dependent and/or radially localized excitations. The correction schemes were conceived for presumed error fields, alignment tolerances being estimated based upon beam optics requirements. On the other hand, a new trim coil design was envisaged, which comprises only superconducting trim coils. The subcoils in the present five-set design can be independently excited to replace the normal-conducting coils. This option may be more economical, but complications on the superconducting coil system raise a reliability concern. © 1999 American Institute of Physics.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1063/1.1149755
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  • 29
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    Digitale Medien
    On apparatus for studying catalysts and catalytic processes using neutron scattering (1999)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 70 (1999), S. 2325-2330 
    Details
    ISSN: 1089-7623
    Quelle: AIP Digital Archive
    Thema: Physik , Elektrotechnik, Elektronik, Nachrichtentechnik
    Notizen: The design of a cell, built to investigate catalysis and catalytic processes, is reported. The cell is for use at ISIS spallation neutron source at the Rutherford Appleton Laboratory. It is required to operate in a dual manner either under gas flows of controlled composition at low pressure (ambient −5 bar) and at high vacuum (10−6 mbar working pressure). The temperature range of this cell is 4–1273 K. It will be used on a variety of instrument beam lines on ISIS. In use the cell is attached either to a furnace or cryofurnace center-stick assembly and gas is supplied from a gas circuit assembly. © 1999 American Institute of Physics.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1063/1.1149758
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  • 30
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    Digitale Medien
    Preliminary experiment of total reflection x-ray fluorescence using two glancing x-ray beams excitation (1999)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 70 (1999), S. 1621-1623 
    Details
    ISSN: 1089-7623
    Quelle: AIP Digital Archive
    Thema: Physik , Elektrotechnik, Elektronik, Nachrichtentechnik
    Notizen: In conventional total reflection x-ray fluorescence (TXRF), one glancing x-ray beam irradiates the sample carrier for excitation of x-ray fluorescence. However, it is also possible to excite x-ray fluorescence by multiple x-ray beams. We performed a preliminary TXRF experiment excited by two independent glancing x-ray beams. The two x-ray beams excitation would be effective to enhance the intensity of x-ray fluorescence and to improve the detection limit in TXRF. X rays from both a rotating Mo anode x-ray tube and a glow discharge x-ray tube with an Fe target irradiated a Cr thin film sample on a quartz glass. The x-ray fluorescence of Cr Kα from the sample was slightly enhanced compared with the intensity measured by one x-ray beam excitation. © 1999 American Institute of Physics.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1063/1.1149687
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  • 31
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    Digitale Medien
    A dusty double plasma device (1999)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 70 (1999), S. 2345-2348 
    Details
    ISSN: 1089-7623
    Quelle: AIP Digital Archive
    Thema: Physik , Elektrotechnik, Elektronik, Nachrichtentechnik
    Notizen: A novel dusty plasma device to create spatially and temporally uniform steady state dusty plasma is described. An ultrasonic vibrator is used to vibrate a dust dispenser which disperses the dust uniformly through a fine mesh. A dusty plasma of large dimension with controllable dust density is produced. Measured dusty plasma parameters are compared with existing theories. Some experimental results related to propagation characteristics of dust-ion-acoustic waves in a dusty plasma column are presented. © 1999 American Institute of Physics.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1063/1.1149761
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  • 32
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    Digitale Medien
    A low stray light, high current, low energy electron source (1999)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 70 (1999), S. 3886-3888 
    Details
    ISSN: 1089-7623
    Quelle: AIP Digital Archive
    Thema: Physik , Elektrotechnik, Elektronik, Nachrichtentechnik
    Notizen: A design of an electron gun system is presented whose stray light emission is reduced by about three orders of magnitude compared to a regular low-energy electron diffraction gun. This is achieved by a combination of a BaO cathode run at rather low temperature and a 30° tandem parallel-plate analyzer used as an optical baffle. The system provides a high beam current of several microampers at 50 eV beam energy. The system can be used down to ∼10 eV. © 1999 American Institute of Physics.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1063/1.1150007
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  • 33
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    Digitale Medien
    An improved method for detecting hot spots in field emission cathode arrays (1999)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 70 (1999), S. 3889-3891 
    Details
    ISSN: 1089-7623
    Quelle: AIP Digital Archive
    Thema: Physik , Elektrotechnik, Elektronik, Nachrichtentechnik
    Notizen: We present an improved liquid crystal microthermography technique for the detection of defects in large area field emission cathode arrays. Defects can cause electrical leakage paths, leading to localized heating at the defect location. The thermal gradients at these hot spots can be detected by liquid crystal microthermography, but, the direct placement of the liquid crystal is a two step process. First the liquid crystal is deposited by spin coating the device and the liquid crystal has to be removed from the device after the test. This process, apart from being time consuming, can lead to contamination of the test device. In this article, we present an improved liquid crystal microthermography technique for the detection of hot spots in field emitter arrays. The improvement is obtained by hermetically sealing the liquid crystal material inside a packaged assembly made from a glass support and a thin plastic membrane. We have used the new method for the detection of hot spots in large area field emission cathode arrays. This technique provides accurate detection of hot spot locations caused by leakage currents as low as 100 μA.© 1999 American Institute of Physics.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1063/1.1150008
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  • 34
    Digitale Medien
    Digitale Medien
    Measurement of thermal diffusivity of air using photopyroelectric interferometry (1999)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 70 (1999), S. 2372-2378 
    Details
    ISSN: 1089-7623
    Quelle: AIP Digital Archive
    Thema: Physik , Elektrotechnik, Elektronik, Nachrichtentechnik
    Notizen: A new photopyroelectric (PPE) method for measuring the thermal diffusivity of ambient gases with optimal precision is introduced. The technique is based on destructive PPE interferometric detection inside a thermal-wave resonant cavity with an optically transparent wall. A new PPE sensor design generating purely thermal-wave interference is used to improve the signal-to-noise ratio and the measurement dynamic range and precision by suppressing the large optically transmitted base line signal. Cavity-length scanning is employed and the thermal diffusivity of air is measured with third-significant-figure precision. Comparisons of measurement precision are made with experimental results obtained using a transparent-wall PPE thermal-wave cavity in the single-ended (noninterferometric) mode. The physical signal generation mechanisms are also discussed. © 1999 American Institute of Physics.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1063/1.1149765
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  • 35
    Digitale Medien
    Digitale Medien
    Automated constant voltage anemometer with in situ measurements of overheat and time constant of the hot wire (1999)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 70 (1999), S. 2384-2386 
    Details
    ISSN: 1089-7623
    Quelle: AIP Digital Archive
    Thema: Physik , Elektrotechnik, Elektronik, Nachrichtentechnik
    Notizen: The operational features of an automated constant voltage anemometer (ACVA) designed for flight applications have been presented. Diagnostic voltage outputs are provided in ACVA, which will enable the calculation of in situ hot wire time constant and overheat for postprocessing of the turbulence data from the measured output voltage. TTL outputs provide identification of the output state. Using this automated system in a wind tunnel, time constant values obtained as a function of the hot wire Reynolds numbers and hot wire currents (overheats) are presented for 5 and 10 μm hot wires showing agreement with prior analysis and results © 1999 American Institute of Physics.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1063/1.1149790
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  • 36
    Digitale Medien
    Digitale Medien
    Soft, entirely photoplastic probes for scanning force microscopy (1999)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 70 (1999), S. 2398-2401 
    Details
    ISSN: 1089-7623
    Quelle: AIP Digital Archive
    Thema: Physik , Elektrotechnik, Elektronik, Nachrichtentechnik
    Notizen: A new probe made entirely of plastic material has been developed for scanning probe microscopy. Using a polymer for the cantilever facilitates the realization of mechanical properties that are difficult to achieve with classical silicon technology. The new cantilever and tip presented here are made of an epoxy-based photoplastic. The fabrication process is a simple batch process in which the integrated tip and the lever are defined in one photolithography step. The simplicity of the fabrication step, the use of a polymer as material, and the ability to reuse the silicon mold lead to a soft low-cost probe for scanning force microscopy. Imaging soft condensed matter with photoplastic levers, which uses laser beam deflection sensing, exhibits a resolution that compares well with that of commercially available silicon cantilevers. © 1999 American Institute of Physics.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1063/1.1149767
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  • 37
    Digitale Medien
    Digitale Medien
    System analysis of the force-feedback method for force curve measurements (1999)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 70 (1999), S. 2402-2407 
    Details
    ISSN: 1089-7623
    Quelle: AIP Digital Archive
    Thema: Physik , Elektrotechnik, Elektronik, Nachrichtentechnik
    Notizen: The force-feedback method is a promising technique to measure accurate force curves in atomic force spectroscopy. In this article, we describe criteria of the stability for the force-feedback system containing a proportional amplifier with first-order lag. We derive the criteria from an equation of the cantilever movement with higher-order vibration modes under force interaction. The criteria predict that a proportional amplifier with a certain gain and a "very high" cutoff frequency is required to stabilize the feedback system when the critical force gradient exceeds the cantilever stiffness. To measure a force curve, including the steep part (−17 N/m) with a soft (0.2 N/m) and poor-damping (2×10−7 kg/s) cantilever, the amplifier for the force-feedback controller must have a frequency response wider than 16 MHz and gain larger than 16.8. Moreover, the feedback controller with only an integrator, which is popular in scanning tunneling microscopy and atomic force microscopy, does not contribute to reducing the discontinuity of the force curve. © 1999 American Institute of Physics.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1063/1.1149768
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  • 38
    Digitale Medien
    Digitale Medien
    Mass spectrometric estimation of gas permeation coefficients for thin polymer membranes (1999)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 70 (1999), S. 2414-2420 
    Details
    ISSN: 1089-7623
    Quelle: AIP Digital Archive
    Thema: Physik , Elektrotechnik, Elektronik, Nachrichtentechnik
    Notizen: We have developed a new method to estimate the permeation coefficient of gases through polymer membranes. A fixed volume of gas is put in a gas cell and introduced into ultrahigh vacuum. After positioning the gas cell to face a quadrupole mass spectrometer, the partial pressure of the gases are measured as function of time. In a simple model, the partial pressure as function of time obeys an exponential law. A formula is derived to calculate the permeation coefficient with the time constant of the partial pressure decay and geometric parameters of the gas cell as input. Using these parameters the method gives absolute permeation values without calibration. If the time constant is difficult to establish (this may happen for membranes with a low permeation coefficient), the permeation coefficient can be estimated by extrapolating the partial pressure to t=0. The method can be used to study the permeation behavior of individual components of gas mixtures. The sample size can be about two orders of magnitude smaller than usually used in conventional permeation measurements. The method is illustrated with oriented polypropylene and polyethylene terephtalate membranes of different thickness. The estimated permeation coefficients are in reasonable agreement with values obtained from a control experiment using a gas chromatograph and with values from the literature. © 1999 American Institute of Physics.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1063/1.1149770
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  • 39
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    Digitale Medien
    A solution flow system for hydrothermal–electrochemical growth of multilayered thin films (1999)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 70 (1999), S. 2432-2437 
    Details
    ISSN: 1089-7623
    Quelle: AIP Digital Archive
    Thema: Physik , Elektrotechnik, Elektronik, Nachrichtentechnik
    Notizen: A solution flow system equipment for hydrothermal–electrochemical synthesis of advanced thin films has been designed, constructed, and successfully tested. The synthesis using recyclable (aqueous) solutions as precursors can be carried out up to temperature of 200 °C and pressure of 50 kg cm−2 utilizing electrochemical activation of the nucleation and growth processes. Any clear solution can be used as a precursor; there are almost no limitations of the substrates used. The equipment is easy to use, versatile, and inexpensive. Applicability of the solution flow system for synthesis of advanced materials has been demonstrated using single-layer and multilayer BaTiO3–SrTiO3 thin films. Our equipment allows control of the microstructure of the films in a nanometric scale by changing the preparation conditions, for example the growth rate can be increased by increasing the flow rate. In addition, the multilayered films can be prepared in only one experiment just by changing the kind of flowing solution. The technique using the solution flow under the hydrothermal–electrochemical conditions is an important step in integration of the solution processing with the advanced device technology. © 1999 American Institute of Physics.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1063/1.1149772
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  • 40
    Digitale Medien
    Digitale Medien
    Development of magnetization measurement under high pressure and pulsed high magnetic field (1999)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 70 (1999), S. 2445-2447 
    Details
    ISSN: 1089-7623
    Quelle: AIP Digital Archive
    Thema: Physik , Elektrotechnik, Elektronik, Nachrichtentechnik
    Notizen: A method for measuring magnetization under high pressure and pulsed high magnetic field was developed for a Drickamer-type cell using diamond anvils and an insulator gasket. As the first test, the magnetization of invar alloy Fe0.65Ni0.35 was measured at room temperature up to 8 GPa in a pulsed field of 10 T with a width of 4 ms. The magnetization decreased with increasing pressure, indicating a transition to a paramagnetic state at 5–6 GPa, in accordance with the results of previous experiments using conventional methods such as ac susceptibility measurement. © 1999 American Institute of Physics.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1063/1.1149774
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  • 41
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    Digitale Medien
    Axisymmetric drop shape analysis as penetration Langmuir balance (1999)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 70 (1999), S. 2438-2444 
    Details
    ISSN: 1089-7623
    Quelle: AIP Digital Archive
    Thema: Physik , Elektrotechnik, Elektronik, Nachrichtentechnik
    Notizen: A new Langmuir-type pendant-drop penetration film balance has been developed combining a Langmuir-type pendant-drop film balance with a new rapid-subphase-exchange technique. In addition to the determination of surface pressure—molecular area isotherms of insoluble monolayers deposited on the surface of a pendant drop, it allows the study of reactions with some surfactant added to the subphase. The monolayer is spread on the surface of a drop suspended from a capillary, which is the outer one of an arrangement of two coaxial capillaries connected to the different branches of a microinjector. Once the film is brought to the desired state of compression by varying the drop volume with the microinjector, the subphase liquid in the drop can be exchanged quantitatively by means of the coaxial capillaries. This exchange is complete for a through-flow of at least three times the drop volume, and the monolayers endure it at all tested film pressures. The determination of surface tension as a function of surface area is performed using axisymmetric drop shape analysis (ADSA). The complete set-up, i.e., the image capturing and microinjector system is fully computer controlled by a user-friendly and fully Windows integrated program, including the ADSA surface tension calculus algorithm. As a penetration film balance, pendant-drop methodologies offer a wide range of advantages such as a more stringent control of the environmental conditions and therefore, more uniform temperature, pressure and concentration along the interface, small amounts of material needed, and a 20 times greater interface/volume ratio than in conventional Langmuir toughs. © 1999 American Institute of Physics.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1063/1.1149773
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  • 42
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    Digitale Medien
    Characterization of electrochemically etched tungsten tips for scanning tunneling microscopy (1999)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 70 (1999), S. 3970-3972 
    Details
    ISSN: 1089-7623
    Quelle: AIP Digital Archive
    Thema: Physik , Elektrotechnik, Elektronik, Nachrichtentechnik
    Notizen: Shape and composition of electrochemically etched tungsten tips for use in scanning tunneling microscopy (STM) were investigated in a transmission electron microscope (TEM) with a Gathan imaging filter (GIP). The tips are prepared by a lamella drop-off technique. We observe typical tip radii of less than 10 nm. After a storage of some days under ambient conditions, an amorphous oxide film is detectable. The electron energy-loss spectroscopy confirms that the surface is contaminated by compounds that contain carbon, too. © 1999 American Institute of Physics.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1063/1.1150022
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  • 43
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    Digitale Medien
    High-pressure autoclave for multipurpose nuclear magnetic resonance measurements up to 10 MPa (1999)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 70 (1999), S. 2448-2453 
    Details
    ISSN: 1089-7623
    Quelle: AIP Digital Archive
    Thema: Physik , Elektrotechnik, Elektronik, Nachrichtentechnik
    Notizen: High-pressure nuclear magnetic resonance (NMR) is an established method in NMR spectroscopy: on-line coupling of high-performance liquid chromatography with NMR, for example, reveals structural information which cannot be obtained with any other method. However, applications has been focused solely on high-pressure NMR spectroscopy, even though high-pressure NMR imaging allows in situ studies of processes such as the fluid exchange in porous media. A versatile high-pressure autoclave for NMR imaging is described in this article. The autoclave allows measurements in any horizontal NMR imager using magnetic field coil systems with an inside diameter of more than 70 mm. Any sample with a diameter up to 28 mm and a length of about 200 mm can be investigated. The autoclave is constructed for operating pressures up to 10 MPa and is temperature controlled between 10 and 60 °C. The materials of the high-pressure cell which are the thermoplastic polyetheretherketon (PEEK) for the pressure tube and brass (63% Cu, 37% Zn) for the caps also permit investigations with aggressive fluids such as supercritical carbon dioxide. Inlet and outlet valves allow replacement of fluids and pressure variations in the autoclave during the NMR measurement. FLASH NMR images of the fluid exchange of methanol for liquid carbon dioxide in silica alcogels at 6.5 MPa are presented in order to demonstrate possible applications. © 1999 American Institute of Physics.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1063/1.1149775
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  • 44
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    Digitale Medien
    More vertical etch profile using a Faraday cage in plasma etching (1999)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 70 (1999), S. 2458-2461 
    Details
    ISSN: 1089-7623
    Quelle: AIP Digital Archive
    Thema: Physik , Elektrotechnik, Elektronik, Nachrichtentechnik
    Notizen: Scanning electron microscope images of sidewalls obtained by plasma etching of an SiO2 film with and without a Faraday cage have been compared. When the substrate film is etched in the Faraday cage, faceting is effectively suppressed and the etch profile becomes more vertical regardless of the process conditions. This is because the electric potential in the cage is nearly uniform and therefore distortion of the electric field at the convex corner of a microfeature is prevented. The most vertical etch profile is obtained when the cage is used in fluorocarbon plasmas, where faceting is further suppressed due to the decrease in the chemical sputtering yield and the increase in the radical/ion flux on the substrate. © 1999 American Institute of Physics.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1063/1.1149777
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  • 45
    Digitale Medien
    Digitale Medien
    A simple strain cell for the measurement of the gauge factor of a thin film (1999)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 70 (1999), S. 2074-2075 
    Details
    ISSN: 1089-7623
    Quelle: AIP Digital Archive
    Thema: Physik , Elektrotechnik, Elektronik, Nachrichtentechnik
    Notizen: In this article, we present the design and fabrication of a simple strain cell using a displacement dial gauge. The strain sensitivity for this cell is of the order of 10−5 which is approximately equal to that obtained by cantilever bending. The advantage of this cell is that it can be used for the determination of the strain for the metal films deposited on any type of substrates, which do not have well defined Young's modulus. The gauge factor for discontinuous silver film deposited on softened poly-2-vinylpyridine substrate protected by an oxide overlayer coating is determined using this strain cell and the value of the gauge factor for this film is about 45. © 1999 American Institute of Physics.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1063/1.1149715
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  • 46
    Digitale Medien
    Digitale Medien
    Electronic simulation of a multiterminal quantum Hall effect device (1999)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 70 (1999), S. 2082-2086 
    Details
    ISSN: 1089-7623
    Quelle: AIP Digital Archive
    Thema: Physik , Elektrotechnik, Elektronik, Nachrichtentechnik
    Notizen: A circuit with only resistors and unity gain amplifiers can be proven to be equivalent to the Ricketts and Kemeny electrical model of multiterminal quantum Hall effect (QHE) devices. By means of the new equivalent circuit, commercial software for electronic circuit analysis can be used to study a QHE measurement system. Moreover, it can be easily implemented, and we were able to build a circuit that simulates the electrical behavior of a QHE device. Particular care was taken in the design to reduce the effect of parasitic capacitances, which act as loads connected to the device terminals. Bootstrap buffers have been adopted to significantly reduce the capacitance of input stage. The small residual loading effect can be calculated and eliminated, allowing simulation of a QHE device with good accuracy. © 1999 American Institute of Physics.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1063/1.1149717
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  • 47
    Digitale Medien
    Digitale Medien
    An improved surface plasmon resonance imaging apparatus (1999)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 70 (1999), S. 2076-2081 
    Details
    ISSN: 1089-7623
    Quelle: AIP Digital Archive
    Thema: Physik , Elektrotechnik, Elektronik, Nachrichtentechnik
    Notizen: The design, construction, and initial use of an improved surface plasmon resonance imaging instrument are described. The instrument construction allows for introduction of large samples (50×50 mm) and is arranged with a unique horizontal sample geometry. This horizontal geometry provides for the eventual introduction of standard robotics both for substrate handling and liquid delivery, as with other commercialized analytical imaging techniques. The versatile optical train makes the instrument ideal for a wide range of sample sizes and provides for variable lateral resolution. Very small variations in colloidal Au coverage are detected on a patterned substrate, thereby demonstrating the utility of colloidal Au as a surface plasmon resonance imaging contrast reagent. © 1999 American Institute of Physics.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1063/1.1149716
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  • 48
    Digitale Medien
    Digitale Medien
    A low cost modulation technique for magneto-optical measurements (1999)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 70 (1999), S. 2095-2096 
    Details
    ISSN: 1089-7623
    Quelle: AIP Digital Archive
    Thema: Physik , Elektrotechnik, Elektronik, Nachrichtentechnik
    Notizen: A modulation–demodulation apparatus for magneto-optical Kerr effect measurements is presented. This system is based on an intensity modulated laser and on a specially designed demodulation circuit. This approach allows us to exploit the advantages offered by modulation at a much lower cost compared to the standard design based on expensive photoelastic modulators and general purpose lock-in amplifiers. © 1999 American Institute of Physics.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1063/1.1149719
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  • 49
    Digitale Medien
    Digitale Medien
    Atmospheric pressure ion focusing in a high-field asymmetric waveform ion mobility spectrometer (1999)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 70 (1999), S. 1370-1383 
    Details
    ISSN: 1089-7623
    Quelle: AIP Digital Archive
    Thema: Physik , Elektrotechnik, Elektronik, Nachrichtentechnik
    Notizen: The focusing of ions at atmospheric pressure and room temperature in a high-field asymmetric waveform ion mobility spectrometer (FAIMS) has been investigated. FAIMS operates with the application of a high-voltage, high-frequency asymmetric waveform across parallel plates. This establishes conditions wherein an ion migrates towards one of the plates because of a difference in the ion mobility at the low and high electric field conditions during application of the waveform. The migration can be stopped by applying a dc compensation voltage (CV) which serves to create a "balanced" condition wherein the ion experiences no net transverse motion. This method has also been called "transverse field compensation ion mobility spectrometry" and "field ion spectrometry®." If this experiment is conducted using a device with cylindrical geometry, rather than with flat plates, an ion focusing region can exist in the annular space between the two concentric cylinders. Ion trajectory modeling showed that the behavior of the ions in the cylindrical geometry FAIMS analyzer was unlike any previously described atmospheric pressure ion optics system. The ions appeared to be trapped, or focused by being caught between two opposing forces. Requirements for establishing this focus for a given ion were identified: the applied waveform must be asymmetric, the electric field must be sufficiently high that the mobility of the ion deviates from its low-field value during the high-voltage portion of the asymmetric waveform, and finally, the electric field must be nonuniform in space (e.g., cylindrical or spherical geometry). Experimental observations with a prototype FAIMS device, which was designed to measure the radial distribution of ions in the FAIMS analyzer region, have confirmed the results of ion trajectory modeling. © 1999 American Institute of Physics.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1063/1.1149599
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  • 50
    Digitale Medien
    Digitale Medien
    Microwave diagnostics in electron cyclotron resonance plasma sources (1999)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 70 (1999), S. 1384-1386 
    Details
    ISSN: 1089-7623
    Quelle: AIP Digital Archive
    Thema: Physik , Elektrotechnik, Elektronik, Nachrichtentechnik
    Notizen: The plasma source, which is of high importance in the optimization of the separation of the gadolinium isotopes by the plasma separation process, requires a precise knowledge of its physical characteristics. Thus, a diagnostic has been developed to estimate the microwave power inside the source. A microstrip antenna has been designed and developed in order to characterize the microwave field at 36 GHz frequency in the plasma source. The experimental results for different plasma regimes are presented. The measurements inside the plasma source show a maximum of microwave absorption for an argon pressure of 10−4 mbar with 93% absorption of the incident wave in the conditions of isotope separation. © 1999 American Institute of Physics.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1063/1.1149600
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  • 51
    Digitale Medien
    Digitale Medien
    Novel flow apparatus for investigating shear-enhanced crystallization and structure development in semicrystalline polymers (1999)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 70 (1999), S. 2097-2104 
    Details
    ISSN: 1089-7623
    Quelle: AIP Digital Archive
    Thema: Physik , Elektrotechnik, Elektronik, Nachrichtentechnik
    Notizen: An instrument to study the effects of shearing on the crystallization process in semicrystalline polymers is described. It can impose transient stresses similar to those encountered in polymer processing and provides in situ monitoring of microstructure development during and after cessation of flow. Box-like wall shear stress profiles (rise and fall times under 50 ms with maximum wall shear stress on the order of 0.1 MPa) can be applied for controlled durations. A unique feature of our device is that it accommodates a wide variety of real-time probes of structure such as visible and infrared polarimetry and light and x-ray scattering measurements. The design also allows us to retrieve the sample for ex situ optical and electron microscopy. Data are acquired with millisecond resolution enabling us to record the extent of shear deformation of the polymer melt during the pressure pulse. Our device works with small sample quantities (as little as 5 g; each experiment takes ∼500 mg) as opposed to the kilogram quantities required by previous instruments capable of imposing comparable deformations. This orders-of-magnitude reduction in the sample size allows us to study model polymers and new developmental resins, both of which are typically available only in gram-scale quantities. The compact design of the shear cell makes it possible to transport it to synchrotron light sources for in situ x-ray scattering studies of the evolution of the crystalline structure. Thus, our device is a valuable new tool that can be used to evaluate the crystallization characteristics of resins with experimental compositions or molecular architectures when subjected to processing-like flow conditions. We demonstrate some of the features of this device by presenting selected results on isotactic polypropylenes. © 1999 American Institute of Physics.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1063/1.1149720
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  • 52
    Digitale Medien
    Digitale Medien
    Investigation of the radio frequency magnetic field inside a hollow cylinder used for nuclear magnetic resonance imaging (1999)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 70 (1999), S. 2113-2115 
    Details
    ISSN: 1089-7623
    Quelle: AIP Digital Archive
    Thema: Physik , Elektrotechnik, Elektronik, Nachrichtentechnik
    Notizen: The homogeneity of the radio frequency (rf) axial magnetic field inside a solenoid composed of a set of current-carrying coils can be improved by imposing appropriate current densities in the various loops that constitute the structure. In the case of a hollow cylinder made from a single sheet of copper foil, the rf field so generated can also attain a similar degree of homogeneity without current compensation provided the copper foil is five to six times thicker than the skin depth and the cylinder's form factor (diameter/length) is of the order or less than 0.5. Numerical calculations based on some basic equations allow us to predict the rf field pattern of a cylinder of given dimensions. Experimental results obtained from a 32 MHz transmission line resonator show good agreement between theory and practice. The filling factor of this type of cylinder can also be evaluated from these calculations. © 1999 American Institute of Physics.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1063/1.1149722
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  • 53
    Digitale Medien
    Digitale Medien
    Pressure transducer mounts for internal blast measurements on thin metal walls (1999)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 70 (1999), S. 2122-2126 
    Details
    ISSN: 1089-7623
    Quelle: AIP Digital Archive
    Thema: Physik , Elektrotechnik, Elektronik, Nachrichtentechnik
    Notizen: Three mounts are described for installing pressure transducers on thin walls for internal blast measurements in which the walls undergo ductile rupture. Details of the mounts are presented and each mount is evaluated from several examples of pressure-time profiles obtained from thin steel walled cubes and ship compartment studies. Two designs proved effective, one having a flange and a sheath to protect the transducer, and another, a simpler and lighter design, consisting of a welded ring. © 1999 American Institute of Physics.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1063/1.1149724
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  • 54
    Digitale Medien
    Digitale Medien
    Use of a random phase plate as a KrF laser beam homogenizer for thin film deposition applications (1999)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 70 (1999), S. 2116-2121 
    Details
    ISSN: 1089-7623
    Quelle: AIP Digital Archive
    Thema: Physik , Elektrotechnik, Elektronik, Nachrichtentechnik
    Notizen: Fabrication of devices based on thin film structures deposited using the pulsed laser deposition technique relies on reproducibility and control of deposition rates over substrate areas as large as possible. Here we present an application of the random phase plate technique to smooth and homogenize the intensity distribution of a KrF laser footprint on the surface of a target which is to be ablated. It is demonstrated that intensity distributions over millimeter-sized spots on the target can be made insensitive to the typical changes that occur in the near-field intensity distribution of the ultraviolet output from a KrF laser. © 1999 American Institute of Physics.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1063/1.1149723
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  • 55
    Digitale Medien
    Digitale Medien
    Two-dimensional X pendulum vibration isolation table (1999)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 70 (1999), S. 2150-2154 
    Details
    ISSN: 1089-7623
    Quelle: AIP Digital Archive
    Thema: Physik , Elektrotechnik, Elektronik, Nachrichtentechnik
    Notizen: We have extended to two dimensions a previously developed vibration isolation table using crossed wire suspensions (X mechanisms). A load table is suspended using a combination of normal and upside-down X mechanisms so that it moves freely with a very long period in both horizontal directions but is moderately stiff in all other degrees of freedom. Periods of 5 s are easily achievable. The transfer function of the prototype reported here contains a number of elastic mode resonance peaks, but it is shown by analysis how to reduce or eliminate nearly all of these. © 1999 American Institute of Physics.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1063/1.1149728
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  • 56
    Digitale Medien
    Digitale Medien
    Limits on laser wakefield accelerators (1999)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 70 (1999), S. 1983-1985 
    Details
    ISSN: 1089-7623
    Quelle: AIP Digital Archive
    Thema: Physik , Elektrotechnik, Elektronik, Nachrichtentechnik
    Notizen: The longitudinal and radial wakefields produced by a single laser pulse in a plasma are calculated. The limits on the laser wakefield acceleration because of diffraction, optical guiding, and energy loss due to radiation are examined. In particular for a bi-Gaussian laser beam, the energy gain about 4.6 GeV/cm s is estimated. A general constraint on the plasma density is presented. All the limits are compared and a localized density channel of width 4.6×10−5 cm is proposed. © 1999 American Institute of Physics.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1063/1.1149698
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  • 57
    Digitale Medien
    Digitale Medien
    Angle-resolving electron-electron coincidence setup (1999)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 70 (1999), S. 1978-1982 
    Details
    ISSN: 1089-7623
    Quelle: AIP Digital Archive
    Thema: Physik , Elektrotechnik, Elektronik, Nachrichtentechnik
    Notizen: We introduce a novel angle-resolving electron-spectrometer system for coincidence studies of gas-phase targets using the timing structure of synchrotron radiation. The experimental setup, mainly consisting of a cylindrical mirror analyzer with a position sensitive detector and an electron time-of-flight spectrometer is particularly useful in cases where low-kinetic-energy electrons are measured in coincidence with high-kinetic-energy electrons. The experimental method and corresponding electronics are discussed. As an example, we present argon LMM Auger electron spectra taken in coincidence with KL2,3L2,3 and KL1L2,3 Auger electrons after resonant 1s→4p photoexcitation. © 1999 American Institute of Physics.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1063/1.1149697
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  • 58
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    Digitale Medien
    Fast pulsed radar reflectometry for the Textor Tokamak : Proceedings of the 12th topical conference on high temperature plasma diagnostics (1999)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 70 (1999), S. 1034-1037 
    Details
    ISSN: 1089-7623
    Quelle: AIP Digital Archive
    Thema: Physik , Elektrotechnik, Elektronik, Nachrichtentechnik
    Notizen: Progress in fusion research shows an increasing demand for diagnostics with high temporal and spatial resolution in order to study small and fast phenomena in fusion plasmas. Therefore, a new ten-channel pulsed radar reflectometer is under development for the TEXTOR Tokamak, to measure electron density profiles in the range of 0.4–4×1019 m−3 at a high repetition rate of 2 MHz. An additional feature of this diagnostic is the possibility to perform correlation measurements at 10 MHz repetition rate to investigate density fluctuations. The reflectometer will scan the plasma with 1-ns-long radar pulses in the 18–57 GHz range. In spite of the long flight time of the pulses of about 100 ns, the above mentioned high repetition rates could be achieved by time multiplexing the generation and reception of the radar pulses. Temporal selection of the received pulses is performed by fast switching of the local oscillators inputs of the heterodyne receiver, to generate time windows in which the reception of the reflected pulses is expected. An embedded VME controller will manage the system and store the data with a speed of 20 Msamples/s, up to a maximum of 64 Mbyte data per plasma shot. In order to facilitate the handling of such a huge amount of data, an advanced data reduction scheme is being developed. Remote operation with a fast data link from FZ Jülich (Germany) to FOM Nieuwegein (The Netherlands) will be possible. © 1999 American Institute of Physics.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1063/1.1149426
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  • 59
    Digitale Medien
    Digitale Medien
    Thermal noise in a high Q cryogenic resonator (1999)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 70 (1999), S. 1851-1856 
    Details
    ISSN: 1089-7623
    Quelle: AIP Digital Archive
    Thema: Physik , Elektrotechnik, Elektronik, Nachrichtentechnik
    Notizen: In order to evaluate the feasibility of a mixed mechanical and electrical multimode matching network for a resonant gravitational wave detector, current noise measurements were performed on a high quality factor inductance–capacitance resonator, based on a superconducting coil, by using a dc superconducting quantum interference device weakly coupled to the coil. We present a method to identify different noise sources in the system by their dependence on the temperature or on the resonator quality factor. Measurements performed at quality factors up to 106 in the temperature range 1.2–4.2 K, show that the total measured noise is only contributed by the resonator thermal noise. © 1999 American Institute of Physics.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1063/1.1149679
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  • 60
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    Digitale Medien
    A 6 kV–150 A, 8 ns rise time pulse generator for excitation of ferroelectric cathodes (1999)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 70 (1999), S. 1857-1859 
    Details
    ISSN: 1089-7623
    Quelle: AIP Digital Archive
    Thema: Physik , Elektrotechnik, Elektronik, Nachrichtentechnik
    Notizen: A pulse generator with the following characteristics is presented: the voltage ranges in the interval 0.1–6 kV, the maximum delivered current is 150 A, the pulse length ranges within the interval 100–300 ns, the rise time and the decay times are, respectively, 10 and 25 ns on 50 Ω resistive load and the repetition rate is higher than 1 MHz. The circuit has a source capacitor of 10 nF charged at the needed voltage, the capacitor feeds the load through a parallel of two fast and high voltage solid state switches. The nanosecond rise time and the square fashion of the pulse have been accomplished arranging all the components in cylindrical symmetry. A bipolar pulse is obtained coupling two circuits with opposite polarity. © 1999 American Institute of Physics.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1063/1.1149680
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  • 61
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    Digitale Medien
    Thermally actuated interferometric sensors based on the thermal expansion of transparent elastomeric media (1999)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 70 (1999), S. 2031-2037 
    Details
    ISSN: 1089-7623
    Quelle: AIP Digital Archive
    Thema: Physik , Elektrotechnik, Elektronik, Nachrichtentechnik
    Notizen: In this article the fabrication and characterization of two thermally actuated optical devices for the measurement of temperature and power are described. A transparent polymer having a high coefficient of thermal expansion—poly(dimethylsiloxane) (PDMS)—was used as the temperature-sensitive medium. Changes in the dimensions of the polymer on heating caused the observed optical responses of both devices. The temperature sensor based on the Fabry–Pérot cavity measures temperature differences to a precision of 0.005 °C within the linear working ranges of the device. The power sensor uses the architecture of a Mach–Zender interferometer; it is suitable for measurements of powers in the mW/cm2 range, delivered optically to the surface of the device in the visible wavelength region. The devices are inexpensive, easy to fabricate, and mechanically rugged. They offer alternatives to other sensors for measuring temperature and power. © 1999 American Institute of Physics.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1063/1.1149706
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  • 62
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    Digitale Medien
    High magnetic field corrections to resistance thermometers at low temperatures (1999)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 70 (1999), S. 2026-2030 
    Details
    ISSN: 1089-7623
    Quelle: AIP Digital Archive
    Thema: Physik , Elektrotechnik, Elektronik, Nachrichtentechnik
    Notizen: We present a reliable method to account for the magnetoresistance of resistance sensors which are used as thermometers in many low temperature (T≤20 K) experiments carried out in high magnetic fields (to 31 T). To apply the method, a set of isothermal magnetoresistance data, and a zero magnetic field temperature calibration are first necessary. A simple algorithm, which uses this data set, can then be applied to compute the temperature from the measured resistance at any field. The method is particularly useful for temperature dependent measurements at fixed field, or where, in cases where the temperature may change unpredictably during a change in magnetic field. We apply this method to the treatment of data in two separate experiments with the two different thermometers, RuO2 (below 1 K) and Cernox (above 1 K) sensors, respectively. © 1999 American Institute of Physics.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1063/1.1149705
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  • 63
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    Digitale Medien
    Effect of an input coil microwave resonance on dynamics and noise properties of a dc superconducting quantum interference device operating close to the hysteretic mode (1999)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 70 (1999), S. 1713-1718 
    Details
    ISSN: 1089-7623
    Quelle: AIP Digital Archive
    Thema: Physik , Elektrotechnik, Elektronik, Nachrichtentechnik
    Notizen: The dynamics and noise of a dc superconducting quantum interference device (SQUID) with the McCumber parameter βc=2πR2IcC/Φ0 close to the unity (where Ic, R, C are the critical current, the shunt resistance, and the capacitance of the Josephson junctions comprising the SQUID, respectively, and Φ0=2.07×10−15 Wb is the magnetic flux quantum) integrated with a planar spiral input coil have been experimentally studied. The length of the spiral input coil was chosen to match its λ/4 microwave resonance frequency to the plasma resonance frequency of the SQUID. The input coil resonance enhances the overall quality factor Q of the Josephson oscillations in the SQUID and, as a result, increases the dynamic resistance Rd and the gradient of the flux-to-voltage characteristics ∂V/∂Φ without hysteresis. This relaxes the tolerance for the βc parameter, simplifies the technological process, and improves the yield of devices. A dc SQUID with loop inductance L=31.4 pH, βc=0.72, and a six turn input coil has demonstrated a nondistorted quasisinusoidal flux-to-voltage transfer function with an exceptionally large modulation depth of approximately 140 μV peak-to-peak. A spectral density of the intrinsic magnetic flux noise as low as 3.5×10−7 Φ0/Hz1/2 has been measured in the double stage configuration at a temperature of 4.2 K using direct read-out electronics. This corresponds to the intrinsic energy resolution of ε=12.5h. In combination with an intermediary transformer, the current resolution of the SQUID is as low as 1.25 pA/Hz1/2 with an input coil inductance of 58 nH. The coupled energy resolution is εc=45h in the white noise region. © 1999 American Institute of Physics.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1063/1.1149656
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  • 64
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    Digitale Medien
    A slit grating spectrograph for quantitative soft x-ray spectroscopy (1999)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 70 (1999), S. 1694-1699 
    Details
    ISSN: 1089-7623
    Quelle: AIP Digital Archive
    Thema: Physik , Elektrotechnik, Elektronik, Nachrichtentechnik
    Notizen: In this article we describe a new slit grating spectrograph which is based on an e-beam written 10 000 linepairs/mm freestanding transmission diffraction grating. In combination with a thinned, back-illuminated charge coupled device (CCD), the spectrograph allows for real-time spectroscopy of laser-produced plasma x-ray sources within the wavelength region λ=1–20 nm. Calibration of grating and CCD allow for the possibility to measure absolute photon fluxes, currently within the wavelength region λ=1–6 nm. The compact spectrograph is easy to align and flexible in its use. Absolutely calibrated spectra were obtained from a liquid-jet laser-plasma source in the water window, with a spectral resolution λ/Δλ≥330 at λ=3.37 nm. A simple change in experimental geometry allowed single-shot spectra to be recorded with λ/Δλ≥60 at the same wavelength. In addition, spectra from this laser-plasma source were measured within the range λ=9–20 nm. © 1999 American Institute of Physics.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1063/1.1149653
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  • 65
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    Digitale Medien
    Controlling chaotic systems with occasional proportional feedback (1999)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 70 (1999), S. 1719-1724 
    Details
    ISSN: 1089-7623
    Quelle: AIP Digital Archive
    Thema: Physik , Elektrotechnik, Elektronik, Nachrichtentechnik
    Notizen: Utilizing the chaos control technique of occasional proportional feedback (OPF), we designed and constructed an inexpensive and easy to assemble electronic OPF controller. A number of built-in features provide ample versatility to enable the controller to be used with a wide variety of chaotic experimental systems. The controller has a standard OPF correction signal output, but also allows for the addition of a modulated signal to the correction. The rate and active duration of the correction pulse, the offset voltage, and the effective window width are variable. We present the basic principles of OPF control and discuss the individual component functions of the OPF controller. We have successfully used this controller to stabilize chaotic fluctuations in the frequency emission from a tunable lead–salt stripe geometry infrared diode laser. © 1999 American Institute of Physics.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1063/1.1149657
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  • 66
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    Digitale Medien
    Angle chord integral inverter and a rotating type optical probe (1999)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 70 (1999), S. 1730-1734 
    Details
    ISSN: 1089-7623
    Quelle: AIP Digital Archive
    Thema: Physik , Elektrotechnik, Elektronik, Nachrichtentechnik
    Notizen: The inversion problem of angle dependent chord integrals is theoretically studied and a rotating type optical probe is developed for its application. The proposed solution is computationally efficient and robust to measurement additive noise. The probe system constructed is tested in an inductively coupled plasma source by measuring a spectral line intensity of argon plasma. © 1999 American Institute of Physics.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1063/1.1149659
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  • 67
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    Digitale Medien
    0.4 μm spatial resolution with 1 GHz (λ=30 cm) evanescent microwave probe (1999)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 70 (1999), S. 1725-1729 
    Details
    ISSN: 1089-7623
    Quelle: AIP Digital Archive
    Thema: Physik , Elektrotechnik, Elektronik, Nachrichtentechnik
    Notizen: In this article we describe evanescent field imaging of material nonuniformities with a record resolution of 0.4 μm at 1 GHz (λg/750 000), using a resonant stripline scanning microwave probe. A chemically etched tip is used as a point-like evanescent field emitter and a probe–sample distance modulation is employed to improve the signal-to-noise ratio. Images obtained by evanescent microwave probe, by optical microscope, and by scanning tunneling microscope are presented for comparison. Probe was calibrated to perform quantitative conductivity measurements. The principal factors affecting the ultimate resolution of evanescent microwave probe are also discussed. © 1999 American Institute of Physics.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1063/1.1149658
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  • 68
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    Digitale Medien
    MEPHISTO spectromicroscope reaches 20 nm lateral resolution (1999)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 70 (1999), S. 1740-1742 
    Details
    ISSN: 1089-7623
    Quelle: AIP Digital Archive
    Thema: Physik , Elektrotechnik, Elektronik, Nachrichtentechnik
    Notizen: The recently described tests of the synchrotron imaging photoelectron spectromicroscope MEPHISTO (Microscope à Emission de PHotoélectrons par Illumination Synchrotronique de Type Onduleur) were complemented by further resolution improvements and tests, which brought the lateral resolution down to 20 nm. Images and line plot profiles demonstrate such performance. © 1999 American Institute of Physics.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1063/1.1149661
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  • 69
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    Digitale Medien
    Vibrating reed apparatus with optical detection and digital signal processing: Application to measurements on thin films (1999)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 70 (1999), S. 1751-1755 
    Details
    ISSN: 1089-7623
    Quelle: AIP Digital Archive
    Thema: Physik , Elektrotechnik, Elektronik, Nachrichtentechnik
    Notizen: We present an apparatus that permits quasisimultaneous measurements of several vibrating modes in a vibrating reed experiment. Position detection by laser beam deflection offers a simple setup and good sensitivity for higher modes of flexural as well as torsional vibrations. Frequency and damping from free decay data are determined by software which permits high accuracy, especially at low damping. This is particularly interesting for the measurement of the mechanical properties of thin films deposited on a low damping vibrating reed. As an example results on an Al film on a microstructurized silicon resonator are shown. © 1999 American Institute of Physics.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1063/1.1149663
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  • 70
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    Digitale Medien
    Picosecond time-resolved electronic spectroscopy in plate impact shock experiments: Experimental development (1999)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 70 (1999), S. 1743-1750 
    Details
    ISSN: 1089-7623
    Quelle: AIP Digital Archive
    Thema: Physik , Elektrotechnik, Elektronik, Nachrichtentechnik
    Notizen: An experimental method was developed to perform picosecond time-resolved electronic spectroscopy in single-event, plate impact, shock wave experiments. Several experimental difficulties had to be addressed due to the fast time resolution (100 ps) and short time duration (12.7 ns) of such experiments. Procedures are described to address the following experimental issues: (i) synchronization of the light source, detection equipment, and the shock event within the experimental duration, (ii) incorporation of a Nd:YAG laser (operative in a repetitive mode) into the experimental configuration, and (iii) sources of temporal dispersion. Representative results are shown from experiments performed on single crystal CdS. The developments described here are also expected to be useful for shock wave experiments involving Raman, fluorescence, or other types of spectroscopy which require the use of a laser. © 1999 American Institute of Physics.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1063/1.1149662
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  • 71
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    Digitale Medien
    Practical aspects of Kelvin probe force microscopy (1999)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 70 (1999), S. 1756-1760 
    Details
    ISSN: 1089-7623
    Quelle: AIP Digital Archive
    Thema: Physik , Elektrotechnik, Elektronik, Nachrichtentechnik
    Notizen: We discuss practical aspects of Kelvin probe force microscopy (KFM) which are important to obtain stable images of the electric surface potential distribution at high spatial resolution (〈100 nm) and high potential sensitivity (〈1 mV) on conducting and nonconducting samples. We compare metal-coated and semiconducting tips with respect to their suitability for KFM. Components of the metal coating can become detached during scanning, introducing sudden offset jumps in the potential maps (typically up to 350 mV between adjacent scan lines). However, n-doped silicon tips show no substantial tip alterations and, therefore, provide a stable reference during the experiment (offset jumps typically up to 40 mV between adjacent scan lines). These semiconducting tips must be electrically connected via contact pads. We use InGa and colloidal silver pads which are easily applied to the substrate supporting the cantilever and have a low enough differential contact resistance (350 Ω and 2.2 kΩ, respectively). Furthermore, we introduce a simple procedure to fine tune the feedback which detects the electric surface potential and show how the basic KFM setup has to be modified to gain access to the necessary control signals. © 1999 American Institute of Physics.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1063/1.1149664
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  • 72
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    Digitale Medien
    Neutron monitor using microfission chambers for the International Thermonuclear Experimental Reactor : Proceedings of the 12th topical conference on high temperature plasma diagnostics (1999)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 70 (1999), S. 1141-1144 
    Details
    ISSN: 1089-7623
    Quelle: AIP Digital Archive
    Thema: Physik , Elektrotechnik, Elektronik, Nachrichtentechnik
    Notizen: We are designing microfission chambers, which are pencil size gas counters with fissile material inside, to be installed in the vacuum vessel as neutron flux monitors for the International Thermonuclear Experimental Reactor (ITER). We computed the neutron and gamma flux around the shielding blanket by a two-dimensional neutron calculation, in order to find suitable locations for microfission chambers. We found that the 238U microfission chambers are not suitable because the detection efficiency will increase up to 50% during the ITER lifetime by breeding 239U. We propose to install 235U microfission chambers on the front side of the back plate in the gap between adjacent blanket modules and behind the blankets at ten poloidal locations. One chamber will be installed in the divertor cassette, just under the dome. Employing both the pulse counting mode and Campbelling mode in the electronics, we can accomplish the ITER requirement of 107 dynamic range, with 1 ms temporal resolution, and eliminate the effect of gamma rays. An in-vessel neutron monitor will be affected by changes of the detection efficiency due to the change in the plasma position and neutron source profile. Here we demonstrate by neutron Monte Carlo calculation with three-dimensional modeling that we avoid those detection efficiency changes by installing microfission chambers at several poloidal locations inside the vacuum vessel. © 1999 American Institute of Physics.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1063/1.1149297
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  • 73
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    Digitale Medien
    Linewidth measurements of the JET energetic ion and alpha particle collective Thomson scattering diagnostic gyrotron : Proceedings of the 12th topical conference on high temperature plasma diagnostics (1999)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 70 (1999), S. 1154-1157 
    Details
    ISSN: 1089-7623
    Quelle: AIP Digital Archive
    Thema: Physik , Elektrotechnik, Elektronik, Nachrichtentechnik
    Notizen: Spectral purity of the transmitter source of a collective Thomson scattering (CTS) system is vitally important to insure that measured signals only originate from the plasma and not from stray source light. A number of high power (up to 500 kW), 140 GHz gyrotron tubes used with the Joint European Torus (JET) CTS system have been found to have one or more spurious modes and many harmonics in the output spectrum. The CTS diagnostic receiver system was used to make measurements of the gyrotron spectrum. It was comprised of a homodyne part from MIT for frequency sidebands 〈500 MHz, and a heterodyne part constructed at JET for frequency sidebands from 0.1 to 6 GHz. One tube at high power produced a strong 25 MHz mode and its harmonics to large frequency offsets, unsuitable for CTS measurements. Only at reduced power of approximately 100 kW was this tube's spectrum sufficiently clean for CTS. Another tube at JET operated at 500 kW output power with only low level parasitic modes, indicating that higher power gyrotrons may be available for future alpha particle measurements. The main receiver was tested with a low power test setup which simulated the gyrotron stray source light, the thermal ion feature and plasma electron cyclotron emission. © 1999 American Institute of Physics.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1063/1.1149580
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  • 74
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    Digitale Medien
    A cost-effective method for minimizing the sphere-of-confusion error of x-ray microdiffractometers (1999)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 70 (1999), S. 1300-1304 
    Details
    ISSN: 1089-7623
    Quelle: AIP Digital Archive
    Thema: Physik , Elektrotechnik, Elektronik, Nachrichtentechnik
    Notizen: Microdiffractometers are used to obtain x-ray diffraction data from regions that are tens of microns or less in size. If a microdiffractometer's rotation circles do not share the same center, or if the feature of interest on a sample does not lie at the center of all rotations, the sample feature will, upon rotation of the diffractometer circles, precess through a finite volume known as the sphere of confusion (SoC). If the size of the beam used for diffraction analysis is smaller than the SoC diameter, the beam may actually move off the region of interest. In this article, we describe a new technique, based on x-ray fluorescence imaging and coordinate transforms, which can maintain the sample position to within ±6 μm over all rotations even when a commercial diffractometer is used as the base for the microdiffractometer system. In this scheme, a grid held in place on the specimen surface is mapped using fluorescent radiation at various sample tilts. The transformation matrices, which relate the grid coordinates to the sample stage coordinates at different sample tilts, can then be used to bring the sample stage into coincidence with its original position. © 1999 American Institute of Physics.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1063/1.1149588
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  • 75
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    Digitale Medien
    Cavity ring down spectroscopy on radicals in a supersonic slit nozzle discharge (1999)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 70 (1999), S. 1305-1312 
    Details
    ISSN: 1089-7623
    Quelle: AIP Digital Archive
    Thema: Physik , Elektrotechnik, Elektronik, Nachrichtentechnik
    Notizen: A sensitive and generally applicable technique for direct absorption spectroscopy on electronic transitions of transient species in the gas phase is presented. The method is based on cavity ring down spectroscopy in a pulsed slit nozzle, incorporating a discharge in a high pressure supersonic expansion. The performance is demonstrated with spectra of the 000 origin band of the 2Π←X2Π electronic transition of the isoelectronic linear carbon chain radicals C6H and C6H2+. Rotationally resolved and rotationally cold spectra (Trot〈15 K) have been obtained. The sensitivity of the technique is demonstrated for anions with a detection limit as low as 107 C2− molecules cm−3 for rovibrational transitions of the B2Σu+←X2Σg+ system. © 1999 American Institute of Physics.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1063/1.1149589
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  • 76
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    Digitale Medien
    New design of a cryostat-mounted scanning near-field optical microscope for single molecule spectroscopy (1999)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 70 (1999), S. 1318-1325 
    Details
    ISSN: 1089-7623
    Quelle: AIP Digital Archive
    Thema: Physik , Elektrotechnik, Elektronik, Nachrichtentechnik
    Notizen: Due to the weakness of the fluorescence signal from a single fluorophore, a scanning near-field optical microscope for single molecule spectroscopy requires a very efficient setup for the collection and detection of emitted photons. We have developed a home-built microscope for operation in a l-He cryostat which uses a solid parabolic mirror in order to optimize the fluorescence collection efficiency. This microscope works with Al-coated, tapered optical fibers in illumination mode. The tip-sample separation is probed by an optical shear-force detection. First results demonstrate the capability of the microscope to image single molecules and achieve a topographical resolution of a few nanometers vertically and better than 50 nm laterally. © 1999 American Institute of Physics.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1063/1.1149591
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  • 77
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    Digitale Medien
    Compact and freely movable single atom detector (1999)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 70 (1999), S. 1326-1332 
    Details
    ISSN: 1089-7623
    Quelle: AIP Digital Archive
    Thema: Physik , Elektrotechnik, Elektronik, Nachrichtentechnik
    Notizen: A compact fluorescence detector has been developed which allows to count slow, single Na atoms. By using glass fibers for the exciting and the fluorescence light we obtained free movability of the detector. The detection efficiency has been analyzed and optimized by an extensive investigation of all processes concerning the laser-induced fluorescence, especially the random walk of the atom, saturation effects, and optical pumping. Single atoms are identified by registration of photon bursts which stand out from the Poisson distributed background. An absolute calibration of the detection efficiency has been achieved by a time-resolved fluorescence measurement in combination with a corresponding Monte–Carlo simulation. Atomic fluxes well below 1 atom/s can be determined with an uncertainty of less than ±10%. Assuming a continuous flux of 1 atom/s with 25 m/s typically about 50% of these atoms are counted. The detector is an excellent tool for differential scattering experiments with slow atomic beams. © 1999 American Institute of Physics.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1063/1.1149592
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  • 78
    Digitale Medien
    Digitale Medien
    A trimodal resonator for three mutually perpendicular magnetic fields (1999)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 70 (1999), S. 1780-1786 
    Details
    ISSN: 1089-7623
    Quelle: AIP Digital Archive
    Thema: Physik , Elektrotechnik, Elektronik, Nachrichtentechnik
    Notizen: We describe a trimodal resonator for the simultaneous delivery of three perpendicular magnetic fields. The resonator consists of a shielded loop single-mode radio frequency (rf) resonator placed inside of a bimodal waveguide microwave resonator. The microwave modes are nondegenerate, tunable over a range of 100 MHz, and have typical Q factors of 150 and 200. The rf mode is tunable over a range of 125 MHz, and has a typical Q of 45. Control of the relative phase between the three fields is demonstrated. The resonator will be used to drive three magnetic dipole transitions coherently between Zeeman states in the ground state of 87Rb. © 1999 American Institute of Physics.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1063/1.1149668
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  • 79
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    Digitale Medien
    Measurements of charged-particle fusion yields and ratios from Omega (abstract) : Proceedings of the 12th topical conference on high temperature plasma diagnostics (1999)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 70 (1999), S. 1225-1225 
    Details
    ISSN: 1089-7623
    Quelle: AIP Digital Archive
    Thema: Physik , Elektrotechnik, Elektronik, Nachrichtentechnik
    Notizen: We have recently conducted a series of experiments on Omega in which we utilized a charged-particle spectrometer. It consists of a 7.6 kG magnet, CR-39 track for particle detection, and an assortment of range filters to either discriminate against or emphasize certain particles. Because of excellent particle selectivity and energy resolution, the spectrometer can accurately measure the ratios of various fusion products from a single shot. Among other uses, these ratios will be used to determine ion temperatures.© 1999 American Institute of Physics.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1063/1.1149458
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  • 80
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    Digitale Medien
    Long atomic imaging over a 5-μm-long region using an ultralow thermally drifted dual-tunneling-unit scanning tunneling microscope in a thermostabilized cell (1999)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 70 (1999), S. 133-136 
    Details
    ISSN: 1089-7623
    Quelle: AIP Digital Archive
    Thema: Physik , Elektrotechnik, Elektronik, Nachrichtentechnik
    Notizen: This article describes the feasibility evaluation of long atomic imaging over a 5-μm-long region for the comparative length measurement using a crystalline lattice as the reference scale and a dual-tunneling-unit scanning tunneling microscope (DTU-STM) as a detector. For suppression of the thermal deformation error, ultralow thermally drifted DTU-STM was developed. The body of the DTU-STM is fabricated from ultralow linear expansion glass and Super-Invar. A thermostabilized cell was utilized to reduce the temperature fluctuation to less than 0.05 K around the DTU-STM. In the thermostabilized cell, the minimum lateral element of thermal drift rate of less than 0.2 nm/h at room temperature was achieved with the DTU-STM. In order to decrease the measurement time and thus reduce the thermal drift error, the fast scanning axis was selected as the direction of the length measurement over the μm range. After attaining thermal equilibrium, a long atomic image of highly oriented pyrolytic graphite over a 5-μm-long region along the fast scanning axis was obtained using the DTU-STM in the thermostabilized cell. © 1999 American Institute of Physics.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1063/1.1149554
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  • 81
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    Digitale Medien
    An automated, externally heated opposed anvil high pressure–high temperature system for electrical resistivity studies (1999)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 70 (1999), S. 165-170 
    Details
    ISSN: 1089-7623
    Quelle: AIP Digital Archive
    Thema: Physik , Elektrotechnik, Elektronik, Nachrichtentechnik
    Notizen: A simple, externally heated opposed (Bridgman) anvil system has been developed for electrical resistivity measurements up to 8 GPa pressure and 400 °C. The whole system is automated, in which the application and measurement of pressure and heating of the sample are undertaken using an IBM PC and associated electronic and mechanical hardware. The system developed has a pressure control of about ±1% and temperature control better than ±2%. The setup has been calibrated using the high pressure–high temperature transitions in the electrical resistivity of Bi and Yb. The usefulness of the system developed has been demonstrated, by studying the resistivity behavior of glassy chalcogenide semiconductors at high pressure and high temperature. © 1999 American Institute of Physics.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1063/1.1149559
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  • 82
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    Digitale Medien
    Magnetic detection of cracks by fatigue in mild steels using a scanning Hall-sensor microscope (1999)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 70 (1999), S. 184-186 
    Details
    ISSN: 1089-7623
    Quelle: AIP Digital Archive
    Thema: Physik , Elektrotechnik, Elektronik, Nachrichtentechnik
    Notizen: We fabricated a scanning Hall-sensor microscope with an active area 50 μm×50 μm that can be served as a simple and conventional tool for nondestructive evaluation of magnetic materials. Using this, we succeeded in magnetic detection of small cracks (∼10 mm long and ∼0.1 mm wide) in mild steels with a yield point of 29 kgf/mm2, caused by a plane-bending fatigue test at a stress amplitude of 28 kgf/mm2 and a frequency of 29.2 Hz. © 1999 American Institute of Physics.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1063/1.1149563
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  • 83
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    Digitale Medien
    Photoacoustic measurement of intracavity energy in pulsed lasers (1999)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 70 (1999), S. 1-3 
    Details
    ISSN: 1089-7623
    Quelle: AIP Digital Archive
    Thema: Physik , Elektrotechnik, Elektronik, Nachrichtentechnik
    Notizen: We show that the photoacoustic signals generated at the high reflection mirror of a pulsed laser depend linearly on the output energy. This allows us to measure acoustically the output energy, the tuning range, and the optimum temperature and concentration of a dye laser, with the advantage that there is no interference of the output beam, as is the case with optical measurements. © 1999 American Institute of Physics.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1063/1.1149479
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  • 84
    Digitale Medien
    Digitale Medien
    Very high frequency and microwave interferometric phase and amplitude noise measurements (1999)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 70 (1999), S. 220-225 
    Details
    ISSN: 1089-7623
    Quelle: AIP Digital Archive
    Thema: Physik , Elektrotechnik, Elektronik, Nachrichtentechnik
    Notizen: The interferometric technique allows close-to-the-carrier measurements of both phase and amplitude noise, improving the instrument noise floor by 10–25 dB as compared to the traditional method based on a saturated mixer. Principles and basic equations describing the noise measurement system are given, together with design strategies suitable to microwave and very high frequency bands. Two prototypes, operating at 9 GHz and 100 MHz are discussed in detail. The relevant features of these prototypes are the capability to operate in a wide power range, below 0 dBm and above 20 dBm, and low noise floor. The latter is about −180 dB rad2/Hz (white) and 150 dB rad2/Hz (flicker) at 1 Hz Fourier frequency, at carrier power from 9 to 15 dBm. © 1999 American Institute of Physics.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1063/1.1149351
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  • 85
    Digitale Medien
    Digitale Medien
    A stopped-flow apparatus with a push–pull coupler for the study of fast reactions in solution under high pressure (1999)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 70 (1999), S. 244-245 
    Details
    ISSN: 1089-7623
    Quelle: AIP Digital Archive
    Thema: Physik , Elektrotechnik, Elektronik, Nachrichtentechnik
    Notizen: A new high-pressure stopped-flow apparatus equipped with a push–pull coupler has been developed which enables one to monitor fast reactions in various organic solvents as well as in strongly acidic media under pressure up to 200 MPa. Sample solutions come into contact only with chemically inert materials: Daiflon, quartz, and a Teflon-coated O-ring. The reactant-syringe and receiver-syringe pistons are driven at the same time with the aid of a push–pull coupler and an actuator. The dead time of this apparatus is ∼2 ms. © 1999 American Institute of Physics.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1063/1.1149574
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  • 86
    Digitale Medien
    Digitale Medien
    Wide-band, high-resolution soft x-ray spectrometer for the Electron Beam Ion Trap : Proceedings of the 12th topical conference on high temperature plasma diagnostics (1999)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 70 (1999), S. 280-283 
    Details
    ISSN: 1089-7623
    Quelle: AIP Digital Archive
    Thema: Physik , Elektrotechnik, Elektronik, Nachrichtentechnik
    Notizen: We have constructed two wide-band, high-resolution vacuum flat crystal spectrometers and implemented them on the Electron Beam Ion Trap located at the Lawrence Livermore National Laboratory. Working in unison, these spectrometers can measure an x-ray bandwidth ≤9 Å in the soft x-ray region below 21 Å. In order to achieve this large bandwidth each spectrometer houses either two 125 mm × 13 mm × 2 mm RAP (rubidium acid phthalate, 2d=26.121 Å), two 114 mm × 13 mm × 2 mm TlAP (thallium acid phthalate, 2d=25.75 Å) crystals, or some combination thereof, for dispersion and two position sensitive proportional counters for detection of x rays. The spectrometers are used to measure wavelengths and relative intensities of the L-shell line emission from Fe XVII–XXIV for comparison with spectra obtained from astrophysical and laboratory plasmas. The wide wavelength coverage attainable by these spectrometers makes it possible to measure all the L-shell emission from a given iron ion species simultaneously. © 1999 American Institute of Physics.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1063/1.1149339
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  • 87
    Digitale Medien
    Digitale Medien
    Electron trapping materials for use in a picosecond infrared streak camera (1999)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 70 (1999), S. 4482-4486 
    Details
    ISSN: 1089-7623
    Quelle: AIP Digital Archive
    Thema: Physik , Elektrotechnik, Elektronik, Nachrichtentechnik
    Notizen: We describe our research on the employment of an infrared upconversion screen made of electron trapping material (ETM) in combination with the high sensitivity of the S-20 photocathode responsive to visible radiation to produce a streak camera arrangement capable of viewing and recording infrared incident pulses. The ETM-based upconversion screen converts 800–1600 nm infrared radiation to visible light which is viewed or recorded by the S-20 photocathode. The peak values of the upconversion efficiency are located at 1165 nm for CaS:Eu, Sm and 1060 nm for CaS:Ce, Sm. The present experiment showed time resolution was 12.3 ps for a CaS:Eu, Sm screen and 8.4 ps for a CaS:Ce, Sm screen. The minimum detectability is 4.8×10−9 J/mm2 (minimum detectability of the coupled visible streak camera is 8.3×10−10 J/mm2). Other parameters, such as spatial resolution and dynamic range, have also been measured and analyzed. The results show ETM can be used in the measurement of infrared ultrafast phenomena up to picosecond time domain. In consideration of the limited number of trapped electrons in ETM, the infrared-sensitive streak camera consisting of an ETM-based upconversion screen is suitable to operate in the single shot mode. © 1999 American Institute of Physics.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1063/1.1150100
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  • 88
    Digitale Medien
    Digitale Medien
    Simultaneous energy distribution and ion fraction measurements using a linear time-of-flight analyzer with a floatable drift tube (1999)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 70 (1999), S. 4515-4522 
    Details
    ISSN: 1089-7623
    Quelle: AIP Digital Archive
    Thema: Physik , Elektrotechnik, Elektronik, Nachrichtentechnik
    Notizen: A technique for simultaneous energy distribution and ion fraction measurements using a linear time-of-flight analyzer with a floatable drift tube is described. Analytical expressions for the relative collection efficiency and viewing region of the apparatus are developed as functions of the analyzed particle reduced energy and dimensionless apparatus parameters. The method was applied to studies of large-angle scattering of singly charged oxygen ions incident on Au(110), and carried out at the Oak Ridge National Laboratory's Multicharged Ion Research Facility. Energy distributions of the scattered projectiles and the negative ion fraction are presented as a function of scattered projectile energy. As a by-product of the measurements, the relative ion detection efficiency of the particle detector was reconstructed as a function of ion impact energy on the detector. © 1999 American Institute of Physics.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1063/1.1150104
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  • 89
    Digitale Medien
    Digitale Medien
    Variable geometry two mode levitation trap (1999)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 70 (1999), S. 4231-4233 
    Details
    ISSN: 1089-7623
    Quelle: AIP Digital Archive
    Thema: Physik , Elektrotechnik, Elektronik, Nachrichtentechnik
    Notizen: Construction and operation of the electrodynamic levitation trap which can be operated in a passive and an active mode is described. This combination together with variable electrode geometry simplifies the trap's design and simultaneously gives more flexibility with respect to different kinds of measurements. Sample measurements of mechanocaloric effect caused by nonuniform heating of a single levitated particle are presented and discussed. © 1999 American Institute of Physics.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1063/1.1150057
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  • 90
    Digitale Medien
    Digitale Medien
    Optimization of spherical deflecting analyzer with finite-size effects (1999)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 70 (1999), S. 4213-4220 
    Details
    ISSN: 1089-7623
    Quelle: AIP Digital Archive
    Thema: Physik , Elektrotechnik, Elektronik, Nachrichtentechnik
    Notizen: Spherical analyzers have been widely used in electron spectroscopy due to their high energy resolution. In this article, we present a way of optimizing the performance of a 90° spherical deflecting analyzer (SDA-90) considering finite-source effects, using an imaging matrix formalism. Results are shown for both symmetrically and asymmetrically charged cases. The asymmetrical case is found to be superior both in transmission and resolution. This unexpected advantage can be explained by the rotation of the image caused by the broken symmetry along the principle trajectory in the analyzer using an asymmetrical potential configuration. The net effect is equivalent to a reduction in the lateral magnification and a gain in energy dispersion. Both factors improve the performance of the analyzer. The fringe fields, carefully controlled by two Herzog lenses, are very important in the optimization. A telefocus electron gun is used to check the numerical result, and to investigate the transverse focusing behavior. © 1999 American Institute of Physics.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1063/1.1150054
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  • 91
    Digitale Medien
    Digitale Medien
    Generation and characterization of high intensity electron beams generated from rough photocathodes (1999)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 70 (1999), S. 4221-4224 
    Details
    ISSN: 1089-7623
    Quelle: AIP Digital Archive
    Thema: Physik , Elektrotechnik, Elektronik, Nachrichtentechnik
    Notizen: In this work, the generation and the characterization of high current electron beams from rough photocathodes induced by an ultraviolet excimer laser are reported. The cathodes were rough Cu disks. In order to study the influence of the cathode surface, the electron emission from different surface roughnesses was investigated. To establish the electromagnetic and geometric parameters a Rogowski coil and a new slit–slit emittance meter were used. The laser beam utilized was obtained by a mixture of Kr and Cl which generated coherent light at 222 nm. Fixing the laser energy at 0.5 mJ and the laser spot into 4 mm2, the maximum current as well as the maximum emittance value were obtained with the cathode that had the highest surface roughness which resulted in 1 A and 46 π mm mrad, respectively. A low current and a low emittance were obtained with the cathode that had the lowest roughness, namely, 410 mA and 19 π mm mrad, respectively. A quantum efficiency value of 1.2×10−4 was reached with the cathode with the highest amount of roughness. © 1999 American Institute of Physics.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1063/1.1150055
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  • 92
    Digitale Medien
    Digitale Medien
    The drift source: A negative ion source module for direct current multiampere ion beams (1999)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 70 (1999), S. 4542-4544 
    Details
    ISSN: 1089-7623
    Quelle: AIP Digital Archive
    Thema: Physik , Elektrotechnik, Elektronik, Nachrichtentechnik
    Notizen: The concept of a modular large size ion source is under investigation in our laboratory for the development of the very intense (tens of amperes) negative ion (D−) beams needed for neutral beam injection in thermonuclear fusion research. The basic idea is to develop a compact small ion source producing the required ion flux (20–30 mA/cm2) over a total surface of about 200 cm2 and designed in such a way that it can easily be juxtaposed with other identical modules. A large negative ion source of any size (up to several m2) and shape could be realized as a set of several modules. The anticipated advantage of this concept is the minimization of the risk inherent in a large extrapolation in size (e.g., (approximate)1.0 m2 for an ignition device to test engineering concepts) of the present ion sources. In this context, we have developed and tested a source module, called the DRIFT source, whose main properties are presented in this article. The particular magnetic field configuration of this module ensures, in a simplified way, a very good plasma confinement allowing operation of the source at very low filling pressures. Up to now, a D− current of 1 A (20 mA/cm2) 50 keV energy, 1 s pulse length, was obtained with cesium vapor seeding at 0.15 Pa source pressure with an arc power of 2.5 kW/l (12 kW). © 1999 American Institute of Physics.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1063/1.1150109
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  • 93
    Digitale Medien
    Digitale Medien
    Nonstationary signal analysis of magnetic islands in plasmas (1999)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 70 (1999), S. 4545-4551 
    Details
    ISSN: 1089-7623
    Quelle: AIP Digital Archive
    Thema: Physik , Elektrotechnik, Elektronik, Nachrichtentechnik
    Notizen: Rotating magnetic islands produce fluctuations on a variety of diagnostics in magnetic fusion energy plasmas. The analysis of these fluctuations requires the calculation of the amplitude, phase, and frequency of the oscillations. These three spectral quantities generally evolve in time, necessitating nonstationary signal analysis techniques. The Hilbert transform offers an efficient and accurate method of calculating these three quantities from one diagnostic signal. This feature allows the Hilbert transform to determine the success of the active rotation control of magnetic islands, and to calculate the profile of the diagnostic measurements in a frame of reference co-rotating with the magnetic island. Comparisons to quadrature and spectrogram techniques demonstrate the accuracy of the Hilbert transform method. © 1999 American Institute of Physics.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1063/1.1150110
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  • 94
    Digitale Medien
    Digitale Medien
    Portable oil bath for high-accuracy resistance transfer and maintenance (1999)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 70 (1999), S. 3938-3941 
    Details
    ISSN: 1089-7623
    Quelle: AIP Digital Archive
    Thema: Physik , Elektrotechnik, Elektronik, Nachrichtentechnik
    Notizen: A portable oil bath containing one standard resistor for high-accuracy resistance transfer and maintenance was developed and operated for seven years in the National Research Laboratory of Metrology. The aim of the bath is to save labor and apparatus for high-accuracy resistance transfer and maintenance by consistently keeping the standard resistor in an optimum environmental condition. The details of the prototype system, including its performance, are described together with some suggestions for a more practical bath design, which adopts the same concept. © 1999 American Institute of Physics.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1063/1.1150016
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  • 95
    Digitale Medien
    Digitale Medien
    Gas flow meter using a positive temperature coefficient thermistor as the sensor (1999)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 70 (1999), S. 3949-3954 
    Details
    ISSN: 1089-7623
    Quelle: AIP Digital Archive
    Thema: Physik , Elektrotechnik, Elektronik, Nachrichtentechnik
    Notizen: Positive temperature coefficient (PTC) thermistor sensors have been used successfully for sensing and measurement of gas flow through a tube. Tuned detection technique using an ac signal is found to be a more efficient measuring circuit than the conventional dc Wheatstone bridge. Any particular sensor can be used to measure a wide range of flow rates using sensing heads of varying geometries. For a specific geometry, the plot of electrical voltage output against flow rate produces an "S" shaped curve which follows from the basic principles of heat transfer by both conduction and convection mechanisms. © 1999 American Institute of Physics.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1063/1.1150018
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  • 96
    Digitale Medien
    Digitale Medien
    Calibration of rectangular atomic force microscope cantilevers (1999)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 70 (1999), S. 3967-3969 
    Details
    ISSN: 1089-7623
    Quelle: AIP Digital Archive
    Thema: Physik , Elektrotechnik, Elektronik, Nachrichtentechnik
    Notizen: A method to determine the spring constant of a rectangular atomic force microscope cantilever is proposed that relies solely on the measurement of the resonant frequency and quality factor of the cantilever in fluid (typically air), and knowledge of its plan view dimensions. This method gives very good accuracy and improves upon the previous formulation by Sader et al. [Rev. Sci. Instrum. 66, 3789 (1995)] which, unlike the present method, requires knowledge of both the cantilever density and thickness. © 1999 American Institute of Physics.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1063/1.1150021
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  • 97
    Digitale Medien
    Digitale Medien
    Photoemission electron microscope for the study of magnetic materials (1999)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 70 (1999), S. 3973-3981 
    Details
    ISSN: 1089-7623
    Quelle: AIP Digital Archive
    Thema: Physik , Elektrotechnik, Elektronik, Nachrichtentechnik
    Notizen: The design of a high resolution photoemission electron microscope (PEEM) for the study of magnetic materials is described. PEEM is based on imaging the photoemitted (secondary) electrons from a sample irradiated by x rays. This microscope is permanently installed at the Advanced Light Source at a bending magnet that delivers linearly polarized, and left and right circularly polarized radiation in the soft x-ray range. The microscope can utilize several contrast mechanisms to study the surface and subsurface properties of materials. A wide range of contrast mechanisms can be utilized with this instrument to form topographical, elemental, chemical, magnetic circular and linear dichroism, and polarization contrast high resolution images. The electron optical properties of the microscope are described, and some first results are presented. © 1999 American Institute of Physics.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1063/1.1150023
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  • 98
    Digitale Medien
    Digitale Medien
    A small-angle neutron scattering cell for the study of supercritical fluids at elevated pressure and high temperature: A study of heavy water (1999)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 70 (1999), S. 4015-4019 
    Details
    ISSN: 1089-7623
    Quelle: AIP Digital Archive
    Thema: Physik , Elektrotechnik, Elektronik, Nachrichtentechnik
    Notizen: The main characteristics of a cell optimized for small-angle neutron scattering experiments on supercritical fluids are presented. The cell operates satisfactorily at pressures up to 300 bar at 400 °C and 750 bar at 90 °C. It has large apertures sealed by thick synthetic sapphire windows. The maximum forward scattering angle is 16° and the sample path length is 5.1 mm. It has been used to study scattering from supercritical heavy water close to its critical point at wave number transfers up to 0.34 Å−1. © 1999 American Institute of Physics.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1063/1.1150027
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  • 99
    Digitale Medien
    Digitale Medien
    Tomography of the fast electron bremsstrahlung emission during lower hybrid current drive on TORE SUPRA (1999)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 70 (1999), S. 3987-4007 
    Details
    ISSN: 1089-7623
    Quelle: AIP Digital Archive
    Thema: Physik , Elektrotechnik, Elektronik, Nachrichtentechnik
    Notizen: A new tomography dedicated to detailed studies of the fast electron bremsstrahlung emission in the hard x-ray (HXR) energy range between 20 and 200 keV during lower hybrid (LH) current drive experiments on the TORE SUPRA tokamak [Equipe TORE SUPRA, in Proceedings of the 15th Conference on Plasma Physics and Controlled Nuclear Fusion Research, Seville (International Atomic Energy Agency, Vienna, 1995), Vol. 1, AIEA-CN-60 / A1-5, p. 105] is presented. Radiation detection is performed by cadmium telluride semiconductors, which have most of the desirable features for a powerful diagnosing of magnetically confined hot plasmas—compact size, high x-ray stopping efficiency, fast timing characteristics, good energy resolution, no sensitivity to magnetic field, reasonable susceptibility to performance degradation from neutron/γ-induced damages. This instrument is made of two independent cameras viewing a poloidal cross-section of the plasma, with respectively 21 and 38 detectors. A coarse spectrometry—8 energy channels—is carried out for each chord, with an energy resolution of 20 keV. The spatial resolution in the core of the plasma is 4–5 cm, while the time sampling may be lowered down to of 2–4 ms. Powerful inversion techniques based on maximum entropy or regularization algorithms take full advantage of the large number of line-integrated measurements for very robust estimates of the local HXR profiles as a function of time and photon energy. A detailed account of main characteristics and performances of the diagnostic is reported, as well as preliminary results on LH current drive experiments. © 1999 American Institute of Physics.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1063/1.1150025
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  • 100
    Digitale Medien
    Digitale Medien
    A novel bulge-testing setup for rectangular free-standing thin films (1999)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 70 (1999), S. 4026-4031 
    Details
    ISSN: 1089-7623
    Quelle: AIP Digital Archive
    Thema: Physik , Elektrotechnik, Elektronik, Nachrichtentechnik
    Notizen: A newly designed bulge-testing apparatus for the mechanical testing of the tensile properties of free-standing thin films has been constructed and tested. With this instrument it is possible to measure the elastic modulus, tensile and compressive growth stress, and plain strain yield strength in thin films. The setup features a high strain resolution (4E-10), and a high stress resolution, e.g., 〉0.2 MPa for bulge heights larger than 10 μm. In our setup, thin films are stressed by a differential gas pressure across the film, while the deflection is measured by a scanning laser beam. The scanning laser beam measures the curvature of the bulge rather than the bulge height. This makes the setup insensitive to a possible initial nonflatness of the film. This also provides the possibility to measure the growth stress of films that were deposited under a compressive stress. We show the results of measurements of the plane strain modulus on thin tungsten films and on both flat and nonflat aluminum (alloy) film samples. © 1999 American Institute of Physics.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1063/1.1150029
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