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  • Articles  (51,370)
  • 1995-1999  (41,337)
  • 1960-1964  (6,996)
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  • Electrical Engineering, Measurement and Control Technology  (51,370)
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  • Articles  (51,370)
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  • 1
    Electronic Resource
    Electronic Resource
    Measurement of the thermoelectric power of very small samples at ambient and high pressures (1999)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 70 (1999), S. 3586-3589 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: There is currently much interest in the thermoelectric properties of materials. A method for measuring the thermoelectric power of small single-crystal or polycrystalline samples is described. For high-pressure measurements, the small samples are loaded into a diamond anvil cell and compressed. An infrared laser system is used to induce a temperature gradient in the sample. The thermoelectric power is measured with a pair of small thermocouples contacting the sample. Reported here is the thermoelectric power of Ni and the previously reported intermetallic compound CePd3 up to 10 GPa. Other standards measured by this method included: Bi, Yb, and CeSn3. © 1999 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1149964
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  • 2
    Electronic Resource
    Electronic Resource
    High resolution photothermal imaging of high frequency phenomena using a visible charge coupled device camera associated with a multichannel lock-in scheme (1999)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 70 (1999), S. 3603-3608 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: We have developed a technique using a photothermal microscope from which we can make a thermal image of an electronic component working at a "high frequency" using a charge coupled device (CCD) camera and a multichannel lock-in scheme. To do this, we have created an electronic "stroboscope": the frequency F of the thermal signal induced by a high frequency electrical excitation and the frequency of the light F+f that illuminates the device are next to each other; the signal reflected at the surface of the device whose amplitude is proportional to the variation of reflectivity and hence to the variation of temperature and whose frequency is the blinking one f is analyzed by a visible CCD camera. Amplitude and phase images of the high frequency thermal phenomenon can then be made. Moreover, this technique presents a great advantage: the spatial resolution is better than 1 μm. The amplitude and phase images presented show, with a very good spatial resolution, Joule and Peltier heating of a polycrystalline silicon 2.5 kΩ resistor across which a sinusoidal current is forced. © 1999 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1149966
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  • 3
    Electronic Resource
    Electronic Resource
    A high-field/high-frequency heterodyne induction-mode electron paramagnetic resonance spectrometer operating at 360 GHz (1999)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 70 (1999), S. 3681-3683 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: We present design details of and first measurements with a novel continuous wave (cw) high-field/high-frequency electron paramagnetic resonance spectrometer operating at a microwave frequency of 360 GHz and a magnetic field of up to 14 T. The spectrometer design incorporates a heterodyne mixer detection scheme with a quasi-optical transmission line and a bimodal induction mode Fabry–Perot cavity. First cw experiments on polycrystalline 1,1-diphenyl-2-picryl-hydrazyl and bisdiphenylene-β-phenylallyl benzolate in polystyrene at room temperature and 4-hydroxy-2,2,6,6-tetramethylpiperidine-1-oxyl in frozen solution at 190 K demonstrate the high Zeeman resolution achievable and allow an estimate of the present detection sensitivity of 4×109 spins/G at a detection bandwidth of 1 Hz. © 1999 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1149977
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  • 4
    Electronic Resource
    Electronic Resource
    A highly sensitive quartz-crystal microbalance for sputtering investigations in slow ion–surface collisions (1999)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 70 (1999), S. 3696-3700 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: A quartz-crystal microbalance technique for measuring total sputter yields in ion–surface collisions is described. The electronic circuit to drive the quartz crystal ensures low noise and high frequency stability. By measuring total sputter yields for impact of singly charged ions on LiF target films a sensitivity limit of 0.5% of a monolayer per minute could be achieved. © 1999 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1149979
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  • 5
    Electronic Resource
    Electronic Resource
    Multipurpose high vacuum laser ablation/thin film deposition system (1999)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 70 (1999), S. 3701-3706 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: An instrumental system is described that combines an apparatus for pulsed laser deposition (PLD) with a vacuum "suitcase" for transport of air-sensitive compounds. Laser ablation, plume diagnostics, and thin-film deposition are readily accomplished through a flexible design. The PLD apparatus consists of two cubes coupled via a bellows assembly and whose distance is easily changed pneumatically. For both the PLD apparatus and the vacuum suitcase, compact-design considerations have been implemented. Consequently, the footprint of the PLD apparatus is relatively small, and the vacuum suitcase can be transported easily between sites. © 1999 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1149980
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  • 6
    Electronic Resource
    Electronic Resource
    Contour temperature programmed desorption for monitoring multiple chemical reaction products (1999)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 70 (1999), S. 3719-3722 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: A simple method for obtaining a comprehensive overview of major compounds desorbing from the surface during temperature programmed desorption (TPD) experiments is outlined. Standard commercially available equipment is used to perform the experiment. The method is particularly valuable when high molecular mass compounds are being studied. The acquisition of contour temperature programmed desorption (CTPD) spectra, sampling 50-dalton mass ranges at a time in the thermal desorption experiments, is described and demonstrated for the interaction of benzotriazole adsorbed on a Ni(111) surface. Conventional two-dimensional TPD spectra can be extracted from the CTPD by taking vertical slices of the contour. © 1999 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1149983
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  • 7
    Electronic Resource
    Electronic Resource
    Introduction to a kinetics-sensitive double-step voltcoulometry (1999)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 70 (1999), S. 3723-3734 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: As an alternative to the numerous state-of-the-art versions of voltammetry, a kinetics-sensitive double-step voltcoulometry is introduced. The transient current flowing in response to a potential step across the electrochemical cell is integrated and simultaneously processed by a deliberately selected time-domain "cascade" filter, while scanning the applied potential. In contrast to the widely used sampling scheme of sampling the transient current just before and in the end of the excitation pulse, three values of the transient charge are sampled in the interval between subsequent excitation pulses. Each measuring period is preceded by a single measurement of the steady-state current with the excitation pulse being switched off. The latter measurement makes it possible to actively compensate the parasitic charge across the feedback capacitor of the integrator, due to the steady-state current, while storing the steady-state current data. The goal of introducing the third sampling event resides in discriminating the kinetics of the transient charge via the parameter β that enters the time dependence of the transient charge Δq∝tβ. In general, our filtering scheme is capable of eliminating both any constant or linear components in the transient charge (β=0, 1). Moreover, any superlinear transient charge (β〉1) is detected as a peak of the Δq versus potential plot with its sign being opposite to that one of a sublinear redox reaction (0〈β〈1). This enhanced performance of our double-step voltcoulometry is documented by a series of experiments on aqueous solutions of ascorbic acid using a carbon fiber microelectrode as the working electrode. Finally, how to assess the degree of reversibility of the redox reaction and deduce the time constant RC of the double-layer charging current is shown. © 1999 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1149984
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  • 8
    Electronic Resource
    Electronic Resource
    Microwave-induced acoustic imaging of biological tissues (1999)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 70 (1999), S. 3744-3748 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: We present tomographic imaging of biological tissues by use of microwave-induced acoustic signal. It was demonstrated that the acoustic signal was proportional to the intensity of the incident microwave and was related to the absorption property of microwave in the medium. Pulsed microwave radiation was used to illuminate the samples. Absorbed microwave energy caused thermoelastic expansion that radiated acoustic waves. A focused ultrasonic transducer detected the time-resolved acoustic signals. Each acoustic signal was converted into a one-dimensional image. A linear scanning of the ultrasonic transducer yielded multiple one-dimensional images, which formed a two-dimensional image. The imaging contrast is based on the difference in the dielectric constants among biological tissues. Because of the large contrast in microwave absorption among different tissue types, microwave-induced acoustic tomography could potentially provide a new modality for detecting early-stage cancers. © 1999 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1149986
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  • 9
    Electronic Resource
    Electronic Resource
    Locking the cavity of a pulsed periodically poled lithium niobate optical parametric oscillator to the wavelength of a continuous-wave injection seeder by an "intensity-dip" method (1999)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 70 (1999), S. 3203-3213 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: Injection seeding by a single-mode continuous-wave (cw) laser provides a convenient way to achieve narrowband tunable operation of a laser with a broad spectral gain profile, or of an optical parametric oscillator (OPO). Continuous single-mode tunability of the laser or OPO output usually requires the length of the optical cavity to be controlled as the injection-seeding wavelength is scanned. We report a novel variant on established methods of locking the optical cavity length to the seed wavelength. Our approach takes advantage of the resonance properties of an optical cavity. When the cavity is in resonance with the cw seed radiation, the total intensity of that radiation reflected off the cavity displays a pronounced dip; this intensity dip can be used as a locking signal to reset the cavity length piezoelectrically during each interval between the pump pulses that excite the laser or OPO. Our active cavity-locking scheme is realized in the case of a ring-cavity OPO, incorporating periodically poled lithium niobate (PPLN), pumped at 1.064 μm by a single-mode pulsed Nd:yttrium–aluminum–garnet laser and injection-seeded at its signal wavelength by a 1.55 μm single-mode tunable diode laser. The coherent infrared output of this injection-seeded PPLN OPO is shown to be continuously tunable, with an optical bandwidth of ∼130 MHz (0.0045 cm−1) and excellent spatial beam quality. © 1999 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1149895
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  • 10
    Electronic Resource
    Electronic Resource
    Transient temperature measurements in an ideal gas by laser-induced Rayleigh light scattering (1999)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 70 (1999), S. 3222-3226 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: A laser-induced Rayleigh light-scattering (RLS) system was assembled and used to noninvasively measure the transient molecular number density in an ideal gas. This information was used to find the transient gas temperature when operating at known pressure. The laser was a 4 W argon ion operating on all lines at a total power of about 2.5 W. The theoretically predicted photon arrival rate at the photomultiplier tube detector was calculated and compared well with the observed photon rates. These rates were high enough that sampling could be averaged over a 1 s period with theoretical uncertainty due to electronic shot noise below 0.1%, and below 2% for a 0.001 s averaging time. A propagated error analysis showed uncertainty in the transient temperature due to all sources was 2–4 K. The RLS system was used to record transient air temperature at several locations above a flat plate during heating from room temperature to 475 K. Results showed buoyancy-induced fluctuations of about 3 Hz, and instabilities in temperature in addition to the overall temperature rise due to plate heating. Excellent transient temperature records were obtained, substantiating the predicted 2–4 K uncertainty. © 1999 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1149896
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  • 11
    Electronic Resource
    Electronic Resource
    Six-circle diffractometer for surface diffraction using an in-vacuum x-ray detector (1999)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 70 (1999), S. 3239-3243 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: We report on the design of a diffractometer, which offers improved capabilities for x-ray experiments in ultrahigh vacuum. Its main features are (i) the possibility to follow the evolution of diffraction spots in situ during adsorption or film deposition; (ii) the measurement of reflections at high exit angles, i.e., large perpendicular momentum transfer. This goal is achieved by placing a movable x-ray detector inside the vacuum chamber. (iii) Other surface analysis equipment, e.g., a low-energy electron diffraction or an electron energy analyzer can be moved in front of the sample and operated simultaneously with x-ray diffraction. (iv) A load lock system—currently in preparation—will allow the quick exchange of samples without breaking system vacuum. In addition, a new design of the chi circle used for sample alignment provides a compact, space-saving design of the diffractometer. © 1999 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1149899
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  • 12
    Electronic Resource
    Electronic Resource
    Multiply charged cluster ion crossed-beam apparatus: Multi-ionization of clusters by ion impact (1999)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 70 (1999), S. 3244-3253 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: An experimental setup is described, which is used to multi-ionize neutral clusters and to study their stability and the importance of different decay processes. Clusters are ionized in collisions with slow multiply charged ions (projectile charge z ranging from 1 to 30, kinetic energies ranging from 1 to 20 keV/charge). Both ion and cluster beamlines, as well as the characteristics of the analysis and detection systems, are described. Collisions with highly charged ions such as Ar8+ or Xe30+ turn out to be efficient tools in preparing clusters in high charge states without increasing significantly their internal temperature. Measurements performed in coincidence with the number of electrons stabilized by the projectile ion after the collision allowed us to control the charge and the excitation energy of the ionized system. The efficiency of the method is demonstrated for sodium clusters and C60 molecules. © 1999 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1149900
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  • 13
    Electronic Resource
    Electronic Resource
    A crossed molecular beam apparatus using high-resolution ion imaging (1999)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 70 (1999), S. 3265-3270 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: A new crossed molecular beam apparatus with a high-resolution ion imaging detector is described. Two pulsed supersonic molecular beams are crossed at right angles in a vacuum of 10−7 Torr. The collision region is irradiated with a tunable laser pulse that ionizes the scattered particles state selectively. The generated ions are accelerated by stacked electrodes in a two-dimensional (2D) space focusing mode that increases the velocity resolution of the apparatus. A cylindrical hexapole deflector is placed in the middle of the time-of-flight mass spectrometer to compensate the center-of-mass velocity of the ions and to direct them to the center of the 2D imaging detector. Real-time image processing of the charge coupled device camera signal eliminates blurring of the image detector. The performance of the apparatus was examined by observing the inelastic scattering of NO+Ar at a collision energy of 66 meV. The observed multiple rainbow peaks clearly demonstrate the high performance of the apparatus. © 1999 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1149902
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  • 14
    Electronic Resource
    Electronic Resource
    Characterization of high charge electron beams induced by excimer laser irradiation (1999)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 70 (1999), S. 3277-3281 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: This work reports on electron beam characteristics obtained from a Cu photocathode utilizing an UV excimer laser of 222 nm for the first time. The values of the current, emittance, and brightness of the electron beams generated are reported. A suitable slit–slit emittance meter was developed to assess the electron beam emittance. This instrument allowed us to determine the electron beam phase-space areas by slicing the beam in small beamlets and measuring the beamlet direction distributions. Small Faraday cups placed after the slits were utilized to this reason. The laser beam was focused in a 4 mm2 spot and the maximum energy laser was established to 0.5 mJ. The highest current was 410 mA and the corresponding normalized emittance value was 10 π mm mrad corresponding to 80% of the total points. From these data the beam quality, expressed as normalized beam brightness, resulted in 4.1×109 A[π m rad]−2 and the quantum efficiency was 4.6×10−5. By increasing the KrCl laser spot and its energy a very charge electron beam was extracted of 16.4 A. © 1999 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1149904
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  • 15
    Electronic Resource
    Electronic Resource
    Fast beam photofragment apparatus for studies of electronic and nuclear dynamics (1999)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 70 (1999), S. 3289-3298 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: A new fast beam photofragment apparatus for studies of electronic and nuclear dynamics is described. The experimental setup involves a chopped ion beam crossed at 90° by a pulsed laser beam. Photofragments are extracted parallel to the ion beam direction and imaged on a multisphere plate (MSP) detector. The time of flight of a photofragment from the interaction point to the MSP detector is determined by a coincidence technique. The setup allows determination of the photofragment energy and the direction of emission for each event of photofragmentation. In photoelectron spectrometry the energy resolution is tunable down to the meV region. For testing, the apparatus has been applied to photodetachment of Li−(1S) at 1064 nm. © 1999 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1149906
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  • 16
    Electronic Resource
    Electronic Resource
    Focusing characteristics of intense beam solenoid lens (1999)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 70 (1999), S. 3303-3307 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: In this article, by solving the nonlinear envelope equation of the intense beam in the cylindrical coordinate system, we have obtained the varying relations of the beam radius and the beam divergent angle with the paramedics (the magnetic induction strength in solenoid lens, the characteristic quantity of beam intensity, the beam emittance, the initial beam radius, and initial beam divergent angle). By theoretical analysis for the relations, we have obtained the beam peak radius and beam peak position in solenoid lens, the beam waist radius and beam waist position in the case of perfect focusing. In the ideal focusing condition, the radius of intense beam solenoid lens should not be less than the beam peak radius; the length of the solenoid lens must not be less than the beam peak position; and in order to gain optimum focusing, an optimal length should be selected; the magnetic induction strength must not be less than the threshold for getting a focusing beam through solenoid lens, and its optimum value should be selected so as to obtain the minimum value of beam divergent angle at the exit port for getting an perfect focusing output beam. The conclusions in this article have some guiding significance for the design and operation of the intense beam solenoid magnetic lens.© 1999 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1149908
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  • 17
    Electronic Resource
    Electronic Resource
    Toroidal crystal spectrometer for time-resolved x-ray absorption diagnostic in dense plasmas (1999)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 70 (1999), S. 3314-3318 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: A toroidal crystal spectrometer was designed with the purpose of measuring the aluminum K-absorption edge shift, in the wavelength range around 7.9 Å, in strongly compressed matter. The expected shift is about 100 mÅ (∼20 eV). The x rays reflected from the crystal are focused onto a streak camera slit of 16 mm high and 100 μm width, to obtain a time-resolved spectrum. High resolution and dispersion of about 1–16 Å/mm on the detection window are obtained. A crystal with a toroidal surface is used to enhance the focusing power in the spatial dimension as in the spectral one. Numerical simulations are performed by means of one- and two-dimensional codes for the determination of the crystal characteristics like the dimension and the curvature radius with respect to the geometric constraints. Some experimental results are presented concerning the obtained spectra. © 1999 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1149910
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  • 18
    Electronic Resource
    Electronic Resource
    Vacuum arc plasma transport through a magnetic duct with a biased electrode at the outer wall (1999)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 70 (1999), S. 3329-3331 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: Metal plasma formed by a vacuum arc plasma source can be passed through a toroidal-section magnetic duct for the filtering of macroparticles from the plasma stream. In order to maximize the plasma transport efficiency of the filter the duct wall should be biased, typically to a positive voltage of about 10–20 V. In some cases it is not convenient to bias the duct, for example if the duct wall is part of the grounded vacuum system. However, a positively biased electrode inserted into the duct along its outer major circumference can serve a similar purpose. In this article, we describe our results confirming and quantifying this effect. We also show the parametric dependence of the duct transport on the experimental variables. © 1999 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1149913
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  • 19
    Electronic Resource
    Electronic Resource
    Ion beam mass spectrometer for compositional analysis of plasma assisted surface processes in the pressure range of 1–50 mbar (1999)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 70 (1999), S. 3324-3328 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: Ion beam mass spectrometry (IBMS) has been developed for in situ, real-time monitoring of the ion composition of a plasma in the vicinity of the substrate surface up to a pressure of 50 mbar. Our system was designed for the specific case of diamond deposition in a microwave plasma enhanced chemical vapor deposition chamber, however, it can be adapted to other applications as well, without significant change in the process chamber. Ion beam mass spectrometer is a quadrupole mass spectrometer (QMS) based plasma sampling system installed into a separately pumped small analysis chamber. The interface between the two chambers is the top part of the IBMS, specially designed to serve as the sample holder of the reactor chamber (sample heating and biasing is possible). A technique containing wet etching and laser treatment has been developed to form a sufficiently small orifice in various substrates. This orifice samples the particles arriving onto the surface from the plasma but is small enough to maintain the flow effusive into, and an appropriate pressure in the analysis chamber. Directly behind the orifice specially designed ion-optics direct the ions coming from the process chamber into the QMS for mass and energy separation. Since the total flow from the reactor chamber is low, the mean free path in the analysis chamber is sufficiently longer than the distance from the orifice to the QMS, therefore, ions do not collide, thus they do not react after sampling. As a consequence, nonstable species are also detected. The carefully designed ion-optics ensure that a high ion current reaches the QMS. In this article, it is shown that the intensity ratios in the spectra correspond to the concentration ratios of the ions arriving to the substrate surface. The QMS is also equipped with a conventional cross electron beam ion source allowing measurements of neutral species by conventional ionization. © 1999 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1149912
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  • 20
    Electronic Resource
    Electronic Resource
    Stroboscopic x-ray topography in crystals under 10-μm-surface acoustic wave excitation (1999)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 70 (1999), S. 3341-3345 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: High-frequency stroboscopic x-ray topography is developed with the goal to visualize surface acoustic wave propagation. For this purpose the resonant frequencies of LiNbO3-based surface acoustic wave devices (290 and 355 MHz) are synchronized with the frequency of x-ray flashes (5.68 MHz) delivered by the European Synchrotron Radiation Facility (ESRF, Grenoble). X-ray topographs, taken in such a manner, revealed periodic contrast caused by a "frozen" acoustic deformation field. This technique allows for visualization of individual wavefronts of traveling acoustic waves having a wavelength in a 10 μm range. X-ray stroboscopic topographs showed a weak wavefront distortion due to the scattering of acoustic waves on linear dislocations. Secondary spherical waves were observed as a result of the strong acoustic wave interaction with submicron size density perturbations. © 1999 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1149916
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  • 21
    Electronic Resource
    Electronic Resource
    A unique optical arrangement for obtaining spectrally resolved confocal images (1999)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 70 (1999), S. 3351-3354 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: The design for a confocal beam-scanning microscope with a unique optical configuration for the rapid acquisition of spectrally resolved images is presented. The novel aspect of the optical configuration is the location of the detection device, which is placed in an intermediate position between fully descanned detection and nondescanned detection (direct projection). This placement allows for the practical implementation of spectrally resolved confocal imaging. The device is demonstrated by the spectral resolution of a sample of fluorescently labeled microbeads. © 1999 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1149918
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    The novel surface science instrument: Double reflection electron emission microscope (1999)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 70 (1999), S. 3346-3350 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: A universal UHV instrument, the double reflection electron emission microscope (DREEM), for surface imaging, diffraction, and local (1 μm resolution) measurements is presented. DREEM consists of three fully electrostatic lens systems: electron gun column, immersion objective lens, and imaging column. The novel illumination system incorporates an electron microreflector in the back focal plane of the objective, where the perpendicular optical axes of the electron gun and imaging column cross. The electron microreflector consists of the tip of a (001)-oriented single-crystalline W wire with a face of area 200 μm2. The primary electrons of energy from 1 to 6 keV elastically reflect from the W tip surface and are decelerated between the objective and grounded sample to the desired impact energy from 0 eV to 5 keV. Numerous contrast mechanisms are expected for image formation with DREEM including topographic, magnetic, chemical (Auger, core level), phase shift, and work function. The instrument is capable of operating in low energy electron diffraction, mirror electron microscopy, low energy electron emission microscope, and photoelectron emission microscope modes. The first results obtained with the DREEM are presented. © 1999 American Institute of Physics.
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    URL: http://dx.doi.org/10.1063/1.1149917
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    A variable cryogenic temperature near-field scanning optical microscope (1999)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 70 (1999), S. 3355-3361 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: We describe a novel variable (cryogenic) temperature near-field scanning optical microscope (VT-NSOM) designed specifically for submicron imaging of materials and devices over a temperature range of 12–300 K. In high vacuum, we cool only the sample stage of the compact NSOM, thereby maintaining a large scan area (35 μm×35 μm) at low temperatures and enabling rapid (∼30 min) temperature changes. With incorporation into an external conventional optical microscope, the VT-NSOM is capable of imaging a single submicron feature over the entire temperature range. We demonstrate the performance of the instrument by examining the photoresponse of threading dislocation defects in relaxed GeSi films. © 1999 American Institute of Physics.
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    URL: http://dx.doi.org/10.1063/1.1149919
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    Low-temperature atomic force microscope using piezoresistive cantilevers (1999)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 70 (1999), S. 3369-3372 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: This article describes the design of an easy-to-operate low-temperature atomic force microscope (AFM) that incorporates piezoresistive cantilevers. The instrument is easier to build and to operate at cryogenic temperatures than AFMs based on laser deflection schemes or interferometers because no mechanical adjustments of the instrument are necessary after a change of temperature. The effects of thermal expansion on the AFM's tip-to-sample distance are minimized by the use of a double tube scanner assembly. The design includes a simple mechanism that locks the sample holder in place as the temperature is lowered. This AFM is compact and rigid, enabling it to be used in a conventional cryogenic liquid-storage Dewar. All of the materials used in the construction of the AFM are ultra-high-vacuum compatible.
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    URL: http://dx.doi.org/10.1063/1.1149945
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    Microwave-frequency alternating current scanning tunneling microscopy by difference frequency detection: Atomic resolution imaging on graphite (1999)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 70 (1999), S. 3377-3380 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: We present a detailed description of an experimental setup for alternating current scanning tunneling microscopy, in which two slightly detuned high frequency signals are mixed at the tunneling junction and the resulting difference frequency signal is amplified using conventional scanning tunneling microscope electronics. This signal is used to control the distance between the microscope tip and the sample. With graphite as a model surface atomic resolution images have been obtained. It is demonstrated that the origin of the generated signal on graphite is the nonlinearity of the static current–voltage characteristics. © 1999 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1149922
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    A reproducible method to fabricate atomically sharp tips for scanning tunneling microscopy (1999)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 70 (1999), S. 3373-3376 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: The electrochemical etching method by Ibe et al. [J. Vac. Sci. Technol. A 8, 3570 (1990)] to fabricate sharp tips for scanning tunneling microscopy was modified by shortening the cutoff time of the etching current after the material wire drops off at the air-electrolyte interface. The tip radius measured by field ion microscopy was successfully reduced to 8 nm when the cutoff time was shortened to 50 ns. The dependence of the field-emitting electron current from the sharpest tips was close to one expected from the Fowler–Nordheim formula with a reasonable value for the emitting area of the tip. © 1999 American Institute of Physics.
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    URL: http://dx.doi.org/10.1063/1.1149921
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    Real-time, interferometrically measuring atomic force microscope for direct calibration of standards (1999)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 70 (1999), S. 3362-3368 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: An atomic force microscope with a high-resolution three-axis laser interferometer for real-time correction of distorted topographic images has been constructed and investigated. With this apparatus, standard samples for a scanning probe microscope can be directly calibrated on the basis of stabilized wavelength of He–Ne lasers. The scanner includes a three-sided mirror block as a mobile target mirror for the interferometer, which realizes a rectangular coordinate system. The position coordinates of the sample is independently and simultaneously acquired with high-resolution (0.04 nm) X/Y/Z interferometer units and fed back for XY servo scanning and height image construction. The probe is placed on the sample surface at the intersection of the three optical axes of the interferometer with good reproducibility, so that the Abbe error caused by the rotation of the scanner is minimized. Image distortion in the XY plane and vertical overshoot/undershoot due to nonlinear motion of piezo devices, hysteresis, and creep are eliminated. The optical properties of the interferometers, mechanical characteristics of the scanner, and system performances in dimensional measurements for calibration standards are demonstrated. © 1999 American Institute of Physics.
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    URL: http://dx.doi.org/10.1063/1.1149920
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    A novel resonant beam technique to determine the elastic moduli in dependence on orientation and temperature up to 2000 °C (1999)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 70 (1999), S. 3052-3058 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: A new equipment was developed to determine the elastic moduli from the resonance frequencies of the flexural vibrations of a beam up to temperatures of 2000 °C. The elastic moduli are calculated by minimizing the difference of the experimental versus the theoretical resonance frequencies. The theoretical frequencies are obtained by numerically solving Timoshenko's equation, which takes into account the influence of the shear deformation and the rotatory inertia. From the fundamental frequency and the higher modes of vibration, one Young's modulus and two shear moduli (e.g., E11, G12, and G13) are obtained, the latter two coincide for an elastically isotropic material. With the additional effort of cutting out specimens in specific directions, the complete elastic tensor of anisotropic materials can be measured at high temperatures. The limits and the precision of the method are discussed. © 1999 American Institute of Physics.
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    URL: http://dx.doi.org/10.1063/1.1149867
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    Nanometer-displacement detection of optically trapped metallic particles based on critical angle method for small force detection (1999)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 70 (1999), S. 3068-3073 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: We have developed a method of measuring the displacement of optically trapped metallic particles (10 μm in diameter) in water with nanometer resolution to detect small forces. Metallic particles were optically trapped in two dimensions by focusing a laser beam below the particle using an objective lens with a numerical aperture of 0.9. Displacement of a trapped metallic particle was detected using the light reflected from the particle based on the critical angle method. The lateral spring constant was estimated from the equipartition theorem to be on the order of 10−6 N/m and found to increase as the incident laser power increased. Consequently, a trapped metallic particle can be used to detect small forces (10−13 N). © 1999 American Institute of Physics.
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    URL: http://dx.doi.org/10.1063/1.1149868
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    Laser power build-up cavity for high-resolution laser spectroscopy (1999)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 70 (1999), S. 3515-3518 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: The design, construction, and operation of an optical build-up cavity (BUC) designed primarily for use in molecular beam laser spectroscopy where signal is proportional to laser power, is presented. The design is such that the cavity has no internal adjustment controls, needing only alignment with respect to the laser and molecular beams. When used with a single-mode titanium:sapphire laser, a circulating cw power of 900 W was achieved. The BUC increased the signal to noise of the experiment by a factor of 390 relative to a single crossing of laser and molecular beam without degrading resolution. Performance of the BUC is limited by heating of its mirrors by the high power densities incident upon them (∼3 MW cm−2). © 1999 American Institute of Physics.
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    URL: http://dx.doi.org/10.1063/1.1149952
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    Design and fabrication of a simple pneumatic loading attachment for diamond anvil cells (1999)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 70 (1999), S. 3074-3076 
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    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: A simple pneumatic pressure attachment has been designed and fabricated for Mao–Bell and National Bureau of Standard type diamond anvil cells (DACs). The assembly can be fitted to the lever arm of the DAC for applying pressure on the diamonds and the pressure at the sample site has been calibrated against the gas dial using the equation of state of silver loaded in the DAC. © 1999 American Institute of Physics.
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    URL: http://dx.doi.org/10.1063/1.1149869
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    Rotating analyzer–fixed analyzer ellipsometer based on null type ellipsometer (1999)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 70 (1999), S. 3077-3082 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: The theory and design of an inexpensive rotating analyzer unit is presented, which allows a conventional null type ellipsometer to work as rotating analyzer–fixed analyzer automatic ellipsometer, without sacrificing the possibility to work in null mode. The mode switching is performed simply by adding or removing the rotating analyzer from its holder. It is shown that the rotating analyzer phase shift in rotating analyzer–fixed analyzer mode can be run-time determined from the measured Fourier coefficients. This avoids any need of recalibration procedure after mode switching and makes unnecessary plane of incidence synchronization, which further simplifies the needed hardware and reduces the errors connected with the phase shift instability of the output signal. The run-time phase shift calibration procedure and subsequent ellipsometric angles determination do not involve normalization of the output signal Fourier coefficients to the zeroth harmonic, eliminating in this way the influence of the dc component time drift. © 1999 American Institute of Physics.
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    URL: http://dx.doi.org/10.1063/1.1149870
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    New high temperature furnace for structure refinement by powder diffraction in controlled atmospheres using synchrotron radiation (1999)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 70 (1999), S. 3554-3561 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: A low thermal gradient furnace design is described which utilizes Debye–Scherrer geometry for performing high temperature x-ray powder diffraction with synchrotron radiation at medium and high energies (35–100 keV). The furnace has a maximum operating temperature of 1800 K with a variety of atmospheres including oxidizing, inert, and reducing. The capability for sample rotation, to ensure powder averaging, has been built into the design without compromising thermal stability or atmosphere control. The ability to perform high-resolution Rietveld refinement on data obtained at high temperatures has been demonstrated, and data collected on standard Al2O3 powder is presented. Time-resolved data on the orthorhombic to rhombohedral solid state phase transformation of SrCO3 is demonstrated using image plates. Rietveld refinable spectra, collected in as little as 8 s, opens the possibility of performing time-resolved structural refinements of phase transformations. © 1999 American Institute of Physics.
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    URL: http://dx.doi.org/10.1063/1.1149948
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    Unipolar arc simulation device (1999)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 70 (1999), S. 3583-3585 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: We describe a simple laboratory device for establishing a vacuum arc plasma discharge that can serve to simulate a unipolar arc. The technique makes use of a triggered vacuum arc plasma gun to generate a plasma plume that in turn causes breakdown of a secondary discharge. The device is in fact a secondary vacuum arc discharge that is triggered by a primary vacuum arc discharge, with some of the features of the secondary plasma discharge having similarities with a unipolar arc configuration. Here we describe the experimental setup and outline how the device can be used for some areas of unipolar arc materials research. © 1999 American Institute of Physics.
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    URL: http://dx.doi.org/10.1063/1.1149963
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    Investigation of a microwave differential cavity resonator device for the measurement of humidity in gases (1999)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 70 (1999), S. 3590-3594 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: A resonant cavity based microwave differential device has been developed as a sensor for the measurement of small quantities of water vapor in gases. The presence of a contaminant is assessed by induced variations in the relative permittivity due to a shift in the resonant frequency of the measuring resonator. The measured output signal is related to the difference in the reflection coefficients of the measuring resonator and the reference one. A simple modeling approach of the system shows the proportionality between the difference of the reflection coefficients of the cavities and the variation in the dielectric constant. The evaluation of the minimum detectable change in the permittivity is possible using the Clausius–Mossotti equation for a binary gas mixture at a given concentration and pressure. The detection threshold is then determined by taking into account the signal-to-noise ratio of the differential setup. The estimation of the limit of detection for some practical moisture contaminated gases yields values in the low ppm level at T=293 K and atmospheric pressure. Experimental data suggest a detection threshold of 6 ppm for moisture. © 1999 American Institute of Physics.
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    URL: http://dx.doi.org/10.1063/1.1149995
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    An inductively coupled, doubly tuned resonator for in vivo nuclear magnetic resonance spectroscopy (1999)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 70 (1999), S. 3454-3456 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: We present a coil designed for in vivo 31P and 1H nuclear magnetic resonance spectroscopy which consists of a doubly tuned resonator inductively coupled to separate 1H and 31P feed coils. The advantages of the resonator include the ability to 1H shim over the same volume from which 31P spectra are extracted by using a single sample coil, elimination of coupling problems between separate 1H and 31P coils, ease of design and tuning over conventional double-tuned coils, and reduced match/tune sensitivity to coil loading, which is important in in vivo applications. We have used this coil to collect phosphorus spectra from the in situ heart of the western painted turtle (Chrysemys picta bellii) at 2 T. The total heart volume was less than 1 mL and acquisition time was just under 10 min. © 1999 American Institute of Physics.
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    URL: http://dx.doi.org/10.1063/1.1149936
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    Suspension last stages for the mirrors of the Virgo interferometric gravitational wave antenna (1999)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 70 (1999), S. 3463-3472 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: We describe the design of the last stage suspension for the mirrors of the Virgo gravitational wave detector and, in particular, its key mechanical elements: the marionette and the reaction mass. Since the whole suspension system is an electromechanical device, we present both its mechanical and electromagnetic components. The main features of the fully assembled prototype and those worked out for the Virgo final design are discussed. © 1999 American Institute of Physics.
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    URL: http://dx.doi.org/10.1063/1.1149938
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    Streamer discharge reactor for water treatment by pulsed power (1999)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 70 (1999), S. 3457-3462 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: The streamer discharges are effectively used for biological and chemical cleaning of air and water. Uniform streamer discharges were obtained in water at pulsed electric loading. The volume of these discharges exceeds 400 cm3 and the energy delivered to the discharge reached 40–400 J depending on the applied voltage. The reliable and durable reactor for water treatment by pulsed streamer discharges is designed and tested. High voltage pulse amplitude applied to the reactor requires improved electric insulation to prevent flashover along the reactor surface both in water and air. High mechanical stress due to high discharge current adds the requirements to the mechanical durability of the system. A small-size reactor with the volume of approximately 1 l withstands successfully both high electrical and mechanical stresses. The reactor is designed for research purposes, however it can be upgraded to use in a high repetition-rate regime necessary for industrial applications. © 1999 American Institute of Physics.
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    URL: http://dx.doi.org/10.1063/1.1149937
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    A novel capacitive wave form transformer (1999)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 70 (1999), S. 3479-3482 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: This article describes a new method of wave form transformation through the use of a nonlinear capacitor. Two specific examples, the transformation of a sinusoidal wave form to a triangular wave form and vice versa are discussed in detail. A method of obtaining this nonlinear capacitor, by having a suitable doping profile in a metal–oxide–semiconductor capacitor is also described. © 1999 American Institute of Physics.
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    URL: http://dx.doi.org/10.1063/1.1149940
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    Low-noise, low drift, high precision linear bipolar (±10 V) voltage supply/reference for cryogenic front-end apparatus (1999)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 70 (1999), S. 3473-3478 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: A very simple linear bipolar (±10 V) voltage supply/reference (VS/R) featuring very low noise has been implemented. The noise is about 1 μVpp in a 0.1–10 Hz bandwidth, becoming, for the −10 V supply only, 1.3 μVpp at 1.5 A. The VS/R is based on commercial devices and has been designed to face the stringent requirement of very low drift systems. It features very good line regulation, less than 10 mV over 10 V at 1.5 A supply current, and very low drift, between 3 and 8 ppm/°C; it also shows large power supply rejection ratio (PSRR), 〉120 dB. The VS/R presented includes also safety circuits, to protect itself and the electronic equipment to be supplied in an actual experimental condition. It is protected against inversion of polarity and against under and over voltage at its inputs, and has a foldback current limiting circuit which shuts down the whole system if the current absorption lasts for some time. These protecting circuits acts on both outputs (±10 V), to maintain always the symmetry. From an analysis made on the data extracted from the measured noise spectra, it was possible to measure the dynamic output impedance, found mainly inductive, with a value of the order of 1 mH. The dc PSRR has been improved by about 20 dB with respect to the performances of the devices used, thanks to a very simple circuit solution. © 1999 American Institute of Physics.
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    A high precision method for measuring very small capacitance changes (1999)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 70 (1999), S. 3483-3487 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: A novel method for measuring very small capacitance changes based on capacitance-to-phase angle conversion is introduced in this article. This new method is the improved or linearized version of the nonlinear capacitance-to-phase angle conversion method. The main features of this scheme are the very good linearity, extremely high stray immunity and a very high resolution. The experimental results of the prototype version of this scheme have also been reported. By using this prototype and a simple capacitive transducer, a minimum detectable distance of about 16 nm can be achieved. This means that a capacitance change of about 0.7 fF (0.7×10−15 F) in a capacitance of 22 pF can be resolved, so the minimum resolvable relative capacitance is about 32 ppm. By the theory it can be seen that the minimum resolvable relative capacitance of 2 ppm could be achieved by this method. © 1999 American Institute of Physics.
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    High-precision hydraulic Stewart platform (1999)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 70 (1999), S. 3488-3494 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: We present a novel design for a Stewart platform (or hexapod), an apparatus which performs positioning tasks with high accuracy. The platform, which is supported by six hydraulic telescopic struts, provides six degrees of freedom with 1 μm resolution. Rotations about user defined pivot points can be specified for any axis of rotation with microradian accuracy. Motion of the platform is performed by changing the strut lengths. Servo systems set and maintain the length of the struts to high precision using proportional hydraulic valves and incremental encoders. The combination of hydraulic actuators and a design which is optimized in terms of mechanical stiffness enables the platform to manipulate loads of up to 20 kN. Sophisticated software allows direct six–axis positioning including true path control. Our platform is an ideal support structure for a large variety of scientific instruments that require a stable alignment base with high-precision motion. © 1999 American Institute of Physics.
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    URL: http://dx.doi.org/10.1063/1.1149942
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    A method for the growth and cooling of strain-free single crystals of cryogenic solids (1999)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 70 (1999), S. 3495-3496 
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    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: A technique has been developed for growing and cooling single crystals of cryogenic solids along the solid-vapor saturation line while maintaining a condition of negligible mechanical strain. The crystal volumes were ∼50 mm3 and optical access was provided for application of Brillouin and Raman spectroscopies. Single-crystal studies of CH4 and CD4 have been completed over the temperature range from the triple point (∼90 K) down to approximately 15 K. In the case of CD4 three distinct solid phases were involved. © 1999 American Institute of Physics.
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    Performance of new infrared beamline U12IR at the National Synchrotron Light Source (1999)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 70 (1999), S. 2899-2904 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: The instrumentation and performance of the new infrared beamline U12IR at the National Synchrotron Light Source of Brookhaven National Laboratory is described. This beamline utilizes infrared synchrotron radiation from a bending magnet. A combination of beamline design features and spectroscopic instrumentation allows the facility to reach the extremely low frequency limit of ∼2 cm−1 (i.e., 60 GHz or a photon energy of 250 μeV). The infrared light from the synchrotron emission at U12IR is compared to standard thermal sources and reveals substantial benefits for the study of small samples. In particular, the intensity of the synchrotron radiation in the far infrared can be as much as 200 times greater than that from a blackbody when millimeter-sized samples are measured. The effects of diffraction and noise on beamline performance are also discussed. © 1999 American Institute of Physics.
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    Characterization and stabilization of fiber-coupled laser diode arrays (1999)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 70 (1999), S. 2905-2909 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: We have characterized the spectra and performance of an ensemble of 11 fiber-coupled laser diode arrays (LDAs) manufactured by Opto Power Inc. These high-power LDAs operate near 795 nm and are of a type commonly used for spin-exchange optical pumping of noble gases. We find the Opto Power LDAs to vary significantly in output power, spectral width, and other important characteristics, in a manner not correlated with age, operating lifetime, or information supplied by the manufacturer. In addition we have developed a two-loop feedback technique for use with LDAs that stabilizes the Rb magnetization in an optical pumping cell to better than one part in a thousand. © 1999 American Institute of Physics.
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    URL: http://dx.doi.org/10.1063/1.1149847
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    New fiber-optic attenuator calibration technique using linear intensity modulation characteristics of a laser diode (1999)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 70 (1999), S. 2910-2911 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: A new fiber-optic attenuator calibration technique has been developed using linear intensity modulation characteristics of a laser diode. It does not require detector linearity to be known. The uncertainty of attenuation calibration for a typical 10 dB attenuator is 0.020 dB at two standard deviation levels. The resolution of the system is 0.001 dB and the dynamic range is 25 dB in a single step. © 1999 American Institute of Physics.
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    URL: http://dx.doi.org/10.1063/1.1149848
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    Group-phase refractive index method for improving the accuracy in two-color interferometric length measurements (1999)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 70 (1999), S. 2917-2920 
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    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: A group-phase refractive index method was developed for improving the accuracy of a conventional two-color method used in an interferometer for length measurements. This method uses two closer wavelengths to reduce the errors caused by air turbulence and the chromatic aberration. We describe the new method and demonstrate preliminarily its effectiveness by measuring the group refractive index of air using a vacuum cell. We then compared the results with those calculated using the Edlén equation. The mean difference between the measured and calculated values was 2.15×10−6 with a standard deviation of 2.0×10−6 for the vacuum cell with a length of 184.5 mm. © 1999 American Institute of Physics.
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    URL: http://dx.doi.org/10.1063/1.1149850
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    Silicon-anode detector with integrated electronics for microchannel-plate imaging detectors (1999)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 70 (1999), S. 2912-2916 
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    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: We describe a silicon anode with integrated electronics for use in photon-counting microchannel-plate (MCP) imaging detectors. Very-large-scale integrated techniques using a 2 μm complementary metal–oxide–semiconductor (CMOS) process allow a passive-anode region, which collects charge from the MCPs, to be surrounded by an active event-processing region. The anode region is made from a rectangular array of pads that are formed using the metal interconnect layers of the CMOS process. Individual pads are electrically connected to form isolated arrays of rows and columns; each row terminates at a well of one charge-coupled device (CCD) register, and each column terminates at a well of a second orthogonal CCD register. The distribution of charge within each register is used to encode the charge-cloud coordinates. A two-dimensional prototype anode was constructed with 128×80 pixels spaced at 50 μm intervals; the anode readout rate is 31 250 Hz. Subpixel centroiding techniques can be employed to reduce the number of pixels that must be read for a given resolution. We envision a rugged, compact, low-power, and low-mass single-substrate imaging anode with a direct (x,y) digital interface. The design offers large array formats with inherent pixel linearity, orthogonality, and stability. An identified upgrade path promises orders-of-magnitude increases in speed (up to 106 photons s−1) and dynamic range, while maintaining large pixel count (〉4000×4000) and MCP pore-limited resolution (〈8 μm). © 1999 American Institute of Physics.
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    URL: http://dx.doi.org/10.1063/1.1149849
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    A calibration method of a radio frequency magnetic probe (1999)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 70 (1999), S. 3774-3775 
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    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: We demonstrate a simple calibration method of a rf magnetic probe by utilizing a two port network analysis method. The sensitivity (V/G) of the probe is determined by measuring the scattering parameters of S11 and S21. The magnetic field generated by the Helmholtz coil is calculated from S11 and the probe sensitivity is obtained from S21. The measured probe sensitivity is 0.1–0.6 V/G in the frequency range of 1–15 MHz. © 1999 American Institute of Physics.
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    URL: http://dx.doi.org/10.1063/1.1149951
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    A method for measuring low capacitance for tomography (1999)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 70 (1999), S. 3177-3179 
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    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: The applications of electrical capacitance tomography (ECT) to image multiphase flows in pipelines, fluidization process, interfaces in separation vessels, and combustion phenomena in internal combustion engines have been studied for some years. In these applications, none of the equipment imaged has an inner diameter exceeding 1 m. When ECT techniques for large industrial equipment like blast furnaces are explored, the existing methods for measuring low capacitance have some limitations. This article proposes a method for measuring low capacitance which is suitable to construct ECT systems for imaging large industrial equipment. The method is based on single high-voltage excitation and magnetic C/V converting principle which can resist interference by stray capacitance. Experiment results indicated that the method has good performance in regard to resolution, linearity, and stability. Though the method was designed for imaging large equipment, it can also be applicable to other fields where low capacitance measurements are required. © 1999 American Institute of Physics.
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    URL: http://dx.doi.org/10.1063/1.1149883
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    A new simple compact refractometer applied to measurements of air density fluctuations (1999)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 70 (1999), S. 3160-3166 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: We describe a new simple, compact refractometer for air refractive index measurements. It consists of a double plane–plane Fabry Perot interferometer. Both interferometers consisting of Zerodur spacers of thickness of 1 and 100 mm are illuminated independently by the same single mode laser diode. The shorter cavity allows unambiguous identification of the transmission peak of the longer one to which the laser frequency is servo-locked. The refractive index of air is obtained via a heterodyne comparison with a second laser locked to a hyperfine component of the rubidium D2 line. We obtain a resolution of order 10−10 and accuracy of a few times 10−8. The metrological characteristics of the interferometer in vacuum are presented. Initial results for refractive index measurements agree with values calculated using the revised Edlen formulas. We also describe how this refractometer is used to measure variations of the density of air and their correlation with changes of refractive index of air. The density of air is used to make buoyancy corrections when comparing mass standards of different volume. Our preliminary results indicate that the values of air density determined by refractometry agree with those calculated using the Comité International des Poids et Mesures formula, which is based on measurements of temperature, pressure, moisture content, and CO2 concentration. © 1999 American Institute of Physics.
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    URL: http://dx.doi.org/10.1063/1.1149880
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    Introduction to time and frequency metrology (1999)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 70 (1999), S. 2567-2596 
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    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: In this article, I will review the definition of time and time interval, and I will describe some of the devices that are used to realize these definitions. I will then introduce the principles of time and frequency metrology, including a discussion of some of the types of measurement hardware in common use and the statistical machinery that is used to analyze these data. I will also introduce various techniques of distributing time and frequency information, with special emphasis on the global positioning system satellites. I will then discuss the advantages of clock ensembles and a prototype time-scale algorithm. I will conclude with a discussion of how clocks are synchronized to remote servers using noisy and poorly characterized transmission channels.
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    URL: http://dx.doi.org/10.1063/1.1149844
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    The operation and modeling of transmission line transformers using a referral method (1999)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 70 (1999), S. 3180-3185 
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    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: This article describes the modeling of transmission line transformers using methods which are analogous to the methods used to analyze both the ac frequency and transient response of conventional transformers. Transformers in which the lines used to construct them are wound inductively, in order to suppress parasitic short circuit paths within the transformers, are analyzed. It is shown that by using this technique the resulting inductive isolation of the secondary circuit from the primary substantially reduces pulse droop and pulse distortion. Despite the apparent complexity of these transformers, a method by which circuit models of these transformers can be deduced is given. From these models very simple equivalent circuits can be derived which can then be used to calculate accurately the performance characteristics of the transformers and, in particular, predict the pulse distortion characteristics of these devices. Different winding configurations are also considered and it is shown that, by the use of mutually coupled winding of the transmission lines in the transformer, it is possible to minimize pulse droop. Finally it is shown that the modeling technique can be used, in modified form, to analyze the ac frequency response of this type of transformer. © 1999 American Institute of Physics.
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    A simple technique using the diffraction pattern of a shadow region for the evaluation of a vertex of a wedge having an acute angle (1999)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 70 (1999), S. 2880-2881 
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    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: The dependence of the diffraction in the shadow on the finish of a vertex of a wedge having an acute angle is studied experimentally. The length of a rounded top can be obtained by analyzing the diffraction intensity along the vertical line from the vertex. This method is a valuable technique for evaluating the finish of a vertex of a small wedge having an acute angle. It is found that this technique makes the evaluating system simple. © 1999 American Institute of Physics.
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    URL: http://dx.doi.org/10.1063/1.1149813
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    Design and operation of different optical fiber sensors for displacement measurements (1999)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 70 (1999), S. 2875-2879 
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    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: Design and operation of different intensity modulated extrinsic optical-fiber sensors are reported. A cantilever fiber-to-fiber, as well as a fiber-lens-fiber design is arranged and studied experimentally. The third scheme introduces a fiber-lens-double fiber design in which a double fiber is used for the light detection. In each case, a stepper motor driven micrometer system is used for the small displacement variations of the cantilever fiber or the ball lens. The results obtained for these sensors are checked against each other, advantages and disadvantages are explored, and the optimum sensor design for such a measurement is proposed. © 1999 American Institute of Physics.
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    Simple method to reduce the dead time of multichannel analyzers (1999)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 70 (1999), S. 2882-2883 
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    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: A method to reduce the dead time of multichannel analyzers which uses multiple sample-and-hold circuits in the input circuitry of the analyzer's analog-digital converter is proposed. Due to the exponential distribution of time intervals between successive pulses, the dead time is greatly reduced with even a small number of sample-and-hold circuits. The effects of the method are analyzed and discussed by means of Monte Carlo simulations. © 1999 American Institute of Physics.
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    Spatial distribution of electron cloud footprints from microchannel plates: Measurements and modeling (1999)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 70 (1999), S. 3282-3288 
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    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: The measurements of the electron cloud footprints produced by a stack of microchannel plates (MCPs) as a function of gain, MCP-to-readout distance and accelerating electric field are presented. To investigate the charge footprint variation, we introduce a ballistic model of the charge cloud propagation based on the energy and angular distribution at the MCP output. We also simulate the Coulomb repulsion in the electron cloud, which is likely to cause the experimentally observed increase in the cloud size with increasing MCP gain. Calculation results for both models are compared to the charge footprint sizes measured both in our experiments with high rear-field values (∼200–900 V/mm) and in the experiments of Edgar et al. [Rev. Sci. Instrum. 60, 3673 (1989)] (accelerating electric field ∼30–130 V/mm). © 1999 American Institute of Physics.
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    A compact electron energy analyzer for measuring field emission energy distributions (1999)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 70 (1999), S. 3299-3302 
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    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: A simple instrument to determine field emission tip work functions and shape functions from simultaneous current–voltage (I–V) characteristics and field emission energy distributions of field emitter tips and tip arrays is described. This instrument uses a cylindrical energy analyzer with a few correcting elements to simulate a hemispherical analyzer and provides a low cost and more compact alternative to a commercial hemispherical spectrometer. I–V curves and energy distributions may be automatically obtained as a function of time to study field emission tip degradation with usage and/or exposure to gases of interest. © 1999 American Institute of Physics.
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    URL: http://dx.doi.org/10.1063/1.1149907
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    Using the induced axial magnetic field to measure the root mean square beam size and beam density uniformity of an electron beam in an induction linac (1999)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 70 (1999), S. 3308-3313 
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    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: An intense electron beam in a solenoidal axial magnetic field rotates azimuthally, and generates a diamagnetic axial field that counteracts the applied field. However, the magnetic flux within the beam pipe is conserved over sufficiently short times, and this induced diamagnetic field must lead to an increase in the axial field outside the beam, which is measurable with a loop or an optical Faraday rotator. If the applied axial magnetic field is uniform across the beam pipe, the measurement directly leads to the rms transverse beam size. However, if the axial magnetic field has sinusoidal components, measurement of the diamagnetic field at two axial positions yields both the beam's rms transverse size and the beam's fourth radial moment. Comparison of these moments can give a figure of merit of the beam's density uniformity. © 1999 American Institute of Physics.
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    The characteristics of the newly designed microchannel plate detector in a strong magnetic field (1999)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 70 (1999), S. 3319-3323 
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    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: A gold neutral beam probe system which uses a microchannel plate (MCP) as a beam detector is being constructed in order to measure the electrostatic potential at the inner mirror throat (IMT) of the plug/barrier cell in the tandem mirror. The MCP detector was newly designed so as to be able to be used in the IMT strong magnetic field. The characteristics of the MCP gain were measured on a test stand with the strong magnetic field. The characteristic curves of the relative MCP gain were described as functions of the magnetic field strength, the MCP bias voltage, and the angle between the magnetic field and the capillary axis of the MCP. It was found that the newly designed MCP detector was useful for the potential measurement at the IMT region. © 1999 American Institute of Physics.
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    URL: http://dx.doi.org/10.1063/1.1149911
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    Large area and high sensitivity a-Si:H/a-SiC:H based detectors for visible and ultraviolet light (1999)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 70 (1999), S. 2235-2237 
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    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: In this article we discuss the fabrication and performance of a-Si:H/a-SiC:H based ultraviolet sensitive devices. They were deposited over a large area (10 cm×10 cm) in p-i-n configuration using a new, multichamber, ultrahigh vacuum plasma enhanced chemical vapor deposition facility. The intrinsic layer thickness was 10–100 nm. The devices were characterized in the spectral range 365–660 nm and showed good sensitivity in the UV (365 nm). A good rejection of visible light was also measured. Responsivity as high as 0.30 A/W was measured at 365 nm for samples where the p layer and i layer were 5 and 10 nm thick, respectively. The linearity of the photogenerated current as a function of photon flux was measured. It was found that over an area of 25 cm2 the uniformity was within 15%. Using a laser (200 mW at 351 and 363 nm) the aging characteristics were measured and showed a 25% decrease in responsivity after the absorption of 105 J cm−2 under operating conditions. © 1999 American Institute of Physics.
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    Nanometer focusing of hard x rays by phase zone plates (1999)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 70 (1999), S. 2238-2241 
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    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: Focusing of 8 keV x rays to a spot size of 150 and 90 nm full width at half maximum have been demonstrated at the first- and third-order foci, respectively, of a phase zone plate (PZP). The PZP has a numerical aperture of 1.5 mrad and focusing efficiency of 13% for 8 keV x rays. A flux density gain of 121 000 was obtained at the first-order focus. In this article, the fabrication of the PZP and its experimental characterization are presented and some special applications are discussed. © 1999 American Institute of Physics.
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    A low-temperature dynamic mode scanning force microscope operating in high magnetic fields (1999)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 70 (1999), S. 2765-2768 
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    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: A scanning force microscope was implemented operating at temperatures below 4.2 K and in magnetic fields up to 8 T. Piezoelectric quartz tuning forks were employed for nonoptical tip–sample distance control in the dynamic operation mode. Fast response was achieved by using a phase-locked loop for driving the mechanical oscillator. Possible applications of this setup for various scanning probe techniques are discussed. © 1999 American Institute of Physics.
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    Femtosecond pump-probe near-field optical microscopy (1999)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 70 (1999), S. 2758-2764 
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    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: We have developed an instrument for optically measuring carrier dynamics in thin-film materials with ∼150 nm lateral resolution, ∼250 fs temporal resolution, and high sensitivity. This is achieved by combining ultrafast pump-probe laser spectroscopic techniques, which measure carrier dynamics with femtosecond-scale temporal resolution, with the nanometer-scale lateral resolution of near-field scanning optical microscopes (NSOMs). We employ a configuration in which carriers are excited by a far-field pump laser pulse and locally measured by a probe pulse sent through a NSOM tip and transmitted through the sample in the near field. A novel detection system allows for either two-color or degenerate pump and probe photon energies, permitting greater measurement flexibility over earlier published work. The capabilities of this instrument are proven through near-field degenerate pump-probe studies of carrier dynamics in GaAs/AlGaAs single quantum well samples locally patterned by focused-ion-beam (FIB) implantation. We find that lateral carrier diffusion across the nanometer-scale FIB pattern plays a significant role in the decay time of the excited carriers within ∼1 μm of the implanted stripes, an effect which could not have been resolved with a far-field system. © 1999 American Institute of Physics.
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    Manipulation force microscopy (1999)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 70 (1999), S. 2769-2775 
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    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: The manipulation force microscope is a novel atomic force microscope adapted to measuring the force necessary to displace micron-size samples adhering to surfaces. It has successfully characterized the adhesion of both proteins and living cells to substrates. This instrument enables measurement of samples not previously accessible to atomic force microscopes. Here, we give a detailed account of this new method, and report on computer simulations and models to assist the interpretation of data. © 1999 American Institute of Physics.
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    A high resolution long travel friction-drive micropositioner with programmable step size (1999)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 70 (1999), S. 2776-2782 
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    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: A piezoelectric-driven Scott–Russel linear micropositioner utilizing the stick-slip effect of friction to drive a slider is presented. Effects of sawtooth, impulse, and transcendental electrical wave forms on the device performance are studied via numerical simulation and experiment test. The experiment demonstrates that positioning step sizes of 0.05–120 μm can be achieved at low input voltages of 2–25 V and essentially with unlimited travel range. © 1999 American Institute of Physics.
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    Enhancing electron beam induced current images (1999)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 70 (1999), S. 2793-2795 
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    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: Image processing techniques can be used on electron beam induced current (EBIC) images to reveal information hidden in the images. The method proposed in this article is similar to that used in ion beam induced charge collection in which different signal strengths are channelled to different windows. An image processing algorithm has been developed to mimic the effect of separating different signal strength into different windows. On top of that, the algorithm also stretches the strength of the signal, and this greatly enhances the capability of the technique. An EBIC image of a transistor is used to demonstrate this technique and the results are presented in this article. © 1999 American Institute of Physics.
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    Nondestructive superresolution imaging of defects and nonuniformities in metals, semiconductors, dielectrics, composites, and plants using evanescent microwaves (1999)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 70 (1999), S. 2783-2792 
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    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: We have imaged and mapped material nonuniformities and defects using microwaves generated at the end of a microstripline resonator with 0.4 μm lateral spatial resolution at 1 GHz. Here we experimentally examine the effect of microstripline substrate permittivity, the feedline-to-resonator coupling strength, and probe tip geometry on the spatial resolution of the probe. Carbon composites, dielectrics, semiconductors, metals, and botanical samples were scanned for defects, residual stresses, subsurface features, areas of different film thickness, and moisture content. The resulting evanescent microwave probe (EMP) images are discussed. The main objective of this work is to demonstrate the overall capabilities of the EMP imaging technique as well as to discuss various probe parameters that can be used to design EMPs for different applications. © 1999 American Institute of Physics.
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    Noncontact technique for measuring surface tension and viscosity of molten materials using high temperature electrostatic levitation (1999)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 70 (1999), S. 2796-2801 
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    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: A new, noncontact technique is described which entails simultaneous measurements of the surface tension and the dynamic viscosity of molten materials. In this technique, four steps were performed to achieve the results: (1) a small sample of material was levitated and melted in a high vacuum using a high temperature electrostatic levitator, (2) the resonant oscillation of the drop was induced by applying a low level ac electric field pulse at the drop of resonance frequency, (3) the transient signals which followed the pulses were recorded, and (4) both the surface tension and the viscosity were extracted from the signal. The validity of this technique was demonstrated using a molten tin and a zirconium sample. In zirconium, the measurements could be extended to undercooled states by as much as 300 K. This technique may be used for both molten metallic alloys and semiconductors. © 1999 American Institute of Physics.
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    URL: http://dx.doi.org/10.1063/1.1149797
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    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
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: 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.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1150084
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    A new method for nondestructively monitoring the position of a charged particle beam in real time (1999)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 70 (1999), S. 2288-2292 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: The design and construction of a simple new device for nondestructively monitoring the position of an electron beam is described. By modulating a small portion of the electron-beam current, changes in the amounts of charge induced on the monitor electrodes are detected as currents. These currents are related to the location of the "center of charge" of the electron beam. Calculations and experimental results which illustrate the performance of the device are reported. This device is primarily intended for use in electron-beam ion sources and traps, although it could be applied to other situations where the beam current can be modulated. © 1999 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1149754
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    Measurements of thick target neutron yields and shielding studies using beams of 4He, 12C and 16O at 155 MeV/nucleon from the K1200 cyclotron at the National Superconducting Cyclotron Laboratory (1999)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 70 (1999), S. 2314-2324 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: Measurements of neutrons from a thick target of Hevimet were made, using beams of 4He, 12C, and 16O ions at 155 MeV per nucleon. These measurements were made both inside and outside of thick concrete shielding, using Bonner-sphere techniques. Yields, spectra, and spectral integral quantities were obtained. The neutron yields were parameterized, and a Moyer-model approach was taken to estimate the dose-equivalent outside of the thick concrete shielding. The effect of local iron shielding, and the dose equivalent outside of iron roof shielding were also investigated. Finally, two methods to obtain neutron field integral values, the "reconstructed spectra" and "six-spheres" methods, were compared. The measurements and analyses should prove useful to other present or planned medium-energy heavy-ion accelerator facilities.© 1999 American Institute of Physics.
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    URL: http://dx.doi.org/10.1063/1.1149757
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    Effects of filament positions on the arc discharge characteristics of a negative hydrogen ion source for neutral beam injector (1999)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 70 (1999), S. 2338-2344 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: The influence of filament positions on the arc discharge characteristics of a negative hydrogen ion source for a neutral beam injector were studied by simulations and experiments. We have made a simulation code named "PRIMELOC2," which calculates the orbits of primary electrons emitted from cathode filaments, including collisions with H2 gas molecules filled in the source, to obtain the spatial distribution of ionization points. We applied this code to a large negative hydrogen ion source having an external magnetic filter for LHD-NBI No. 1 (neutral beam injector 1 for a large helical device). As a result of the calculations, we have found that the moving area of emitted primary electrons differs markedly according to the filament positions. Calculation results agreed well with the experimental results of high-power arc discharge and the spatial distribution of plasma parameters obtained by Langmuir probe measurements. By applying PRIMELOC2 to filament–arc ion sources, we can choose appropriate areas in arc chambers for filament positioning. © 1999 American Institute of Physics.
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    URL: http://dx.doi.org/10.1063/1.1149760
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    Characterization of a high-density large scale pulsed gas jet for laser–gas interaction experiments (1999)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 70 (1999), S. 2349-2354 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: We present the characteristics of a high-density pulsed gas jet developed to study the interaction of a short-pulse, high-intensity laser with a large scale underdense plasma. The jet was characterized by laser interferometry. Measurements of density profile were performed for a 5 mm diam cylindrical nozzle and for a 20×1 mm slit. In this latter case, a systematic study of the output density as a function of the backing pressure and of the valve opening duration is presented. At 1 mm from its outlet, the cylindrical nozzle provides densities up to 6.9×1019 cm−3 for an 8 bar backing pressure with a 3 mm full width at half maximum Gaussian-shaped profile. Under the same conditions, the slit produces a 20 mm long flat-top profile with a maximum density of 2.1×1019 cm−3. © 1999 American Institute of Physics.
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    URL: http://dx.doi.org/10.1063/1.1149762
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    Nanometer-scale patterning and individual current-controlled lithography using multiple scanning probes (1999)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 70 (1999), S. 2822-2827 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: Scanning probe lithography (SPL) is capable of sub-30-nm-patterning resolution and nanometer-scale alignment registration, suggesting it might provide a solution to the semiconductor industry's lithography challenges. However, SPL throughput is significantly lower than conventional lithography techniques. Low throughput most limits the widespread use of SPL for high resolution patterning applications. This article addresses the speed constraints for reliable patterning of organic resists. Electrons field emitted from a sharp probe tip are used to expose the resist. Finite tip-sample capacitance limits the bandwidth of current-controlled lithography in which the tip-sample voltage bias is varied to maintain a fixed emission current during exposure. We have introduced a capacitance compensation scheme to ensure continuous resist exposure of SAL601 polymer resist at scan speeds up to 1 mm/s. We also demonstrate parallel resist exposure with two tips, where the emission current from each tip is individually controlled. Simultaneous patterning with multiple tips may make SPL a viable technology for high resolution lithography. © 1999 American Institute of Physics.
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    URL: http://dx.doi.org/10.1063/1.1149802
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    Coupling of gas chromatography and molecular beam/mass spectrometry analytical techniques: Application to flame structure study (1999)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 70 (1999), S. 2828-2835 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: A new experimental technique coupling both molecular beam and mass spectrometry (MBMS) and gas chromatography (GC) is developed to improve the analysis of low pressure reactive systems using a probe sampling procedure. The sensitivity of gas chromatography is greatly enhanced by using a compression procedure for the samples before injection into the chromatograph, and its selectivity allows one to separate isomers and to study very complex mixtures. By contrast MBMS is well suited to atoms and radical species detection. Moreover, the temperature dependence of the fragmentation pattern of heavy hydrocarbons during MBMS ionization is pointed out and it can be resolved alternatively by GC calibration. The complementarity of these two analytical techniques is demonstrated in the case of low pressure natural gas flames study. © 1999 American Institute of Physics.
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    URL: http://dx.doi.org/10.1063/1.1149803
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    Miniaturized scintillation technique for protein solubility determinations (1999)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 70 (1999), S. 2845-2849 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: We have developed a miniaturized (volume of crystallizing solution ∼100 μl) technique for the determination of protein solubility as a function of temperature. After nucleation, crystals are detected by the light they scatter. Then the temperature at which a solution with the initial concentration is in equilibrium with the crystals is sought by stepwise, equilibrium dissolution of the crystals. The approach to solubility from the side of dissolution provides for higher accuracy of the determinations. The method was used to determine the temperature dependence of the solubility of human hemoglobin (Hb) C, for which high-resolution x-ray crystallography data are needed to understand the structural basis for the drastically different in vivo aggregation/crystallization behavior of β6 Hb mutants. © 1999 American Institute of Physics.
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    URL: http://dx.doi.org/10.1063/1.1149805
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    Fabrication and evaluation of a dimension-reduction fiberoptic system for chemical imaging applications (1999)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 70 (1999), S. 2836-2844 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: A novel system for rapid chemical imaging is described and evaluated. The system operates via single-frame spectroscopic chemical imaging with high spectroscopic resolution using a second-generation dimension-reduction fiberoptic array. Images are focused onto a rectangular array of square close-packed 25 μm cross-sectional f/2 optical fibers that are drawn into a linear distal array with serpentine ordering. The distal end is then imaged with an f/2 spectrograph equipped with a holographic grating and a gated intensified charge-coupled device (ICCD) camera for analysis. Software is used to extract the spatial/spectral information contained in a single ICCD image and deconvolute it into wavelength-specific univariate reconstructed images or position-specific spectra that span an 86 nm wavelength space using our present grating. A description of the fabrication of the dimension-reduction array is given as well as a zero-order reconstruction of a binary target and single-wavelength image reconstructions of a laser-induced plasma. The system is evaluated for spatial and spectral resolution, throughput, image brightness, resolving power, depth of focus, and channel cross talk. Treatment of the spectroscopic data obtained from the ICCD images for use in potential chemical imaging applications is discussed. © 1999 American Institute of Physics.
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    URL: http://dx.doi.org/10.1063/1.1149804
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    Teeth mobility measurement by laser Doppler vibrometer (1999)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 70 (1999), S. 2850-2855 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: In this work a new procedure for the assessment of teeth mobility, based on a noncontact sensor (laser Doppler vibrometer), is presented. The procedure is based on the manual application of impulses applied with an instrumented hammer on the tooth crown. The ratio of the maximum displacement of the tooth to the peak of the input force has been considered as the mobility degree index. A basic mechanical model of the hammer-tooth impact based on the data extracted from literature has been realized. Results produced with the model mentioned above have been compared with those measured with in vitro and in vivo tests using the proposed procedure. Good agreement between data from the mechanical model and in vitro conditions has been found. Tests carried out in in vitro and in vivo conditions have demonstrated the validity of the procedure proposed. Measurement results compared to those found in the relevant literature show the validity of the procedure proposed. © 1999 American Institute of Physics.
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    URL: http://dx.doi.org/10.1063/1.1149806
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    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
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: 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.
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    URL: http://dx.doi.org/10.1063/1.1149808
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    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
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: 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.
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    URL: http://dx.doi.org/10.1063/1.1149807
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    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
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: 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.
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    URL: http://dx.doi.org/10.1063/1.1149809
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    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
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: 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.
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    The theory of operation of transistorized Marx bank circuits (1999)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 70 (1999), S. 2155-2160 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: A theory of operation of transistorized Marx bank circuits has been formulated. It has been shown quantitatively that the current-mode second breakdown of transistors is the basic phenomenon involved. The analysis reveals that physical parameters, like the length of and the doping density in the epitaxial collector, the forward dc amplification factor, and the avalanche multiplication gain of the transistors, play important roles in the mechanism. The theory has been applied to explain a number of experimentally observed characteristics of the circuit. © 1999 American Institute of Physics.
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    URL: http://dx.doi.org/10.1063/1.1149729
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    Dielectric-insensitive capacitive differential pressure gauge for use at low temperature (1999)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 70 (1999), S. 2161-2165 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: A capacitive differential pressure gauge for use at temperatures below 4 K is described. Fluid is admitted to two sample chambers with flexible walls to which a sensing capacitor is mechanically connected. Differential pressures between the chambers flex these walls and change the capacitance of the gauge. Because the capacitor is located outside these chambers, the gauge is insensitive to the dielectric variations of the fluid. Typical differential pressures of 105 Pa were measured with a common mode rejection ratio in excess of 50. © 1999 American Institute of Physics.
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    Fiberoptic displacement sensor with a short hollow metal optical waveguide (1999)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 70 (1999), S. 2166-2168 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: A fiberoptic displacement sensor is described that is based on a combination of a pair of emitter and receiver fibers and a short hollow metal waveguide. The role of the hollow metal waveguide and its influence on the sensor characteristics are studied experimentally. It is shown that adding such a waveguide changes the shape of the sensor's output signal and increases its amplitude by more than a factor of two. The optimum length of the metal optical waveguide that ensures improved sensor's parameters is also estimated. The proposing sensor scheme can modify and improve the parameters of a large variety of fiber optic sensors that employ the same emitter-receiver fiber arrangement. © 1999 American Institute of Physics.
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    URL: http://dx.doi.org/10.1063/1.1149532
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    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
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: 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.
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    URL: http://dx.doi.org/10.1063/1.1149730
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    A novel analog current-conveyor multiplier circuit (1999)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 70 (1999), S. 2171-2172 
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    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: 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.
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    A simple, high sensitivity torquemeter (1999)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 70 (1999), S. 2732-2734 
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    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: A simple torquemeter has been developed with a sensitivity exceeding 10−13 Nm when using a 13-μm-diam glass fiber and a low-mass suspension. The maximum twist angle of the fiber is constrained by the choice of its diameter to ∼1°. This angle is measured using a light, mirror, and split silicon photodetector, and is proportional to the torque on a sample in a rotating dc magnetic field. © 1999 American Institute of Physics.
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    InAs/Al0.2Ga0.8Sb quantum well Hall sensors with improved temperature stability (1999)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 70 (1999), S. 2715-2718 
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    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: Cross-shaped Hall sensors with high sensitivity and excellent temperature stability were fabricated from quantum wells based on an InAs/Al0.2Ga0.8Sb heterostructure. The layers were grown on semi-insulating GaAs substrates by molecular beam epitaxy. Maximum Hall mobilities of 215 000 cm2/V s with sheet carrier concentrations of 9×1011 cm−2 were measured at 4.2 K for an undoped quantum well structure. These transport properties result in sensitivities as high as 3 T−1 (for voltage drive) and 650 Ω/T (for current drive). Additional Si δ doping in the middle of the InAs quantum well leads to a highly improved temperature stability of the sensitivities. © 1999 American Institute of Physics.
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    URL: http://dx.doi.org/10.1063/1.1149834
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    Specific heat (Cp) of Apiezon N grease (1 to 108 K) and calorimetry: Cp of copper below 30 K (1999)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 70 (1999), S. 2728-2731 
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    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: Heat capacity (Cp) data for Apiezon N grease from 1 to 108 K are compared with previous results for this grease and for Apiezon T, with good agreement. Addenda results for a calorimeter in which Apiezon N grease is used for thermal contact between the tray and a sample suggest that a thin film of this grease has an appreciably larger Cp, below 4 K, than bulk grease. For high accuracy experiments using Apiezon N grease, care should be taken in the calculation of addenda Cp's from bare tray data and the Cp for bulk grease. During these measurements, Cp data for a high purity electron beam melted copper sample were found to be in excellent agreement from 1 to 30 K (±0.2%) with previous measurements [Holste, Cetas, and Swenson, Rev. Sci. Instrum. 43, 670 (1972)] on a different sample using a quite different calorimeter. © 1999 American Institute of Physics.
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    Measuring temperatures in the presence of external radiation by flash assisted multiwavelength pyrometry (1999)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 70 (1999), S. 2719-2727 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: A novel multiwavelength analysis of the radiation emitted by a hot Lambertian surface is presented allowing a reliable measurement of its surface temperature even in the presence of interfering external light sources. For the separation of thermally emitted and reflected external radiation, an accurate knowledge of the spectral emittance/reflectance of the sample is required. In our procedure, this quantity is determined in situ by performing a second measurement with additional light, e.g., from a strong electric flash. The strength of the flash and the relative spectrum of the interfering external radiation are probed with a cooled Lambertian reflectance reference near the sample. In a first step, the spectral reflectance of the sample is determined from spectra recorded with and without flash. The temperature and the total incoming irradiance are then obtained from a least-square fit of the input spectra with an analytical model of the emitted thermal plus the superimposed reflected external radiation. The method delivers also estimates for the statistical accuracy of the measured temperature and irradiance values. It causes no problem to measure temperatures through a window of sufficient optical quality and effects of absorbing gases or vapors may be minimized by an appropriate choice of the spectral intervals used for the analysis. In order to indicate statistical and systematic errors of the method under different operating conditions, extensive numerical simulations were performed. They reveal that a good statistical accuracy of the recorded spectra is crucial for a proper separation of the emitted from the reflected external radiation if one part dominates. In contrast, this separation is not affected by an erroneous calibration of the optical detection system. Finally, the question is discussed if one can dispense with the flash. Without external radiation, the "no-flash" method is equivalent to quotient pyrometry and subject to the same principal limitations. With external radiation, reasonably accurate temperatures can be expected only if thermal radiation clearly dominates or if emittance values are available from other sources. © 1999 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1149835
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    Active low frequency vertical vibration isolation (1999)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 70 (1999), S. 2735-2741 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: We have constructed a system that isolates a key element of our experimental setup from vertical motions of the ground and the surrounding apparatus. This system combines the passive isolation of mechanical springs and an optical table floating on compressed air with an active system that measures the acceleration of the mass to be isolated and feeds back to a solenoid actuator to cancel this motion. Passive isolation alone reduces the acceleration error signal by a factor of 30–1000 from 10 to 100 Hz and by as much as a factor of 1000 above 100 Hz. With the feedback path closed, the system acts like a spring-mass system with a natural resonance frequency of 0.033 Hz. The acceleration error signal is reduced by an additional factor of up to 300 from 0.1 to 20 Hz. This system has enabled us to make precision atom interferometric measurements that would have been impossible without vibration isolation. © 1999 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1149838
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  • 94
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    Design of a beamline for soft and deep lithography on third generation synchrotron radiation source (1999)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 70 (1999), S. 1605-1613 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: ELETTRA is a third generation synchrotron radiation source. The energy spectrum allows the design of beamlines suitable for x-ray lithography from soft to hard x-ray wavelengths. An appropriate lithographic window for micro- and nanofabrication can be obtained by a combination of selected filters and mirrors. As the beamline is interfaced to a vertical x-ray stepper, a uniformity in the beam intensity better than 3% (3σ) in the horizontal direction has to be reached. The present beamline is designed by taking into account the main factors which can affect the beam quality, namely, thermal loading on mirrors and filters, slope errors, and surface roughness of the mirrors. The resulting lithographic resolution at soft x-ray wavelengths is better than 100 nm. © 1999 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1149640
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  • 95
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    Launched wave packets in an ion beam-plasma system (1999)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 70 (1999), S. 1986-1990 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: A generation mechanism of wave packets and measurement of the launched wave packets using Langmuir probes in an ion beam-plasma system are presented. The origin of the wave packets appears to be the Johnson noise of a resistor in a simple amplifying circuit. The measured wave packets were found to propagate on the slow beam mode. © 1999 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1149699
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  • 96
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    Millimeter wave polarimeter for characterizing high-power plasma heating systems (1999)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 70 (1999), S. 1994-1998 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: We have built a millimeter wave polarimeter which measures wave polarization parameters: the polarization angle, and the ellipticity including field spin direction in an evacuated high-power system. The polarimeter was applied to diagnose the 1 MW level electron-cyclotron plasma heating system at 110 GHz for the DIII-D tokamak. We have observed the time-dependent behavior of the gyrotrons and have characterized and calibrated the high-power transmission system which consists of grooved mirror polarizers, miter bends, switches, and corrugated wave guides. This article describes the principle of operation and the design method of the polarimeter and the examples of measurements. © 1999 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1149701
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  • 97
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    Beam optics of the SINGAP 1 MeV 100 mA D− direct current accelerator for thermonuclear fusion (1999)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 70 (1999), S. 1991-1993 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: Injection of intense neutral beams (e.g., ITER up to 50 MW of neutral power) based on the neutralization of negative deuterium ions up to energies of 1 MeV is an important option for plasma heating and noninductive current drive in future thermonuclear fusion machines. The objective of the SINGAP experiment is to demonstrate the acceleration of 100 mA of D− to 1 MeV in an electrostatic accelerator concept. It is composed of only two acceleration stages: a preacceleration to 60 keV in a multiaperture structure, and a postacceleration to 1 MeV. The particular feature of the SINGAP accelerator is that the postaccelerator by means of an electrostatic lens merges the 60 keV beamlets into a single beam and accelerates the merged beam to 1 MeV in a single gap. The present article is devoted to the SINGAP optics study (simulation and experiment) for two geometric configurations: cylindrical and rectangular (more ITER relevant). Despite a higher measured divergence (8 mrad) than expected (4–5 mrad calculated) which is due to the magnetic field of the electron suppression system, this study has proved that the SINGAP concept can meet the optical requirement (divergence 〈5 mrad) for multiamperes injectors. © 1999 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1149700
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  • 98
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    Noise averaging and measurement resolution (or "A little noise is a good thing") (1999)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 70 (1999), S. 2038-2040 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: When a continuous quantity is measured with a digital instrument or digitized for further processing, a measurement uncertainty component is incurred from quantization of the continuous variable. This uncertainty can be reduced by oversampling and averaging multiple measurements, but only if there is some noise on the measurand. In this article the optimum noise level is determined, and the subsequent improvement in measurement uncertainty calculated.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1149735
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  • 99
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    Materials selection for the in situ mirrors of laser diagnostics in fusion devices (1999)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 70 (1999), S. 2016-2025 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: When mirrors for the laser scattering diagnostic for large fusion devices need to be inside the vacuum chamber, they are subjected to irradiation by multiple high-energy laser pulses and bombardment by charge exchange atoms. Both of these assaults are known to degrade and eventually damage metal laser mirrors given sufficient time and flux. Our aim in this article is to use current data on these damage mechanisms to make design selections of metal mirror materials for application in fusion device diagnostics. We identify tradeoffs between low sputtering rates and multipulse laser damage resistance in candidate metals. The data for multipulse laser damage are incomplete and extend to a maximum of only 104 shots for a few metals. However, there is a clear trend of decreasing laser-damage threshold with increasing number of shots, and damage threshold fluences can fall to 10% of the single-pulse damaging laser fluence. Further experiments up to 106 or 108 laser shots need to be conducted on the likely mirror candidate metals for use in new plasma devices. We define a figure-of-merit based on current laser damage data and employ it in our analysis. Recent data on the sputtering yield and reflectance degradation of metal mirrors give a different priority ranking of candidate metals. Overall, the preferred material selection depends on the number of laser shots and the number of plasma pulses that the mirror must endure before replacement is allowed. For example, we find that for conditions typical of the LHD (10 s plasma pulses with a 10 Hz laser PRF), Au, Ag, and Cu are candidate materials if mirrors are replaced after 103 plasma pulses; Au and Rh are candidates if the replacement interval is 104 pulses; and if the replacement interval is further increased to 105 plasma pulses, then Mo is the candidate material. Other materials might also be candidates but the data on them are still insufficient. © 1999 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1149704
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  • 100
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    Laser scanning microscope for low temperature single molecule and microscale spectroscopy based on gradient index optics (1999)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 70 (1999), S. 2041-2045 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: A scanning optical microscope for low temperature imaging and spectroscopy with a gradient index rod-shaped microlens as an objective lens is presented. The solid immersion effect enhances the resolution to 310 nm of the full-width at half-maximum at the wavelength of 545 nm. Laser scanning mechanism located outside an optical cryostat enables to achieve large scanning ranges independent of temperature. The performance is demonstrated at 1.6 K on single molecules of terrylene in a dodecane crystal and on molecular J aggregates in thin polymer films. © 1999 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1149707
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