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  • Articles  (6,434)
  • American Institute of Physics (AIP)  (6,434)
  • American Chemical Society
  • Public Library of Science
  • 2020-2022
  • 1990-1994  (6,434)
  • 1970-1974
  • Electrical Engineering, Measurement and Control Technology  (4,152)
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  • Articles  (6,434)
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  • 101
    Electronic Resource
    Electronic Resource
    Use of electron gun to regulate the radio-frequency plasma performance and beam optics : Proceedings of 5th international conference on ion sources (1994)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 65 (1994), S. 1454-1456 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: The addition of electrons in both rf plasma and ion beam extracted from a rf ion source enhanced the source's performance and beam optics. The increase of plasma intensity increases the charge state of the extracted ions. The mixing of electrons with the ions within the ion beam decreases the space charge effect on beam expansion.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1144942
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  • 102
    Electronic Resource
    Electronic Resource
    Electrostatic low-energy beam transport systems for the SSC linac (abstract)a) : Proceedings of 5th international conference on ion sources (1994)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 65 (1994), S. 1457-1457 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: This paper provides arguments to choose electrostatic low-energy beam transport (LEBT) over the magnetic LEBT for the SSC linac. We will outline the rules to design the electrostatic LEBTs with examples of SSC LEBTs.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1144943
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  • 103
    Electronic Resource
    Electronic Resource
    Measurements of discharge parameters of the ion source at high potential : Proceedings of fifth international conference on ion sources (1994)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 65 (1994), S. 1465-1467 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: The present measurement system is composed of signal preprocessors, an A/D conversion card, optical fibers, a microcomputer, and an interface. After discharge parameters of an ion source at high potential, i.e., analog signals, are preprocessed by means of LPF, amplitude limit, and normalization, they are changed into digital signals by A/D conversion. The digital signals are transferred through optical fibers to low potential, then they are gathered, processed, or stored by the microcomputer. The system can measure eight analog signals at high potential through scanning. Each measurement will take about 160 μs with a precision of ±1 LSB, i.e., ±0.4% maximum relative error at full range. Measurements of discharge parameters of the ion source at high potential were made for a steady state ion source and a high current pulse ion source successively, whose results are in good agreement with practical cases. The formation and propagation of interference and approaches of anti-interference under high current and high pulse voltage conditions are briefly described in the present article.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1144947
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  • 104
    Electronic Resource
    Electronic Resource
    Extension of the operation regime of an ion source (abstract) : Proceedings of 5th international conference on ion sources (1994)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 65 (1994), S. 1475-1475 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: In this work we present a method to lengthen the operation life of ion sources, according to the peculiarities of the particle beam which is required by the user. To reach this goal we have modified Popov's model and selected a fair variable that can be handled externally to prevent the break of the vacuum in the chamber. Our method could be applied to any kind of equipment containing an ion source, for instance, particle accelerators, ion implantors, neutron injectors, etc.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1144951
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  • 105
    Electronic Resource
    Electronic Resource
    High sensitivity Trouton–Noble experiment (1994)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 65 (1994), S. 788-792 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: The 1903 Trouton–Noble (TN) experiment, which sought a torque on a charged capacitor, is often regarded as the electrostatic equivalent of the Michelson–Morley experiment, inasmuch as it was supposed to have detected ether drift, and it yielded a null result. The present experiment was designed to be the electrostatic equivalent of the Michelson–Gale experiment, which was performed to detect the rotational velocity of the earth and which yielded a nonnull result. The present experiment is 105 times as sensitive as the original TN experiment, but yields a null result nonetheless. Although the TN experiment is often regarded as crucial, a footnote in the original paper reveals the conjectural nature of the theory.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1144955
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  • 106
    Electronic Resource
    Electronic Resource
    Laser-excited confocal-fluorescence gel scanner (1994)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 65 (1994), S. 807-812 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: A high-sensitivity, laser-excited, confocal-fluorescence scanner has been developed for the detection of fluorescently labeled nucleic acids separated on slab gels. The gel is placed on a motor-driven, two-dimensional scan stage and raster scanned past the optical detection system. The 488-nm argon ion laser beam is introduced into the confocal optical system at a long-pass dichroic beam splitter and focused within the gel to an ∼2 μm diameter spot by a high-numerical aperture microscope objective. The resulting fluorescence is gathered by the objective, passed back through the first long-pass beam splitter, and relayed to a second dichroic beam splitter that separates the red and green emissions. The fluorescence is then focused on confocal spatial filters to reduce stray and scattered light, passed through spectral filters, and detected with photomultipliers. The resulting signals are amplified, filtered, and digitized for display on a computer. This system can detect as little as 5×10−12 M fluorescein, the resolution as operated is 160 μm, and it can scan a 6 cm×6 cm gel using a scan rate of 4 cm/s in 12 min. The detection of DNA on slab gels, two-color DNA fragment sizing, and microtiter plate scanning are presented to illustrate some of the possible applications of this apparatus.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1144905
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  • 107
    Electronic Resource
    Electronic Resource
    Two-dimensional intensified photodiode array detector for spaceflight use (1994)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 65 (1994), S. 813-825 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: A two-dimensional, ultraviolet photon-counting detector suitable for spaceflight use, consisting of a microchannel plate intensifier coupled to a Reticon photodiode array, has been constructed and tested. The design is an extension of the one-dimensional detector flown on the Hopkins Ultraviolet Telescope. Extensive laboratory measurements have determined the operating characteristics of the detector and shown that it can successfully centroid with subdiode resolution. It was flown as part of an ultraviolet spectrometer on two sounding rockets, and successfully obtained long slit spectra of Comet Austin (1990 V) and the Io plasma torus surrounding Jupiter in the wavelength range of 1150–1850 A(ring). Details of the design, construction, testing, and flight performance of the detector are presented.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1144906
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  • 108
    Electronic Resource
    Electronic Resource
    Performance of the modified SX-700 plane grating monochromator at the Finnish beamline in MAX-lab (1994)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 65 (1994), S. 831-836 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: A soft x-ray beamline designed principally for gas phase measurements has been constructed and tested at the 550-MeV MAX I electron storage ring in Lund, Sweden. The beamline uses synchrotron radiation from a short 35-period undulator with a magnetic period of 24 mm. The photon energy range of the undulator is about 60–600 eV covering, e.g., the important C, N and O 1s ionization regions. The beamline is based on a modified SX-700 plane grating monochromator with a plane elliptical focusing mirror. The beamline has been tested by measuring total ion and electron yield spectra from the rare gases Kr and Ar in the resonance excitation regions just below the Kr M4,5 and Ar L2,3 ionization thresholds. These results show that the monochromator has very high resolution, E/ΔE≈4800 at 244 eV and ≈7600 at 91 eV, comparable with the best spherical and plane grating monochromators. The beamline is equipped with an effective differential pumping system for the gas phase experiments combined with a refocusing mirror in order to provide a small spot size (φ〈1 mm) at the sample region.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1145234
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  • 109
    Electronic Resource
    Electronic Resource
    Fiber-optic proton beam intensity monitor (1994)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 65 (1994), S. 865-870 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: The thermally induced change of the birefringence of a high-birefringence fused-silica optical fiber, when exposed to a proton beam (2 MeV, 0.5–44 nA, 5-mm spot diameter), was measured with a fiber-optic polarimetric sensor. A short length (5 cm) of 125-μ-diam, single-mode, polarization-maintaining optical fiber was put orthogonally to the beam in vacuo and the linear polarization of a HeNe laser beam launched into the fiber was analyzed by a polarizer and recorded by a photodetector. The response of the sensor both to a continuous and to a modulated proton beam was studied. The photodetector output, which varies with the cosine of the induced relative phase retardance between the fiber eigenmodes, provides a dc or an ac (10 Hz test modulation frequency) measurement of the beam current. This device acts as a proton beam intensity monitor, with minimum beam perturbation and a sensitivity of 0.1 nA. Its possible use also as a beam position monitor or as a wire-scanner beam profiler is suggested.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1144913
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  • 110
    Electronic Resource
    Electronic Resource
    Broadband time-domain-reflectometry dielectric spectroscopy using variable-time-scale sampling (1994)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 65 (1994), S. 887-891 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: Methods for increasing the bandwidth of time-domain-reflectometry (TDR) dielectric spectroscopy using variable-time-scale sampling are presented. Consecutive segments of the TDR transient are sampled with increasing time increments and the entire transient transformed into the frequency domain using a running Laplace transform. Instrumentation artifacts are identified and controlled by examining reflected transients for stray artifacts prior to transformation, either on individual time scales or on a composite log time scale. Transform algorithms are verified using spice simulation in both time and frequency domains. Results are presented for a conducting salt solution, showing continuous dielectric spectra from 100 kHz to 5 GHz in the frequency domain, and requiring acquisition over six decades of time in the time domain to capture the entire response.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1144917
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  • 111
    Electronic Resource
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    A tunable microwave frequency alternating current scanning tunneling microscope (1994)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 65 (1994), S. 918-921 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: By modulating the scanning tunneling microscope junction bias voltage at microwave frequencies, imaging and spectroscopy of insulating surfaces have become possible. In order to explore the spectroscopic capabilities of this instrument, we have developed a tunable microwave frequency alternating current scanning tunneling microscope. We combine the reliable beetle-style sample approach with coaxial sample and tip contacts. This provides us with a stable microwave-frequency-compatible scanning tunneling microscope. This alternating current scanning tunneling microscope design is compatible with ultrahigh vacuum and low-temperature operation.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1144921
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  • 112
    Electronic Resource
    Electronic Resource
    A new end-loss-ion energy analyzer with obliquely placed multigrids for open-ended plasma diagnostics (1994)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 65 (1994), S. 936-942 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: A new type of end-loss-ion energy analyzer (ELA; a multigridded Faraday cup) is applied to measure plasma ion temperatures Tip and plasma potentials ΦP in the GAMMA 10 tandem-mirror device. As compared with conventional-type ELA, this new ELA has obliquely placed ion- and secondary-electron-repeller grids and a collector plate with respect to external tandem-mirror magnetic fields. One of the most useful capabilities of this new ELA for precise ion measurements is to greatly reduce the current of high-energy electrons onto the collector plate. Also, this compact-sized ELA is scannable in the plasma to obtain radial profiles of Tip and ΦP without providing any perturbations of the tandem-mirror magnetic fields because it neither adds its own magnetic field nor needs to shield against the ambient magnetic field. Ion trajectories in the new ELA are numerically calculated so as to make a further understanding of its physics principles and to optimize its design. The energy-calibration experiments for the new ELA are carried out using ion beams; a fairly good agreement in the analyzed beam energies from the new ELA data and from conventional-type ELA data is attained. Furthermore, the first application of the new ELA to plasma diagnostics is made; a substantial reduction in energetic-electron influxes onto real ion signals makes a significant improvement in the analyses of Tip and ΦP.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1144923
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  • 113
    Electronic Resource
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    Temperature measurement in rapid thermal processing using acoustic techniques (1994)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 65 (1994), S. 974-976 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: Acoustic techniques are used to monitor the temperature of silicon wafers during rapid thermal processing from room temperature to 1000 °C with ±5 °C accuracy. Acoustic transducers are mounted at the bases of the quartz pins that hold up the silicon wafer during rapid thermal processing. An electrical pulse applied across a transducer generates an extensional mode acoustic wave guided by the quartz pins. The extensional mode is converted into Lamb waves in the silicon wafer which acts as a plate waveguide. The Lamb waves propagate across the length of the silicon wafer and are converted back into an extensional mode in the opposite pin. The time of flight of the extensional mode in the quartz pins is measured using pulse echo techniques and is subtracted from the total time of flight to obtain the Lamb wave time of flight across the wafer. Because the velocity of Lamb waves in the silicon wafer is systematically affected by temperature, the measurement of the time of flight of the Lamb wave provides the accurate temperature of the silicon wafer.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1144929
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  • 114
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    A system for in-situ pressure and ac susceptibility measurements using the diamond anvil cell: Tc(P) for HgBa2CuO4+δ (1994)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 65 (1994), S. 992-997 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: Substantial improvements have been made in the sensitivity of an ac susceptibility measurement system which determines the pressure dependence of the superconducting transition temperature, Tc(P). The pressure, P, is determined near Tc from the position of the R1 and R2 fluorescence peaks from ruby chips. The system was used to determine Tc(P) for several high Tc single crystals, but was not sufficiently sensitive to determine Tc(P) of polycrystalline samples for HgBa2CuO4+δ. This motivated us to improve the sensitivity of our system. Other parts of the system and the data analysis procedures also have been improved. As a demonstration, Tc(P) of HgBa2CuO4+δ polycrystal to 4 GPa is presented. The improvement of the system using the diamond anvil cell opens the possibility of measuring Tc above 10 GPa and on smaller samples.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1144878
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  • 115
    Electronic Resource
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    A new detection method used to calibrate Fabry–Perot interferometers in the infrared range (1994)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 65 (1994), S. 567-574 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: Fabry–Perot interferometers are routinely used in the Tore Supra tokamak in order to measure the time evolution of the electron temperature of the confined plasmas. Calibration of such interferometers requires the detection of very low dc levels (0.1 nV) with signal-to-noise ratios less than 10−5, which is generally not compatible with standard detection methods. A new correlation method is proposed to achieve this absolute calibration. It is based on a proper noise autocorrelation technique combined with an optimized filtering involving Fourier analysis. The advantages of the method are detailed and experimentally compared to standard averaging techniques, such as coherent addition and synchronous detection. The method can be used in a more general context every time very small amplitude signals are to be measured.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1145119
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  • 116
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    A laser-aided prealigned pinhole collimator for synchrotron x rays (1994)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 65 (1994), S. 597-602 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: A pinhole small-angle x-ray scattering (SAXS) instrument was constructed at the SUNY X3A2 beamline, National Synchrotron Light Source, Brookhaven National Laboratory. The three pinholes were mounted in a thick-walled stainless steel pipe and prealigned by using a portable laser source and a charge-coupled device (CCD) area detector. After the prealignment, incorporation of the collimator to the synchrotron x-ray source required only maximization of the incident x-ray intensity passing through the pinholes, which could be done easily by using a scintillation counter after proper attenuation. The entire synchrotron SAXS instrument setup took only a few hours even without stepping motor control for the pinhole collimator unit. By combining this collimator with a CCD-based x-ray area detector which could be assembled by using commercially available components, the SAXS instrument showed good performance for structural scales up to an order of 100 nm. The CCD-based x-ray area detector used a computer- (or manually) controlled intensified unit with a variable gain setting in order to accommodate the changing x-ray flux and to protect the detector from over exposure, a necessary feature for operation of an area detector at a synchrotron light source.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1145123
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  • 117
    Electronic Resource
    Electronic Resource
    Atomic force microscope with magnetic force modulation (1994)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 65 (1994), S. 639-643 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: We have constructed a scanned stylus atomic force microscope (AFM) with direct force modulation and integrated microfluorescence optics. The instrument was designed to image the surface of massive samples under various ambient conditions. In force modulation microscopy the imaging force is modulated during the scanning process via an external magnetic field that acts directly on the magnetic AFM tip. Polymeric Langmuir–Blodgett films on silicon oxide were imaged to evaluate the application range of the instrument. We demonstrate that direct force modulation microscopy permits the quantitative recording of the local complex compliance both as a function of the location and as a function of the frequency. In a novel imaging mode referred to as sample resonance mode, the contrast of the image can be selectively enhanced based on local elasticity differences.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1145130
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  • 118
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    Removal of the plasma contained in an atomic beam produced by electron beam heating (1994)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 65 (1994), S. 657-660 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: Removal of the plasma contained in a gadolinium atomic beam produced by electron beam heating was investigated. A positive or negative electric potential was applied to the plasma removal electrodes which were a pair of parallel electrodes put along the atomic beam. When a positive potential was applied to the plasma removal electrodes, the plasma could not be removed at high evaporation rates. On the other hand, the plasma could be removed by applying a high negative potential to both removal electrodes, even at high evaporation rates. The potentials applied to the electrodes required to remove the plasma were estimated using the model that a plasma at ground potential flows with the atomic beam; ions are extracted from the plasma by negatively biased removal electrodes. The estimated potentials required to remove the plasma agreed well with experimental values.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1145134
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  • 119
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    A modified ultrasonic interferometer for sound velocity measurements in molten metals and alloys (1994)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 65 (1994), S. 682-688 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: An ultrasonic interferometer has been developed for measuring compressional wave velocity (VP) and attenuation (or conversely, quality factor QP) in molten Fe, Fe-Ni, Fe-Ni-S, and Fe-Ni-Si alloys. Results for pure molten Fe are presented. A radio frequency (rf) induction technique is used for heating that allows a ±1 K temperature stability at 1973 K. The effects of the electromagnetic field interaction with the molten conductive metal are discussed in terms of applicability to VP and QP measurements. Considerations of acoustic impedance and thermal absorption are presented to discuss the high-temperature use of polycrystalline Al2O3 buffer rods for velocity and attenuation measurements. Viscoelastic theories, when applied to pure molten Fe, predict an extremely small acoustic coefficient of attenuation. Suggestions are made to circumvent the experimental difficulties encountered in attenuation measurements.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1145139
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  • 120
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    A laboratory EXAFS spectrometer in transmission dispersive mode (1994)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 65 (1994), S. 845-849 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: A laboratory spectrometer designed for routine extended x-ray absorption fine structure (EXAFS) measurements in dispersive mode is described. Factors determining energy range and resolution are detailed. An empirical energy calibration procedure is proposed. EXAFS spectra obtained for copper and zirconium metal foil and molecular complex ZrOCl2 compare favorably with data obtained using a conventional synchrotron facility.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1144909
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  • 121
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    PIN photodiode-based miniature gamma radiation detector for multiple applications including positron emission tomography radioisotopes (1994)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 65 (1994), S. 861-864 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: A method for using inexpensive PIN photodiodes for applications involving gamma radiation detection over several orders of magnitude in intensity is discussed. A description of the response characteristics of the PIN diode and its associated electronics is presented. Application of the detector to a radioactivity transporter, radioisotope delivery system, radiochemical processor, and radio-high pressure liquid chromatograph is discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1144912
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  • 122
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    Modified crossed-beam apparatus for charge-transfer cross section measurement (1994)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 65 (1994), S. 877-881 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: A modified crossed-beam apparatus to measure charge-transfer cross sections of metallic elements in wide impact-energy range (10–1000 eV) has been developed. The ion optics to extract charge-transferred ions from the primary neutral atomic beam was improved, and the background noise due to the collisions on residual gas and the charged particles produced by scattered laser light was reduced, and as the result, the S/N ratio of the charge-transferred ion signal was significantly improved to be (approximately-greater-than)100 at 10 eV impact energy. The reduction of primary ions extracted from the ion source in the atomic beam at low impact energy was compensated for by the improvement of the S/N ratio, and the impact energy for which the cross section can be measured was extended to a lower energy (∼10 eV).
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1144915
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  • 123
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    A simple two-axis ultraprecision actuator (1994)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 65 (1994), S. 910-917 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: This paper describes a highly controllable, short-range translation and rotation mechanism. Two solenoid-magnet force actuators are applied to a simple elastic mechanism resulting in separable translation and rotation drive axes. To provide design rules and assess potential error sources, a theoretical model is discussed and experimentally evaluated. Two such actuators using monolithic aluminum and single crystal silicon flexures have been constructed and measured using stylus-based, optical and x-ray interferometric techniques. They are used to demonstrate both longer range motions of 80 μm and 3.6 mrad and higher precision motions, with resolution of better than 0.6 nrad over ranges of around 10 μrad across 1 μm displacement. Performance of these devices was limited primarily by the available drive electronics and measurement techniques, so it is expected that even better precision can be achieved.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1144920
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    A precision, low-force balance and its application to atomic force microscope probe calibration (1994)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 65 (1994), S. 903-909 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: We present the design and evaluation of a novel precision balance consisting of a thin silica rod suspended on a beryllium copper spring flexure. At opposing ends of the rod are a capacitance sensor and a soleniod/magnet force actuator. When an external force is applied to the silica rod, the resultant deflection of the springs is detected and fed back through a servo controller and current amplifier to the force actuator, thus maintaining a null signal. Consequently, the coil current, which, for relatively small fields, can be considered proportional to its applied force, is monitored as the balance output. Three class I dead weight masses of 2, 5, and 100 mg were used for calibration with six less accurate weights used to verify the linearity of the balance to better than 1%. Using standard vibration isolation techniques and an inexpensive environmental chamber, the present design will measure loading forces up to 1 mN (100 mg) and it has a resolution of better than 70 nN Hz1/2 (7 μg Hz1/2). Presently measuring 40 mm in diameter and 40 mm height this compact design is constructed from low expansivity materials giving a thermal sensitivity of better than 0.03 μN K−1. Results from a calibration of an atomic force probe are also presented and discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1144919
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    Thin film microcalorimeter for heat capacity measurements from 1.5 to 800 K (1994)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 65 (1994), S. 946-959 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: A new microcalorimeter for measuring heat capacity of thin films in the range 1.5–800 K is described. Semiconductor processing techniques are used to create a device with an amorphous silicon nitride membrane as the sample substrate, a Pt thin film resistor for temperatures greater than 40 K, and either a thin film amorphous Nb–Si or a novel boron-doped polycrystalline silicon thermometer for lower temperatures. The addenda of the device, including substrate, is 4×10−6 J/K at room temperature and 2×10−9 J/K at 4.3 K, approximately two orders of magnitude less than any existing calorimeter used for measuring thin films. The device is capable of measuring the heat capacity of thin film samples as small as a few micrograms.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1144925
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    Digital frequency tripling circuit for third harmonic detection by lock-in amplifiers (1994)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 65 (1994), S. 971-973 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: A new digital circuit for fast and stable frequency tripling was constructed. The frequency tripler covers the input frequency range from 0.1 Hz up to 5 kHz with a maximum phase shift less than 1 deg at the highest frequency. The tripler generates a stable signal synchronized to the input after just one input period. Since the circuit design is flexible, input frequency range and phase accuracy can be improved using faster integrated circuits.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1144928
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    Computer models of wall–sensor interactions in measurements using zero-balance heat-flux meters (1994)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 65 (1994), S. 981-987 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: The principles of the zero-balance heat-flux meter (HFM) technique are studied with two steady-state finite difference computer models developed to simulate the responses of a sensor mounted either on the cold face or on the warm face of a wall. Computations show that a particular Biot number (defined by the authors), the dimensionless wall width, and the dimensionless wall thickness are the parameters affecting the HFM accuracy. The authors present outputs of their models that show the influence of these parameters, and propose three empirical expressions that allow corrections of the operational errors. It can be affirmed that the flux meter should be mounted on the cold face in the case of a small Biot number (it assures an accuracy of at least 5% if the Biot number value is smaller than 0.2). And it should be mounted on the warm face when the Biot number is large (in the case of building insulators in normal environment conditions it assures an accuracy of at least 10%). In other cases, the flux meter should be used as a gradient flux meter switching off the internal heater.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1144876
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    Magnetic manipulation instrumentation for medical physics research (1994)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 65 (1994), S. 533-562 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: The noncontact magnetic manipulation of probe masses within the body is an area of research that has received substantial attention from the medical physics community, especially during the past three decades. The therapeutic and diagnostic possibilities arising from such technology include site-specific drug delivery within the central nervous system, advancement of techniques for navigation and selective catheterization of vessels within the cardiovascular and cerebrovascular systems, and the nonsurgical exploration of the alimentary and respiratory tracts. In this review, we examine the physical principles underlying in vivo magnetic manipulation systems, and catalog the various types of instrumentation used for such purposes to date. Thereafter, we evaluate the different methods of image-based localization used to identify the position of the probe within the body. Finally, we appraise an emerging technology known as nonlinear magnetic stereotaxis, a technique that permits minimally invasive access to difficult-to-approach parts of the brain. We close the review with a few comments on the directions for future work within this field.
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    URL: http://dx.doi.org/10.1063/1.1145242
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    Deuterium pellet injector for speeds up to 3400 m/s (1994)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 65 (1994), S. 430-432 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: The injection of pellets of frozen deuterium into magnetically confined, hot plasmas is one of the most attractive methods for refueling fusion power reactors. High injection speeds for solid deuterium pellets are necessary for improving the experimental analysis of pellet ablation in a hot plasma and the effects of the pellet on the plasma properties, in particular the confinement parameters. The optimization of a two-stage light gas gun is being pursued; the search for the cryogenic conditions of freezing deuterium with good mechanical properties is carried out. In particular, the impurities concentration in deuterium during the condensation process has been studied. These developments have allowed one to reach velocities up to 3400 m/s for integer bare deuterium pellets (3 or 4 mm in diameter, 1–3×1021 particles) with a reliability of 80%.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1145151
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    Radio-frequency power combiner for cw and pulsed applications (1994)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 65 (1994), S. 449-452 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: We describe the design and operation of a circuit to combine the output signals of two high-power radio transmitters into a single load. A working unit is realized using a commonly available ferrite and cheap coaxial cables. Performance tests indicate satisfactory operation from 3 to 50 MHz with less than 1 dB total power loss while guaranteeing adequate isolation between the transmitters. The power combiner can also be constructed specifically to withstand high line voltages for short time periods thus making it suitable for high-power pulsed applications such as plasma formation and heating.
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    URL: http://dx.doi.org/10.1063/1.1145155
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    Aero-acoustic levitation: A method for containerless liquid-phase processing at high temperatures (1994)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 65 (1994), S. 456-465 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: A method for containerless liquid-phase processing was developed which has practical application in process and property research on virtually any material which is involatile at the melting point. It combines aerodynamic and acoustic forces to support and position the levitated material. The design provides forced convection control of the thermal boundary in the gas surrounding beam-heated specimens, which stabilizes the acoustic forces and allows acoustic positioning necessary to stabilize the aerodynamic levitation forces on molten materials. Beam heating and melting at very high temperatures was achieved. Experiments were conducted on specimens with diameters in the range 0.25–0.4 cm, of density up to 9 g/cm3, at temperatures up to 2700 K, and in oxygen, air, or argon atmospheres. Unique liquid-phase processing results included deep undercooling of aluminum oxide, glass formation at exceptionally small cooling rates, complete melting and undercooling of YBa2Cu3Ox superconductor materials, direct formation of the YBa2Cu3Ox from the liquid phase, and the vaporization of volatile constituents from a low-liquefaction point glass to form a refractory, high melting material. The application of rapid containerless batch processing operations to materials synthesis is discussed.
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    URL: http://dx.doi.org/10.1063/1.1145157
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    Micro-Pirani vacuum gauge (1994)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 65 (1994), S. 492-499 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: A Pirani vacuum sensor has been fabricated by the silicon micromachining technique. A square glass membrane was formed on (100) silicon substrate with a platinum-film resistor coated. The membrane is suspended by its four leads extended to the corners of an etched cavity. This structure can provide both low thermal loss through leads to the substrate and large active area for gaseous heat conduction. It thus can be used as a highly sensitive vacuum sensor. The fabricated sensor has shown a linear response of pressure from 8×10−5 to 6 Torr with constant-temperature operation. It is found that the low-pressure limit of the vacuum sensor was caused by the noise of the instrument used in the experiment. A new terminology called "noise equivalent pressure'' thus is definable due to this finding. The physical limit of the noise equivalent pressure is analyzed. Optimization of the device structure and the noise equivalent pressure are also discussed in detail. A new method of ambient-temperature compensation is also proposed and analyzed here.
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    URL: http://dx.doi.org/10.1063/1.1145163
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    Twin-horseshoe resonator—An investigation (1994)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 65 (1994), S. 509-510 
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    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: Two parallel-plate copper rings with diagonally opposite gaps separated by a dielectric medium form a resonator the natural resonant frequency which is a function of the transmission line propagation constant, its characteristic impedance, as well as the series inductance of the two loops. By means of an extra capacitor connected to each gap, one can easily vary the frequency of the resonator. The derived expressions, valid also for coaxial line devices, relating resonant frequency to other circuit constants, can serve as a tool for those who intend to use this kind of resonator to design NMR surface coil antennas. Experimental results are in good agreement with theory provided the circuit constants are accurately known.
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    URL: http://dx.doi.org/10.1063/1.1145244
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    Fast averaging data acquisition unit for pulse spectrometers (1994)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 65 (1994), S. 517-518 
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    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: A combined pulse generator and digitizer based on a RISC processor has been designed and tested by 59Co NMR. The pulse generator provides a 16-bit TTL-level output with 100 ns resolution and is programmable in the high-level language FORTH. The digitizer supports two channels, each with a 10 bit, 40 MSPS analog-digital converter and online averaging in a 24×1024 bit memory, which is directly accessible by the RISC processor.
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    URL: http://dx.doi.org/10.1063/1.1145116
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    Controllable pulse duration of a XeCl laser (1994)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 65 (1994), S. 3634-3638 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: Long optical pulses have been generated in a XeCl excimer laser by using a simple capacitor-transfer discharge circuit consisting of storage capacitors charged at 26 kV and discharged through the electrodes, tightly coupled to the variable small peaking capacitors. By adjusting the [HCl] concentration and capacitance ratios, the typical pulse duration (20 ns) is stretched up to 150 ns (full width at half-maximum). The transfer behaviors of the pulse duration from short pulse to long pulse are presented and analyzed extensively by measuring the discharge voltage profile, output energy, overall efficiency, optical waveform, and pulse duration, as functions of [HCl] concentration and capacitance ratios. © 1994 American Institute of Physics.
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    URL: http://dx.doi.org/10.1063/1.1144484
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    A low-temperature total electron yield detector for x-ray absorption fine structure spectra (1994)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 65 (1994), S. 3667-3669 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: A design of a total electron yield detector to collect x-ray absorption fine structure spectra between 80 K and room temperature is described. In addition, a three-stage goniometer setup has been incorporated into the detector to facilitate manipulation of the sample. The results of simple linearity checks to investigate the detector's electrical performance are presented. Finally, the detector's thermal stability is discussed. © 1994 American Institute of Physics.
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    URL: http://dx.doi.org/10.1063/1.1144489
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    One-dimensional scanning of moisture in porous materials with NMR (1994)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 65 (1994), S. 3673-3681 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: A versatile and modular nuclear magnetic resonance (NMR) instrument is described that is particularly suited for the study of moisture transport in porous media such as various building materials in which moisture can give rise to several kinds of damages. Quantitative measurements of one-dimensional moisture profiles and their time evolution can be performed on cylindrical samples having a diameter up to 20 mm with a spatial resolution better than 1 mm. Water absorption and drying experiments on various building materials demonstrate that the instrument can also be used for materials containing relatively large amounts of magnetic impurities, which until now were hardly accessible by NMR techniques. © 1994 American Institute of Physics.
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    URL: http://dx.doi.org/10.1063/1.1144491
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    Improved differential heterodyne interferometer for atomic force microscopy (1994)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 65 (1994), S. 3697-3701 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: A highly sensitive displacement sensor for atomic force microscopy is described which enables one to measure the relative displacement of the tip from a sample surface. The sensor is based on the differential heterodyne interferometer formed between the reflections from the microscope cantilever backside and the sample surface. As a result of using an optical common-path construction, the sensor is essentially insensitive to the mechanical vibration, and achieves high stability at low frequencies, even though there are certain restrictions imposed by the reflection from the examined surface and the variable deflection mode. Images are presented demonstrating the atomic resolution of mica and graphite. © 1994 American Institute of Physics.
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    URL: http://dx.doi.org/10.1063/1.1144494
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    Analysis of the properties of an electrostatic triplet quadrupole lens used as an electron beam transport device (1994)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 65 (1994), S. 3718-3723 
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    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: The electron optical properties of an electrostatic triplet quadrupole lens used as an electron beam transport device were reexamined, both analytically and by computer simulation, in order to derive limits on the choice of the design parameters of the lens. Furthermore, computer simulation of electron trajectories through a single quadrupole lens, and comparison with experimental results obtained by other authors, have led to a graphical relation between the fringing field end correction and the aspect ratio of the lens. © 1994 American Institute of Physics.
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    URL: http://dx.doi.org/10.1063/1.1144497
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    Beam-centroid tracking instrument for ion thrusters (1994)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 65 (1994), S. 3733-3738 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: Thrust vector stability for an electrostatic ion engine can be measured with improved sensitivity and time resolution by the method described here. Four double-wire Langmuir probes, aligned in the form of a cross, are placed in the exhaust plume and are translated by a motorized positioning system to balance the currents collected along two orthogonal axes. The thrust vector position is thereby measured with an angular resolution of 〈0.01° and a response time of 〈5 s. © 1994 American Institute of Physics.
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    URL: http://dx.doi.org/10.1063/1.1144499
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    Luminescent thermometry for aerodynamic measurements (1994)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 65 (1994), S. 712-720 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: A luminescent temperature sensitive paint containing the molecule rhodamine B base in a silicone polymer paint has been developed that utilizes video imaging detection to produce temperature maps of an entire surface from luminescence intensity measurements. The luminescent thermometry system has been calibrated in the laboratory to have an intensity loss of 2.30% per °C, in the range of 10 to 46 °C, with a root mean square prediction error (RMSPE) of 0.26 °C. To evaluate the technique, transient temperature field measurements have been made on a copper plate with a heater at one end. In spite of a loss in sensitivity of the paint due to aging effects that reduced sensitivity to 1.39% intensity loss per °C, the calculated RMSPE was 0.25 °C and the time series of temperature profiles predicted from luminescence agree with those predicted by a numerical solution to the heat flow equation. Data was also collected from the surface of an airfoil in a wind tunnel experiment. In spite of systematic temperature differences between the thermocouples used for calibration and the paint, RMSPE's of less than 1 °C were obtained.
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    An application of a thermosensitive quartz resonator for liquid flow rate measurement (1994)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 65 (1994), S. 721-723 
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    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: The temperature-frequency dependence of a thermosensitive quartz resonator is used for the measurement of liquid flow rate. Because of a special quartz cut the resonator has very high temperature sensitivity which allows very small temperature changes to be detected. Using a heater the resonator is heated to a temperature higher than the ambient temperature. The resonator and the heater are designed together as a measuring probe which is placed in the path of a flowing liquid. The liquid flow cools the resonator and causes a frequency change. Using another resonator the temperature difference between the temperatures of the heated resonator and the ambient liquid is measured. In a number of experiments the relationship between the resonator temperature and water flow rate is investigated. A theoretical analysis for this relationship is delivered too. It is found that when the water flow rate is varied from 0.1 to 1.4 m/s the resonator temperature changes within 15 °C.
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    URL: http://dx.doi.org/10.1063/1.1145091
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    Forming of high-voltage nanosecond and subnanosecond pulses using standard power rectifying diodes (1994)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 65 (1994), S. 751-753 
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    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: A new simple circuit for producing high-voltage nano- and subnanosecond pulses at high repetition rates is presented. Output peak voltages and rise times are 6 kV, 2 ns or 8 kV, 0.1 ns. Only standard commercial components are employed. Diode parameters that limit achievable voltage levels have been studied.
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    URL: http://dx.doi.org/10.1063/1.1145241
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    A method to reduce sensor bridge dependence on loading and excitation voltage (1994)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 65 (1994), S. 756-757 
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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 sensor bridge circuits readout dependence on loading, introduced by the meter and/or amplifier, and on eventual variations on excitation voltage is described. Experimental results on simulated strain gages and thermistors bridges, where both power and signal have been coupled directly using transformers (relatively low load impedances), are also reported.
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    URL: http://dx.doi.org/10.1063/1.1145098
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    Comment on "A new powder diffraction method for linear detectors'' [Rev. Sci. Instrum. 64, 2201 (1993)] (1994)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 65 (1994), S. 764-764 
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    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: In this comment, the authors acknowledge that at the time of publication of their article, they were not aware of the independence of discovery by Megtert et al.1,2 of the powder diffraction technique; hence they did not include Megtert et al.'s reference in their original article. (AIP)
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    Parametric study of an x-ray preionizer with plasma cathode (1994)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 65 (1994), S. 315-322 
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    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: The construction characteristics and the performances of an x-ray diode working at 200 Hz are described. The temporal behavior of both the plasma cathode emission and the diode discharge has been studied, including the measurements of vacuum effects on the repetition rate and lifetime capability, preionization versus electrical features, and ionization density versus dosage. This simple and low-cost x-ray diode has been used to uniformly preionize a half-liter XeCl laser, delivering an output laser energy of 800 mJ/shot at a 100 Hz repetition rate.
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    URL: http://dx.doi.org/10.1063/1.1145190
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    Grazing angle x-ray photoemission system for depth-dependent analysis (1994)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 65 (1994), S. 339-342 
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    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: We have developed an x-ray photoelectron spectrometer system which combines an adjustable grazing incidence angle source with reflected beam detection. When operated about the critical angle, this combination permits a variation of the x-ray penetration depth which can be monitored by means of the reflectivity. At angles of incidence less than the critical angle, the sampling depth of the photoemission is diminished, but the photoemission from the surface is enhanced due to the constructive interference of the incident and reflected x-ray beams. When used with Mg Kα radiation (Eγ=1253.6 eV), the spectrometry system obtains useful distributions of chemical species in surface layers of 10–40 A(ring) thickness. We present data showing the depth dependence obtained with the spectrometer of different oxides in a sulfide-treated, oxidized GaAs (100) surface.
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    URL: http://dx.doi.org/10.1063/1.1145193
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    A powerful eyesafe infrared aerosol lidar: Application of stimulated Raman backscattering of 1.06 μm radiation (1994)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 65 (1994), S. 3324-3331 
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    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: A powerful infrared aerosol lidar operating at the eyesafe wavelength of 1.56 μm has been developed. More than 140 mJ per pulse are obtained from stimulated Raman backscattering narrow-band Nd:YAG laser radiation in deuterium. The mobile lidar system was successfully applied during the VAST and MAPTIP international aerosol field campaigns in 1992 and 1993. A range between 0.3 and more than 10 km is demonstrated for slant-path measurements in the presence of aerosols or cirrus clouds.
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    URL: http://dx.doi.org/10.1063/1.1144569
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    A new continuum-source atomic absorption spectrometer (1994)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 65 (1994), S. 3339-3343 
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    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: Metallic toxics such as mercury, lead, cadmium, manganese, and other species are now of particular importance in relationship to coal-based utilities, waste-to-energy plants, medical waste incinerators, and other industrial sources of atmospheric emissions or residues deposited in landfills. These metals are strong emitters or absorbers of middle ultraviolet light in the same general spectral region where important molecular pollutants are active. The furnace system of a commercial atomic absorption spectrometer, a continuum ultraviolet light source (a deuterium arc), and an oscillating entrance slit (adapted from second derivative spectroscopy) are applied to the measurement of toxic metals. The second-harmonic ripple in the output of the photomultiplier tube is amplified by use of a tuned amplifier. A large signal-to-noise improvement is achieved when this system is calibrated and optimized with the metallic species of interest. This approximately compensates for the selectivity loss in using a continuum source in place of special lamps. Employment of this system is described in detail for the detection of mercury and the results are given for eight metals (Hg, Cd, Mn, Zn, Pb, Ni, Cu, and Cr). Data scatter when using this second-harmonic spectrometer system is roughly 1/10 that of standard procedures.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1144570
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    Impedance-matching anode for fast timing signals (1994)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 65 (1994), S. 871-876 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: In this article a novel design for signal anodes for ultrafast microchannel plate detectors is introduced. A detector assembly was designed and built with an impedance-matched transition line (50 Ω line resistance) from anode to cable connector which is considerably smaller than other, commercially available, solutions and at the same time has about four times the active area with no limitations for up scaling to even larger active areas. Theoretical proof is given that the impedance matching can be achieved over the entire transition line. The design makes use of a bipolar geometry and is flexible to accommodate differing experimental needs. The design was chosen to optimize for small overall size with good temporal response at the same time. The detector was tested with an alpha particle source and an excellent time response was obtained. Although the design was driven by special needs for space application the detector can be applied wherever short timing pulses are needed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1144914
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  • 151
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    A metrological constant force stylus profiler (1994)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 65 (1994), S. 892-902 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: A second-generation constant force profiler is described combining a capacitance based stylus force probe with interferometric optical metrology to monitor position of the specimen carriage. The probe has a vertical range of 15 μm with a resolution of 0.23 nm and a flat bandwidth response with a −3 dB cutoff at 228 Hz. Passing the output signal through a single pole 200 Hz low-pass filter, an overall system peak-to-peak broadband noise of less than 5 nm is observed. Manufactured primarily from inexpensive materials, the instrument demonstrates a stability of around 1 nm min−1 under controlled laboratory conditions. Using an inexpensive motor/gearbox/micrometer open-loop drive with velocity variations of up to 20%, profiles showing nanometer repeatability over 15 mm traces are demonstrated. Also shown is a profile of a soft contact lens in the hydrated state. The effect of the contact stiffness on the stylus probe/specimen interaction is illustrated by examining the dynamics of the force probe system while operating in the repulsive mode.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1144918
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    A new image processing method for extracting integrated intensities from low-energy electron diffraction spots (1994)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 65 (1994), S. 3382-3388 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: We have devised and programmed a new scheme based on image processing techniques for extracting the intensity of fluorescent display low-energy electron diffraction spots. The method make no assumptions about spot shape, does not use thresholding, and can deal with badly behaved backgrounds, noise spikes, and dead pixels. All decisions about whether a particular pixel belongs to a spot or to the background are made on purely logical grounds with generally binary operator masks. Once the spot edge has been defined, a local background is subtracted to generate an integrated spot intensity. Extensive tests with diffraction features ranging from very strong to indistinguishable from background by eye show this method to be stable, fast, and reproducible.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1144577
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  • 153
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    Space-resolving flat-field vacuum ultraviolet spectrograph for plasma diagnostics (1994)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 65 (1994), S. 3408-3414 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: A spatial imaging vacuum ultraviolet (VUV) spectrograph has been constructed for simultaneous observation of spatial and spectral distributions of plasma radiation in the wavelength range 150–1050 A(ring). The spectrograph consists of an entrance slit of limited height which provides spatial resolution, an aberration-corrected concave grating with varied spacing grooves which gives a flat-field spectral output plane, and an image-intensified two-dimensional detector system. The basic characteristics of the spectrograph have been investigated by ray-tracing calculations. The expected performance has been confirmed through experiments using a dc glow discharge source on the reciprocal dispersion, the spatial resolution, or the incident angle dependence of spectral images. VUV spectra with spatial and time resolution have been obtained successfully in the GAMMA10 tandem mirror experiment.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1144514
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    Development of a real time visualization system for the shape of a tokamak plasma cross section (1994)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 65 (1994), S. 3434-3438 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: A real time visualization system for the shape of a tokamak plasma cross section has been developed by using Versa Module Europebus (VME)-standardized modules. Digital signal processors (DSPs) are used in parallel for magnetic analysis. A fast and high resolution graphics control processor is adopted for part of the display system. Fast shape identification methods are presented in which tabulated Green's functions are utilized. The analysis errors are evaluated with Hitachi tokamak 2 (HT-2) experimental data. The plasma shape is visualized in real time with the cycle time of 30 ms. When this system is applied to the International Thermonuclear Experimental Reactor (ITER), the estimated cycle time for visualizing the plasma shape is 40 ms.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1144518
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    Beam diagnostics with localized space-charge waves (1994)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 65 (1994), S. 3444-3448 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: A new method for the diagnostics of charged particle beams by employing localized space-charge waves is presented. The propagation of space-charge waves in the form of localized perturbations can be measured easily and accurately in experiments. The results carry valuable information about many beam parameters such as the wave speed, the geometry factor g for the longitudinal space-charge field, the beam radius, the beam impedance under longitudinal perturbations, etc. The principle of this technique and an experimental example are given in this article.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1144520
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    High efficiency molecular-beam ionization detector with short ionization region (1994)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 65 (1994), S. 3458-3465 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: A mass selective electron-impact ionization detector for use in energy resolved thermal He scattering experiments is presented. The detector combines a short effective ionization region (approximately 3 mm FWHM) with a high detection efficiency of 10−5 at 2 mA electron emission. An efficiency of 10−4 at 10 mA emission current can be achieved if time resolution below 20 μs is dispensable. The design is discussed and measurements of detection efficiency and time resolution are presented. The ionizer can likewise be employed for an efficient detection of other types of atoms or molecules.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1144523
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    Determination of material properties by using the reflection pulse method (1994)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 65 (1994), S. 3505-3510 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: New methods based on the reflection pulse technique are developed to study material properties. Using them, Curie temperatures in magnetic and ferroelectric materials, transition temperature and penetration depth in superconductors and characteristics of semiconductors, and semiconductor devices are determined.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1144529
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    Depolarized Rayleigh scattering of polymeric materials and their oligomers: Instrument design, calibration, and data analysis issues (1994)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 65 (1994), S. 3511-3516 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: The importance of obtaining dependable values of molecular optical polarizability anisotropy for polymers and their oligomers lies in their subsequent use in the rotational isomeric state theory and in calculations involving the components of the optical polarizability tensor. This work describes a depolarized Rayleigh scattering photometer able to determine optical polarizability anisotropy of oligomers, melts, and polymer compounds in solution with a combination of exceptional accuracy and high sensitivity. Two separate calibration techniques are reported that ensure the accuracy and preciseness of the results obtained from the measurements. Finally, data analysis procedures are reported that show the sensitivity of the results to the internal field correction.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1144530
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    Thermal response of CMOS-micromachined thermistor sensors under constant power and constant current excitation (1994)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 65 (1994), S. 3528-3534 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: The resistance of a micromachined polysilicon thermistor sensor has been measured under excitation by both a constant current and constant power step. The time-varying and steady-state response of the polysilicon resistor at ambient pressures of 1 atm and 10−4 Torr were observed under various step amplitudes. The increase of resistance above its room-temperature value changed exponentially with time; the time constant varied inversely with the square of the current step amplitude but was constant with power step amplitude. The steady-state change of resistance varied linearly with the applied power under both modes of excitation. The time-varying and steady-state responses were as predicted by a simple analytic model developed. The steady-state operation of these devices at the two pressures permitted us to directly determine the energy losses by heat conduction through the surrounding gas and conduction through the support arms. At 1 atm, up to 90% of the heat loss is by conduction through the gas. The operation of the device was also simulated numerically and results were obtained in reasonably close agreement with experiment. The simulation also allows us to predict the amount of heat flow through the various support arms; 70% of the heat conducted by the support arms flows through 8 of the 20 support arms.
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    URL: http://dx.doi.org/10.1063/1.1144533
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    An automatic apparatus for measuring interfacial and film tension under static and dynamic conditions (1994)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 65 (1994), S. 3555-3562 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: A fully automated and computer controlled apparatus is described that measures the interfacial tension (IFT) of fluid interfaces and the film tension of liquid films. The fluid interface is formed as a nearly spherical drop at the tip of a capillary which is immersed into another immiscible fluid. The size of the interface is controlled and measured by controlling the size of the drop and the capillary pressure is monitored by a sensitive pressure transducer. The interfacial tension is calculated by the Young–Laplace equation. The drop at the capillary tip can also be covered with a cap shaped liquid film and then the film area can be controlled and the film tension measured. This apparatus is useful for measuring equilibrium interfacial tension or film tension, the adsorption kinetics by stress relaxation experiment and the dynamic interfacial tension or dynamic film tension under both interface expansion or contraction conditions. The capabilities of this versatile, automatic instrument are illustrated with typical experimental results.
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    URL: http://dx.doi.org/10.1063/1.1145203
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    Low-temperature two-axis goniometer with accurate temperature control (1994)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 65 (1994), S. 3574-3576 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: We have designed a probe to rotate a sample around two independent axes in a magnetic field of up to 8 T and at temperatures varying from 3 K to room temperature. The sample is in very good thermal contact with a thermometer and a regulated heater, enabling precise temperature control. Pogo pins enable quick electrical connections to the sample. Two computer-controlled stepper motors rotate the sample around the two independent axes. This probe was primarily designed to investigate the anisotropy of the critical currents of superconducting thin films in a magnetic field.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1144539
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    A high-speed wide dynamic range time-to-digital converter (1994)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 65 (1994), S. 3577-3584 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: We describe a time-to-digital converter able to measure intervals as great as 100 ns with a resolution of 4 ps rms. It achieves this large dynamic range by simultaneously sampling four sinusoidal wave forms (sine and cosine waves at 200 and 6.25 MHz) derived from a single quartz oscillator. Twelve-bit analog-to-digital conversion of the 200 MHz waves yields the high time resolution. Eight-bit conversion of the 6.25 MHz samples removes the cycle ambiguity of the 200 MHz data. The digital words are pipelined in a fully parallel data flow architecture. A first-in first-out stage in the pipeline derandomizes the random event arrival times. A subsequent stage in the pipeline uses an arctangent function to convert the sine and cosine pairs into linearized measures of event time. These are subtracted to yield start–stop time interval sizes for individual photoevents. The minimum start–stop interval is 50 ns, set primarily by the cycle time. Because the same processing is employed for the start and stop events, a large class of potential error and drift phenomena are eliminated. The digitizer provides an accurate way to decode the outputs of delay line detectors, offering high event throughput and extremely good long-term timing accuracy. As a side benefit, the pipeline data flow architecture permits simple breadboarding and low-throughput testing of the system stages with the arctangent work implemented in a personal computer. This arrangement is also very convenient for logging diagnostic evaluation data. The same front-end and data flow architecture is directly applicable to very high-speed applications where the event processing is implemented in a digital signal processor.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1144540
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    Derivation of the effective E field for short electromagnetic pulses (1994)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 65 (1994), S. 3592-3593 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: As the time duration of an electromagnetic pulse becomes shorter the bandwidth of the pulse increases. This presents a problem in the selection of a frequency for the calculation of the effective E field. This paper discusses a method for calculating the effective E field of a short electromagnetic pulse.
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    URL: http://dx.doi.org/10.1063/1.1144480
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    Metal vapor vacuum arc ion source research at Ansto (1994)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 65 (1994), S. 3082-3087 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: Following the pioneering work on metal vapor vacuum arc (MEVVA) ion sources at Lawrence Berkeley Laboratory by Brown and co-workers, the Australian Nuclear Science and Technology Organization (Ansto) commenced a program of research aimed at constructing a MEVVA based ion implanter. This phase of the program has been completed and the system is now in routine use for surface modification studies. The purpose of the present article is to give an overview of the Ansto implanter with particular reference to those features, such as triggering reliability, which entailed some developmental work. Finally, current ion implantation research activities on this system are briefly described.
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    URL: http://dx.doi.org/10.1063/1.1144757
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    Vacuum arc bismuth ion source with film cathode (1994)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 65 (1994), S. 3099-3100 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: A new variant of vacuum arc ion source is described whereby the problems of short cathode lifetime and low charge states, commonly found for low boiling point cathode materials, are avoided. This novel source embodiment has been operated using bismuth as the wanted ionic species. It was found that the ion charge state spectrum can be improved (i.e., increased) significantly, with the charge state of maximum amplitude being increased from Bi1+ to Bi3+, and the number of pulses that were obtained before the cathode needed changing was 108.
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    URL: http://dx.doi.org/10.1063/1.1144760
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    Ion beam noise reduction method for the MEVVA ion sourcea) (1994)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 65 (1994), S. 3109-3112 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: The beam extracted from the MEVVA ion source tends to be of a relatively high noise level, particularly for the higher charge states, making beam transport difficult in accelerator application. This paper presents experimental results which show that the use of grids within the ion source in combination with a solenoidal magnetic field can decrease the noise of the extracted beam considerably. The noise reduction can be explained by an increase in plasma density due to the applied magnetic field and space charge limitation of the extracted ion beam current.
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    URL: http://dx.doi.org/10.1063/1.1144763
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    Fluoride salts as supersonic nozzle materials for hot fluorine (1994)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 65 (1994), S. 3587-3588 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: An intense supersonic beam of atomic fluorine has been generated using nozzles fabricated from single-crystal CaF2 and MgF2. The latter material has been tested up to 1000 °C with no observable damage. This is (approximately-greater-than)250 °C hotter than previously achieved, increasing the atomic beam intensity by (approximately-greater-than)5×.
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    URL: http://dx.doi.org/10.1063/1.1144542
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    High repetition rate operation of a rotating dielectric spark gap (1994)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 65 (1994), S. 3590-3591 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: The reliable operation of a spark gap at 300 Hz pulse repetition frequency by rotating a suitably configured dielectric plate between its electrodes is reported. The triggering of the spark gap has been achieved by the use of an optical sensor.
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    URL: http://dx.doi.org/10.1063/1.1144544
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    Vacuum arc ion sources (1994)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 65 (1994), S. 3061-3081 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: The vacuum arc is a rich source of highly ionized metal plasma that can be used to make a high current metal ion source. Vacuum arc ion sources have been developed for a range of applications including ion implantation for materials surface modification, particle accelerator injection for fundamental nuclear physics research, and other fundamental and applied purposes. The beam parameters can be attractive, and the source has provided a valuable addition to the spectrum of ion sources available to the experimenter. Beams have been produced from over 50 of the solid metals of the periodic table, with mean ion energy up to several hundred keV and with beam current up to several amperes. Typically the source is repetitively pulsed with pulse length of order a millisecond and duty cycle of order 1%, and operation of a dc embodiment has been demonstrated. Here the source fundamentals and operation are reviewed, the source and beam characteristics summarized, and some applications examined.
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    URL: http://dx.doi.org/10.1063/1.1144756
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    Investigation of MEVVA ion source for metal ion injection into accelerators at GSI (1994)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 65 (1994), S. 3091-3098 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: High current metal ion production is a challenging task for ion source designers. The MEVVA ion source has proven to be a useful tool for accelerator injection and for ion implantation. We have investigated the MEVVA ion source in connection with the GSI heavy ion accelerators. At the Unilac accelerator as injector for the heavy ion Synchrotron SIS (1 Hz and 100 μs pulse length) the MEVVA can deliver mA beams of multiply charged ions up to 3+ (or mass to charge ratio of ≤24 accepted by Unilac). At the 300 kV ion implantation facility the MEVVA is used to inject metal ions into the RFQ accelerator with duty cycles above 1%. Here we discuss the ion beam currents and charge state distributions for various ion species and beam formation and transport at the accelerators. Space-charge effects and ion beam instabilities are discussed in detail. At the Unilac injector results with titanium and nickel from the MEVVA ion source are compared with those of neon from a CHORDIS gas ion source.
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    URL: http://dx.doi.org/10.1063/1.1144759
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    Vacuum arc ion source for the ITEP RFQ accelerator (1994)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 65 (1994), S. 3104-3108 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: A version of vacuum arc ion source has been developed and constructed at the Institute for Theoretical and Experimental Physics, Moscow, for use with a heavy ion radio frequency quadrupole linac. The source is operated in a pulsed mode with a pulse length from 5 to 120 μs and a repetition rate of from 1/8 to 1 pps. The injection voltage is up to 90 kV depending on the kind of ions being used, and the beam current at the injector output is up to 500 mA. The results described in this article were made at a beam current of from 10 to 100 mA. In order to obtain ions having a charge-to-mass ratio of about 1/60, metals such as Cu, Mo, Ta, W, and Pb were used as the cathode material. Volt-ampere characteristics and charge state distributions were measured. The charge state spectral variation was investigated throughout the arc current pulse duration as well as the dependence of the mean charge state of the beam ions on the melting point of the cathode material.
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    URL: http://dx.doi.org/10.1063/1.1144762
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    Cryogenic bolometric radiometer and telescope (1994)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 65 (1994), S. 301-308 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: The design and performance of an instrument to measure cosmic microwave background (CMB) anisotropy on angular scales from 10' to 30' is reported. The instrument utilizes a single-mode waveguide bolometer cooled by an adiabatic demagnetization refrigerator. This is the first time a 100 mK bolometer has been used in a CMB experiment. Observations of the CMB were made using this radiometer from the South Pole during the 1991–1992 season and, with minor modifications, during the 1992–1993 season. The radiometer is used with a fully steerable altitude-azimuth Cassegrain telescope built for this observation, also described here.
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    URL: http://dx.doi.org/10.1063/1.1145188
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    Design review of an instrument for spectroscopic total integrated light scattering measurements in the visible wavelength region (1994)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 65 (1994), S. 327-334 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: A spectroscopic total integrated scattering instrument, which uses a focusing sphere and a broadband light source, has been constructed. It records total reflectance and transmittance spectroscopically, in the wavelength region 400–1000 nm. Diffuse reflectance and transmittance values below 10−4 can be registered. These measurements require low scattering optical components and low noise electronics. Design details are given about the detection system, particularly the low noise preamplifier. The purpose of the instrument is to measure diffuse reflectance and transmittance spectra of interference coatings. Such spectra can give information about the amplitude of the roughness of the interfaces and reveal if the interfaces are topographically correlated or uncorrelated. Examples of spectra in both reflectance and transmittance mode are given.
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    URL: http://dx.doi.org/10.1063/1.1145191
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    High-pressure quasielastic and static light scattering apparatus (1994)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 65 (1994), S. 335-338 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: We describe an apparatus for multiangle light scattering studies of samples that are under hydrostatic pressures. The mean hydrodynamic radius and mean radius of gyration can be determined using quasielastic and static light scattering at temperatures between 5 and 85 °C and pressures between 0.1 and 100 MPa.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1145192
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    Scanning tunneling microscope combined with scanning electron microscope for the study of grain boundaries (1994)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 65 (1994), S. 3199-3203 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: An instrument that incorporates a scanning electron microscope (SEM) and a scanning tunneling microscope (STM) in an ultrahigh vacuum environment was designed to address the specific difficulties of imaging heterogeneous surfaces. A sample may be mounted in the STM for simultaneous STM and SEM imaging, or transferred to a manipulator where other surface analytical tools may be utilized. The STM is based on a viton-stainless-steel stack design and the SEM employs a 5 kV, electrostatic-lens electron gun. The sample mount is fixed, while the tip can be positioned in three orthogonal directions. Macroscopic positioning of the tip is accomplished using two orthogonal linear piezoelectric "inchworm'' motors and a stepper motor, whereas microscopic positioning is accomplished with a piezoelectric tube scanner
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1144550
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    Analog ramp generator for a fast scanning tunneling microscope (1994)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 65 (1994), S. 3220-3223 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: We present an analog ramp generator for use in fast scanning tunneling or scanning probe microscopes. The analog design achieves low noise with a relatively simple circuit layout. The circuit requires minimal computer overhead because the X and Y ramps are generated using just two clocks and one digital control line. The resulting X and Y ramps are automatically set equal in magnitude, yielding images which remain square despite changes in scan size, number of lines per image, and tip velocity. We have used the circuit at X ramp frequencies above 10 kHz.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1144553
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    Plane grating monochromator beamline for VUV radiometry (1994)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 65 (1994), S. 3229-3232 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: A new beamline for radiometric applications (e.g., detector calibration and reflectometry) has been installed and characterized at the laboratory of the Physikalisch-Technische Bundesanstalt at the electron storage ring BESSY. The beamline is equipped with a SX700 type plane grating monochromator and a toroidal mirror behind the exit slit of the monochromator for collimating the radiation to allow angle resolved reflectometry. A divergence of 0.1 mrad has been achieved. The beamline has been optimized for high spectral purity of the radiation. Within the photon energy range from 40 to about 1500 eV the total amount of stray light and higher order radiation stays below 1%. A photon flux of up to 1011 s−1 has been measured in the focal point of the toroidal mirror. It corresponds to a radiant power of a few μW and thus allows use of a cryogenic radiometer for detector calibration. The details of the beamline layout and the results of the performance characterization are presented.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1144555
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  • 178
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    Two wire thermocouple: Frequency response in constant flow (1994)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 65 (1994), S. 3252-3257 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: Experimental measurements are made with a novel two wire thermocouple. Signals from two wires of unequal diameters are recorded from the thermocouple suspended in constant flow with a periodic temperature fluctuation. It is demonstrated that the reconstructed signal from the two wire thermocouple requires no compensation for ω≤2ω1 where ω1 is the natural frequency of the smaller wire. A compensation factor is recommended for larger frequencies ω(approximately-greater-than)2ω1.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1144559
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    A new device for expansivity measurements of liquids at high temperature and pressure and expansivity data for liquid tin to 1450 °C (1994)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 65 (1994), S. 3258-3262 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: We have developed a new technique for measuring thermal expansion of liquids at high temperature. Our device, the volumeter, is a volumetric dilatometer which uses liquid tin to transmit volume changes to a series of electrical contacts. Measurements can be carried out from 250 °C to at least 1450 °C irrespective of the viscosity of the sample. In addition, our technique allows for the direct determination of volume changes due to melting and crystallization, as well as the volumetric properties of heterogeneous mixtures of materials. Furthermore, the device is designed to operate inside an internally heated gas-pressured vessel, allowing for the determination of compressibility. We have measured the thermal expansivity of tin from 435 to 1445 °C. Our data match previous measurements using the Archimedean technique to within 4% and shows the volumetric expansivity of tin to have a temperature dependence of −4×10−9 °C−2. Preliminary measurements of the thermal expansivity of a high-viscosity silicate liquid show a wide degree of scatter but fall within previous estimates based on density data. Improved performance of the device may require its operation under pressure.
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    URL: http://dx.doi.org/10.1063/1.1145220
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    A sensitive low-power homodyne reflectometer for impedance measurements at 0.25–1.0 GHz (1994)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 65 (1994), S. 445-448 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: We describe a single-sideband homodyne reflectometer for sensitive impedance measurements in the 1 GHz range on electronic devices at liquid-helium temperatures and below. At 50 pW measurement power, the instrument is capable of resolving a fractional change of 10−5 in the impedance of a nominally 50 Ω resistive device with a measurement time of one minute. We include details of an application to ac magnetoconductance measurements on mesoscopic devices, and an in situ calibration method for this application.
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    URL: http://dx.doi.org/10.1063/1.1145154
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    Devices for maintaining optical access in high-temperature coal combustion environments. II. Sonic and supersonic flow regions (1994)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 65 (1994), S. 466-471 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: Application of optical diagnostic techniques and instruments in the high-temperature coal combustion environments of large-scale facilities requires a clear optical path into and out of the particle-laden gas stream for long periods of time. In this paper, we describe devices for making long-term optical measurements in the sonic and supersonic regions of a coal combustion flow where, in general, the gas stream is a high-speed flow at high temperature and pressure. The design and operation of the devices are discussed and schematics are presented. Successful operation of the devices for over 900 h demonstrates their long-term reliability.
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    URL: http://dx.doi.org/10.1063/1.1145158
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    Versatile model position monitoring system (1994)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 65 (1994), S. 481-484 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: A nonintrusive optical model displacement monitoring system is presented, which was primarily developed for wind tunnel model monitoring purposes but proved to be extremely versatile, reliable, and easy to handle, mainly due to its design principles of operating with a variable number of independent optical sensing units and needing no special preparation of the object to be monitored except for a sufficiently high lighting contrast between object and background.
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    URL: http://dx.doi.org/10.1063/1.1145161
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    A simple liquid nitrogen gas-flow cryostat for variable temperature laser luminescence studies (1994)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 65 (1994), S. 503-504 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: A liquid nitrogen gas-flow cryostat is described which provides steady temperatures between 77 K and room temperature for variable temperature laser luminescence studies. The cryostat is constructed from common laboratory apparatus and requires no quartz glassware. Liquid nitrogen is consumed by the cryostat at a rate of 1 l per hour.
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    URL: http://dx.doi.org/10.1063/1.1145165
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    A simple method to monitor the intensity profile of a pulsed laser beam with micrometer resolution (1994)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 65 (1994), S. 511-512 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: A simple method is demonstrated for monitoring the time integrated intensity profile of a pulsed laser beam based on desorption from homogeneous films of Rhodamine 6G dye. The method offers micrometer resolution, and for the case of a Gaussian beam profile the fluence scale may be calibrated.
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    URL: http://dx.doi.org/10.1063/1.1145214
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    Large area thermal target board: A new design (1994)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 65 (1994), S. 519-520 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: A large area (1.8 m by 1.8 m), uniform temperature, thermal target was used for characterization of phenomena that impact target contrast. The target board is equipped with several bar patterns. It has a unique design that uses a tilted oven surface making it lightweight with near perfect transition between the hot and cold portions of the bar patterns. The oven surface maintains a ±1 °C uniformity when heated to 10–20 °C above ambient temperature.
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    URL: http://dx.doi.org/10.1063/1.1145117
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    Narrow-line, low-amplitude noise semiconductor laser oscillator in the 780 nm range (1994)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 65 (1994), S. 3628-3633 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: We present a narrow-band and low-intensity noise laser oscillator around 780 nm built from a commercially available laser diode. We have stabilized the frequency of two extended cavity diode lasers on the same high finesse Fabry–Pérot cavity using a wide-band electronic feedback loop. We have reduced the relative linewidth of the two lasers down to 570 Hz and strongly concentrated their energy: 95% in a relative bandwidth smaller than 10 kHz. The intensity noise of this device corresponds to the shot noise for Fourier frequencies larger than a few megaHertz. © 1994 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1144483
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    Automated null ellipsometer with rotating analyzer (1994)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 65 (1994), S. 3657-3660 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: An automated version of a spectroscopic ac null ellipsometer is described. By simultaneous variation of the angle of incidence and the polarizer azimuth, circular polarization of the reflected radiation can be obtained for any sample configuration. This state of polarization is checked by a rotating analyzer detector system with lock-in technique, thus achieving the highest precision that is theoretically possible. The experimental details including the minimization routine (simplex method) are presented. First experiences gained with dielectric function spectra of InP show the high reproducibility and accuracy of the arrangement. From numerically calculated second derivatives the energy and type of critical interband points are determined. © 1994 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1144487
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    Triggerable spark gap switches for pulsed gas lasers (1994)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 65 (1994), S. 3030-3031 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: Two simple three-electrode spark gaps have been constructed to operate at high voltages up to 30 kV for use in a gas laser triggering system. The performance of each spark gap has been tested in a nitrogen laser system designed for this purpose, and the results are described in this report. The pressure-controlled spark gap has shown better results in terms of stability and lifetime, and it is highly reliable for high repetition rate switching.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1144598
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    Eliminating microchannel plate response to scattered laser light in a multiphoton ionization experiment (1994)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 65 (1994), S. 3036-3037 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: A simple technique is demonstrated for preventing microchannel plate (MCP) response to scattered laser light in a multiphoton ionization experiment. The MCP is gated on after the laser pulse, with a turn-on time of less than 1 μs, by switching its cathode from 0 to −1900 V. The high-voltage pulse circuit uses power MOSFETs and was designed according to the procedure of Baker and Johnson [Electron. Lett. 29, 56 (1993)].
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1144601
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    Applications of resonance ionization mass spectrometry (1994)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 65 (1994), S. 2433-2459 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: We describe here several types of mass spectrometry in which the mass selectivity is combined with a highly selective laser ionization method to achieve both high sensitivity and very high selectivity. These methods combine the most sensitive and highly selective laser ionization methods with mass selectivity in order to improve on both the sensitivity and the Z and A selectivity previously achievable in detecting atomic species. Applications of these methods include the dating of geophysical specimens, the on line analysis of rare short-lived isotopes produced in high-energy collisions, the detection of low levels of heavy metals or radioactive isotopes in biological samples, the detection of impurities in ultrapure materials, and a host of other applications. Because some versions of this method offer sensitivity to a hundred atoms of a particular isotope of an element in a macroscopic sample, there are new possibilities for fundamental studies of rare events. Several types of facilities for elemental and isotopic analysis will be described.
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    URL: http://dx.doi.org/10.1063/1.1144702
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    Magnetic pulse compressor for prepulse discharge in spiker-sustainer excitation technique for XeCl lasers (1994)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 65 (1994), S. 2475-2481 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: A high-voltage pulse output modulator using a step-up transformer with two stages of magnetic pulse compression circuits has been developed as a spiker for the purpose of obtaining the breakdown of the gas mixture when using the spiker-sustainer excitation technique for pumping XeCl discharge lasers. When the transformer input is fed by a current pulse with a peak value and a full width of 1.16 kA and 1.6 μs, respectively, formed by a discharge of an initially charged 19-kV, 57-nF capacitance in series in the transformer primary loop, the 2.7-nF output capacitor bank (Cp) of the spiker can be charged up to 67 kV with a (10%–90%) rise time of 59 ns. The modulator has been tested at a repetition rate of up to 600 Hz in burst mode using a resistor in parallel with Cp as the load.
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    URL: http://dx.doi.org/10.1063/1.1144705
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    High-temperature scanning tunneling microscope with a novel sample heater and interchangeable scan heads (1994)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 65 (1994), S. 2519-2522 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: A UHV-compatible, high-temperature scanning tunneling microscope (STM) with a sample stage incorporating a Si wafer as a resistive heater is described. The design allows for rapid interchange of scanning tubes so that the maximum scan size can be varied. The thermal stability of the microscope is excellent, allowing real-time studies of faceting and grain growth of metal surfaces at temperatures up to 400 °C with a long term drift of ∼0.05 A(ring)/s.
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    URL: http://dx.doi.org/10.1063/1.1144644
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    Resonance response of scanning force microscopy cantilevers (1994)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 65 (1994), S. 2532-2537 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: A variational method is used to calculate the deflection and the fundamental and harmonic resonance frequencies of commercial V-shaped and rectangular atomic force microscopy cantilevers. The effective mass of V-shaped cantilevers is roughly half that calculated for the equivalent rectangular cantilevers. Damping by environmental gases, including air, nitrogen, argon, and helium, affects the frequency of maximum response and to a much greater degree the quality factor Q. Helium has the lowest viscosity, resulting in the highest Q, and thus provides the best sensitivity in noncontact force microscopy. Damping in liquids is dominated by an increase in effective mass of the cantilever due to an added mass of the liquid being dragged with that cantilever.
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    URL: http://dx.doi.org/10.1063/1.1144647
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    High-precision harmonic magnetic-field measurement and analysis using a fixed angle Hall probe (1994)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 65 (1994), S. 2548-2555 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: A special theoretical concept involving the harmonic magnetic-field measurement and analysis method using a fixed angle Hall probe was developed at the Synchrotron Radiation Research Center (SRRC) for measuring as well as analyzing the triple bending achromat magnets of the storage ring. The method can be used to simulate the harmonic magnetic-field calculation of the two-dimensional (2D) "magnet'' program. This method has a quite simple mechanism. The Hall plate was fixed at a 0° angle with respect to the horizontal plane of magnet to measure only the vertical field. Additionally, the 2D nonlinear least-square fitting was used to fit the mapping data so as to find the normal and skew multipole field strength. If necessary, the angle of Hall probe could be rotated 90° precisely for measuring the horizontal field. Consequently, the skew dipole field could be obtained. A real-time Hall-probe automatic magnetic-field measurement system was also developed for fulfilling the concept of the harmonic field measurement. Some special mapping trajectories for different kinds of magnets were discussed to match this special theoretical concept with the analysis methodology. This was done so as to obtain the reliable and accurate harmonic field strength. The accuracy and precision of the harmonic field strength measurement and analysis of this method being better than ±0.01% was confirmed by experimental results.
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    URL: http://dx.doi.org/10.1063/1.1144650
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    Improved optical tomography device (1994)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 65 (1994), S. 2574-2579 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: We report the development of an improved optical tomography diagnostic which measures the velocity-space distribution of a laboratory plasma in two dimensions. The new device is capable of imaging plasma distributions over a wider range of magnetic fields and plasma column diameters than the previous design, while minimizing the risk of misdiagnosis due to perturbations caused by inserting the device in the plasma. Computer-aided control of the diagnostic allows a greater number of single-dimensional scans to be collected in a shorter amount of time, resulting in increased resolution of the reconstructed image while freeing up more time for the user to perform the experiment. Recent data using the new device are presented to show improvement of resolution gained by doubling the number of total scans. Finally, we present a method to identify velocity-space nonuniformities without the need to reconstruct a complete image.
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    URL: http://dx.doi.org/10.1063/1.1144653
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    Ion temperature measuring probe in a strongly magnetized plasma (1994)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 65 (1994), S. 2607-2614 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: A probe for the measurement of the ion temperature in a strongly magnetized plasma is described. The positive-ion current to a cylindrical probe, whose axis is set parallel to the magnetic field, is calculated in the collision-free regime as a function of the ion temperature and the magnetic-field strength. It is assumed that the electron Larmor radius is negligibly small compared to the radius of the cylinder. Only the ion Larmor radius is treated as finite. The ion temperature can be evaluated from the ratio of ion currents of the two cylindrical electrodes with different lengths, whose surfaces are parallel to the magnetic field. The effect of ion drift along the cylinder axis is also considered. Experiments have been made in the edge plasma of a JFT-2M tokamak to test the above probe for determining plasma parameters during ohmic and NBI heatings.
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    URL: http://dx.doi.org/10.1063/1.1144659
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    Performance of an inertially coupled, three-mode gravitational wave antenna prototype (1994)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 65 (1994), S. 2627-2634 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: A prototype three-mode gravitational wave antenna which employs a two-mode torsional transducer has been constructed and tested. For the torsional transducer the coupling from one stage to the next is via inertial forces, whereas in a conventional transducer the stage-to-stage coupling is proportional to the relative displacements via the springs. Experiments with our antenna-torsional transducer prototype demonstrate a maximum antenna bandwidth of 260 Hz (29% of the antenna resonant frequency of 900 Hz) and a mechanical amplification factor of 40. A mathematical model for the three-mode antenna has been developed and predictions of the system transfer functions and transient response are in close agreement with the measurements. Through the optimization of the transducer parameters we find that maximum fractional antenna bandwidths near 30% may be simultaneously achieved with mechanical amplification factors of 100 or more. Furthermore, the torsional transducer has a larger mechanical gain-antenna bandwidth product than a linear transducer with similar masses.
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    URL: http://dx.doi.org/10.1063/1.1145208
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    Complex dielectric constant measurement of samples of various cross sections using a microwave impedance bridge (1994)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 65 (1994), S. 2653-2657 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: A microwave impedance bridge covering from 8.2 to 12.4 GHz used for measuring complex dielectric constants over a wide temperature range is described. This apparatus is suited for materials formed into solid posts having different cross sections. The effective diameters for use in the analysis of circular, elliptical, or rectangular cross-section posts are presented. The effective diameters are applied to determine the complex dielectric constant of rectangular-shaped conducting polymer film. The frequency and temperature dependence of the dielectric constant and conductivity are presented, and compared with those obtained using a microwave cavity perturbation technique at 6.5 GHz. The bridge results are well suited for independent determination of the depolarization factor of a rectangular post for use in analysis of results of the cavity perturbation method.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1144665
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    Fabrication of optical fiber probes for nanometer-scale dimensional metrology (1994)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 65 (1994), S. 2538-2541 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: The fabrication of cylindrical probes having diameters as small as 50 nm is described in this article. The planar endface (advantageously oriented perpendicular to the axis of the cylindrical probe) and sharp 90° corners of the end portion of the probe enable accurate measurement of a feature being scanned, even at sudden jumps in the surface. Conical and flaired probes can also be fabricated with variations of this technique. The fabrication techniques described in this article are simple and inexpensive; only a Teflon beaker, optical fiber, etching solution, polymer solution, fiber cleaver, and optical microscope are necessary.
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    URL: http://dx.doi.org/10.1063/1.1144648
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    Electronic Resource
    Electronic Resource
    Practical nitric oxide measurement employing a nitric oxide-selective electrode (1994)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 65 (1994), S. 2714-2718 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: An NO-selective electrode was developed as an easily applicable tool for a real-time nitric oxide (NO) measurement. The working electrode (0.2 mm diam) was made from Pt/Ir alloy coated with a three-layered membrane. The counterelectrode was made from a carbon fiber. When a stable NO donor, S-nitroso-N-acetyl-dl-penicillamine, was applied, the electrode current increased in a dose-dependent fashion. The current and calculated NO concentration showed a linear relationship in the range from 0.2 nM (S/N=1) to 1 μM of NO. The response of the electrode was 1.14±0.09 s. The effects of temperature, pH, and chemicals other than NO on the electrode current were also evaluated. Electrodes which were placed in the luminal side of rat aortic rings exhibited 30 pA of current due to NO generation induced by the addition of 10−6 M of acetylcholine. The current was eliminated in the presence of 50 μM NG-monomethyl-L-arginine, an inhibitor of NO synthase. Thus, this NO-selective electrode is applicable to real-time NO assay in biological systems.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1144674
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