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  • Articles  (9,878)
  • 2020-2020
  • 1985-1989  (9,878)
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  • 1988  (5,263)
  • 1987  (4,615)
  • Electrical Engineering, Measurement and Control Technology  (9,878)
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  • Articles  (9,878)
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  • 2020-2020
  • 1985-1989  (9,878)
  • 1980-1984
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  • 1
    Electronic Resource
    Electronic Resource
    Variable-temperature scanning tunneling microscope (1988)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 59 (1988), S. 1897-1902 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: A thermally compensated tube scanner scanning tunneling microscope (STM) has been constructed and successfully tested. This design utilizes two concentric piezoelectric tubes, one for scanning and one for thermal compensation and inertial sample translation (over several mm), as well as fine adjustment of sample position while in tunneling range. This design eliminates the need for mechanical components such as springs, levers, gears, or stepper motors that are known to result in considerable vibration sensitivity, thermal drift, and low-resonance frequencies. This new design demonstrates continuously variable-temperature operation as well as atomic resolution without vibration isolation for the first time in a STM. Thermal drift of less than 1 A(ring)/h and less than 10 A(ring)/K have been determined. Also, the lowest mechanical resonance frequency of 21 kHz makes this new design suitable for high-speed applications such as video rate scanning.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1140047
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  • 2
    Electronic Resource
    Electronic Resource
    Constant-resolution tunneling spectroscopy (1988)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 59 (1988), S. 1903-1905 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: An inelastic electron tunneling spectrometer is described which is capable of providing constant-resolution spectra over the 0 to greater than 16 000-cm−1 range. Constant-resolution data acquisition is especially beneficial in the case of electronic transitions studied by tunneling spectroscopy. Data acquired as d2V/dI2, (d2V/dI2)/(dV/dI)2, and in constant-resolution mode are compared. At intermediate and at high bias, either of the two latter data-acquisition methods is superior to the first. At high bias voltage, constant-resolution spectra are superior.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1140048
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  • 3
    Electronic Resource
    Electronic Resource
    Piezodriven scanner for cryogenic applications (1988)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 59 (1988), S. 1906-1910 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: A scanning microscope stage has been developed for use at cryogenic temperatures. The stage uses a piezoelectric driving element and circular flexure hinges to achieve a slow scan travel of greater than 10 μm and a near-resonance travel of 100 μm while immersed in liquid helium at 4.2 K. The scanner has been operated inside a pressure cell in a dilution refrigerator, where it dissipates less than 150 μW of heat at 100 mK.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1140049
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  • 4
    Electronic Resource
    Electronic Resource
    Rapid electromechanical phase shifting in differential holography (1988)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 59 (1988), S. 1920-1923 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: Procedures for the rapid and precise control by electromechanical means of the reference beam phase shift during differential holography are described. Phase shift is created with the use of a piezoelectric ceramic translator that is driven by a two-step voltage pulse to minimize mechanical ringing. The resultant suppression of resonant vibration permits an order of magnitude reduction in the time interval between the exposures. The adjustment of the phase shift signal is assisted by use of feedback control arrangement to stabilize an interferometer.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1140051
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  • 5
    Electronic Resource
    Electronic Resource
    Conversion and amplification of photomultiplier anode current in multiple-frequency phase fluorometry (1988)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 59 (1988), S. 1924-1927 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: We have designed and built a low-cost current–voltage converter with a bandwidth larger than 200 MHz and a fixed ac insertion gain of 20 dB for use in multiple-frequency phase fluorometry (MFPF). We describe its application with the Hamamatsu R928 photomultiplier (PMT) and discuss problems of radio-frequency (rf) interference, signal-to-noise ratio (S/N), PMT nonlinearity, and overall frequency bandwidth. The separation of ac and dc signal paths introduces the possibility of direct determination of relative modulation in two simultaneous measurements. We demonstrate that systematic errors such as PMT nonlinearity can be completely eliminated in MFPF by an appropriate experimental procedure and report an accuracy of our dual-beam instrument of 5 ps.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1140052
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  • 6
    Electronic Resource
    Electronic Resource
    Resolution of time-of-flight mass spectrometers evaluated for secondary neutral mass spectrometry (1988)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 59 (1988), S. 1947-1950 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: Mass resolution of a time-of-flight mass spectrometer with a two-stage electrostatic reflector is calculated for secondary neutral mass spectrometry. The instrument parameters are optimized for energy and space focusing: correcting the flight time difference due to the energy width ΔE of sputtered particles and the spatial width Δs of an ionizing laser beam. The effect of Δs can be compensated by applying an acceleration field to the ionizing region, and the maximum resolution becomes about 1000 for ΔE=10 eV and Δs=1.0 mm.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1140056
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  • 7
    Electronic Resource
    Electronic Resource
    High-resolution position-sensitive detector (1988)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 59 (1988), S. 1954-1956 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: This paper describes a position-sensitive detector for particles or photons which has a spatial resolution of about 15 μm. The active area is about 1.3 mm in diameter. This represents an improvement of conventional position-sensitive detection capability by about one order of magnitude and should be useful in spectrometry, spectroscopy, and atomic collision experiments.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1140058
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  • 8
    Electronic Resource
    Electronic Resource
    Absolute calibration of an atomic helium beam time-of-flight apparatus by flight path variation (1988)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 59 (1988), S. 1957-1964 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: Virtually all inelastic helium atom scattering experiments utilize time-of-flight (TOF) analysis to energy analyze the scattered beam. To date, the demands upon the accuracy of these TOF measurements have not been particularly great (typically a few percent), and rather rudimentary calibration techniques have sufficed. For certain experiments, e.g., for time-resolved measurements of specular scattering to determine surface-bound states of helium or to observe surface-step interference, this is no longer the case. We describe an in situ calibration technique based upon a variation of the TOF flight path that allows us to calibrate our path length and time origin to within a few millimeters and microseconds, respectively (〈2×10−3). A comparison with "zero flight time'' laser timing measurements shows that finite drawout/transit times through the beam detector can introduce nonnegligible systematic errors into the laser calibration technique, even in the present favorable instance (light beam mass, drawout along the beam axis). We demonstrate the utility of surface diffraction as either a consistency check or to accurately determine unknown reciprocal lattice vectors.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1140059
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  • 9
    Electronic Resource
    Electronic Resource
    New lens for a low-voltage scanning electron microscope (1988)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 59 (1988), S. 1985-1989 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: This article introduces the idea of a "half '' pole-piece to modify single pole-piece lenses, enabling them to form an electron probe a few millimeters in front of the pole face. This modified single pole-piece lens has relatively low spherical and chromatic aberration coefficients. If 2 mm is an acceptable working distance, then a 6-A(ring) radius probe can be made using 5-kV electrons.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1140063
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  • 10
    Electronic Resource
    Electronic Resource
    Conceptual design and numerical simulation of a correlation diagnostic for measurement of magnetic fluctuations in plasmas (1988)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 59 (1988), S. 1990-1997 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: It has been previously suggested that crossed-sightline correlation of electron cylotron emission might be used to measure magnetic fluctuations in high-temperature plasmas. Reported here are the results of a continuing project to determine under what conditions (if any) this measurement will be feasible. An initial conceptual design for the device hardware has been completed. Large portions of the numerical simulation are working, including ray-tracing and emission/absorption packages. An initial discussion of data analysis for the experimental data is presented, and an analysis of the uncertainty in the line center (magnetic field) measurement in terms of the experimental uncertainties is given.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1140064
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  • 11
    Electronic Resource
    Electronic Resource
    New UHV dilatometer for precise measurement of internal stresses in thin binary-alloy films from 20 to 750 K (1988)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 59 (1988), S. 2012-2017 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: We describe a new dilatometric device for internal stress measurements of thin binary-alloy films, able to operate in ultrahigh vacuum in the temperature range 20–750 K. Using a three-terminal capacitor method, the displacement of the free end of a thin cantilever substrate is monitored by the capacitance change. With a sensitivity of 1 nm for substrate displacements, the resolution for stress detection is 105 Pa in a 100-nm-thick film. Simultaneously with the stress measurement, the electrical resistivity of the film can be determined on the same substrate. The direct comparison of electrical and mechanical thin-film properties gives the ability to obtain additional information on the growth process and on the thin-film structure. Measurements of a crystalline Cu film and an amorphous Zr20 Co80 alloy film are shown.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1140017
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  • 12
    Electronic Resource
    Electronic Resource
    Variable-depth calorimetry of a layered material (1988)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 59 (1988), S. 2031-2035 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: We have investigated the use of frequency variation in ac calorimetry in the measurement of thermal quantities within controllable distances of the sample heater and thermometer. This technique, useful in studies of heterogeneous samples where only a small part of the sample is of interest, e.g., surfaces, thin films, and interfaces, is applied to study the thermal properties of a test sample made from indium (In) sandwiched between layers of bulk gallium arsenide. We measure and analyze the frequency dependence of the thermal response of the sample, as well as the variation with frequency of the relative size of the anomaly observed at the In superconducting transition. The data are consistent with a model assuming a thermal diffusion-limited sampling volume.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1140020
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  • 13
    Electronic Resource
    Electronic Resource
    Dynamic response of the conical-tip thin-film thermometer (1988)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 59 (1988), S. 2036-2040 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: The dynamic response of the conical-tip thin-film thermometer has been investigated through both experiments and numerical simulation. The numerical model extends the theoretical basis for the response from the simplified stagnation-region analysis to the cone geometry within the laminar flow regime, while taking into account the coupled thermal response of the fluid and the solid body. The experimental measurements, particularly the velocity scaling behavior, present useful information in their own right in addition to providing a check on the behavior of the model. This work confirms the shape of the dynamic response function and a velocity-independent spatial frequency response, a characteristic of the stagnation-region theory and an observed feature of hemispherical-tip probes. Previous authors have reported an empirically derived velocity dependence for the conical-tip sensor. In light of the work reported here, the validity of such empirical relationships must be seriously questioned.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1140021
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  • 14
    Electronic Resource
    Electronic Resource
    Measurement of interfacial dilational properties: A software-driven apparatus (1988)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 59 (1988), S. 2045-2050 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: The construction of a time-resolved surface viscoelastometer for the study of fluid/fluid interfaces is described in detail. Instrument design and operation are based on the formalism of systems theory. An interfacial-area change (i.e., an external stimulus) is generated according to a given time function; the ensuing dynamic surface tension response is continuously recorded in synchronism with the stimulus. The principal characteristic of the equipment is a computer-controlled mechanical motion of the area-confining device (i.e., of a particular ring barrier, in place of the traditional linear barriers). The software allows a wide variety of oscillatory or transient experiments to be conducted. Instrument performance is illustrated by a typical experimental response, obtained under conditions of small-amplitude area perturbation, for a submicellar aqueous solution of surfactant. The recorded trace is fitted to a theoretical two-parameter model. Results show the effectiveness of the controlled-surface-deformation technique, allowed by the instrument, for determining static and dynamic interfacial properties.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1140023
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  • 15
    Electronic Resource
    Electronic Resource
    Acoustic gas density measuring cell (1988)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 59 (1988), S. 2059-2062 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: Preliminary experiments reported in 1983 suggested that the density of a known gas could be determined, in principle, by measuring the alternating pressure of an acoustic field set up in the gas. A density measuring cell has now been developed that is inherently fast acting (overall response time less than 3 s) and linear to within ±0.3% (of reading). It has been used over an approximately 700:1 density range, from 30 g/m3 to 20 kg/m3. Density determinations near room temperature and pressures from 0.1 to 20 atm were shown to be accurate within ±2% (of reading) up to about 0.1 kg/m3 and within ±0.2% for higher densities.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1140025
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  • 16
    Electronic Resource
    Electronic Resource
    Paralleled transconductance ultralow-noise preamplifier (1988)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 59 (1988), S. 2070-2074 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: A simple NJFET preamplifier was constructed from commercial parts using parallel input devices in a cascode configuration. The equivalent input noise resistance was 8.5 Ω (0.38 nV/(Hz)1/2) at 1 kHz, and 12 Ω (0.45 nV/(Hz)1/2) at 100 Hz, measured at room temperature, independent of the source resistance. For 50-Ω sources, a gain of 29 dB was achieved from 3 Hz to 13 MHz. The input noise equivalent resistance is verified by measuring the thermal noise of low-valued wire-wound resistors. Circuit utility is demonstrated by noise measurements performed on GaAs Ohmic contacts at room temperature, under various bias conditions. Design considerations for using parallel input devices, the bias criteria for them, and possible design extensions are discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1140027
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  • 17
    Electronic Resource
    Electronic Resource
    Laser optical pumping of rare-gas metastable atom beams (1988)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 59 (1988), S. 2083-2084 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: Time-of-flight techniques are used to demonstrate the very high rare-gas metastable atom polarizations that can be achieved in a beam through optical pumping with a simple frequency-modulated multimode dye laser.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1140266
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  • 18
    Electronic Resource
    Electronic Resource
    Approximation of the nonparalyzable dead time by the shortest time interval (1988)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 59 (1988), S. 2086-2087 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: The method based on the approximation of nonparalyzable dead time by the shortest time interval between two successive pulses at the output of the radiation detection system or any other system for processing and counting random event trains has been proposed and investigated.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1140031
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  • 19
    Electronic Resource
    Electronic Resource
    Pulsed chemical HF laser using graphite continuous electrodes for transverse discharge stabilization (1988)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 59 (1988), S. 2090-2091 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: We report results obtained in the operation of a chemical HF laser using a mixture of SF6 and technical grade C3H8 reacting in a transverse high-voltage discharge in which a pair of inexpensive continuous electrodes of polycrystalline graphite are used as the only means for stabilizing the discharge and avoiding the formation of arcs during excitation of the laser medium. Energies of up to 60 mJ per pulse in stable operation are obtained from a 0.1-l volume.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1140033
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  • 20
    Electronic Resource
    Electronic Resource
    Semiconducting wafer form shaping with an electric discharge machine (1988)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 59 (1988), S. 2094-2096 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: Gallium can be used as a temporary glue for semiconducting wafer mounting. The good electric contact between the electrode, the gallium layer, and the semiconducting wafer makes the spark cutting and the semiconducting wafer form shaping much easier. After wafer spark cutting, the residual gallium can be easily removed by a cotton swab from the surface of the wafer in warm isopropyl alcohol (IPA). Also, in this report, improved circuitry of the electric discharge machine for easy and economical construction is described. Gallium arsenide wafers have been form shaped by the present method.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1140035
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  • 21
    Electronic Resource
    Electronic Resource
    Time-of-arrival digital photon correlator (1988)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 59 (1988), S. 2096-2098 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: Design and fabrication of the R 6501 microprocessor-based photon correlator, equally applicable to Gaussian as well as non-Gaussian radiation, is described. It works on the principle of directly registering the arrival times of photoelectrons.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1140036
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  • 22
    Electronic Resource
    Electronic Resource
    1-mm wave ESR spectrometer (1988)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 59 (1988), S. 1345-1351 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: An ESR spectrometer operating at 250-GHz frequency (1.22-mm wavelength) and 9-T magnetic field is described. The utilization of far-infrared (FIR) technology greatly simplifies its design and performance. Good frequency and field stability are achieved by unique designs which also conveniently permit the magnetic field to be swept. The potential utility of FIR–ESR is illustrated with examples of spectra from polycrystalline and liquid samples. In the latter case the increased spectral sensitivity to motional dynamics is stressed. Several ways in which the FIR–ESR spectrometer may be improved are also discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1139720
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  • 23
    Electronic Resource
    Electronic Resource
    Measurement of the spatial neutral deuterium temperature distribution in the HBTX1B reversed-field pinch by fluorescence scattering (1988)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 59 (1988), S. 1461-1463 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: The spatial neutral deuterium temperature distribution has been made in the HBTX1B reversed-field pinch plasma device by Balmer-beta fluorescence scattering. This measurement is based on tuning a dye laser to the n=2–4 transition of deuterium and passing it through the deuterium plasma with sufficient power to saturate the selected transition. The technique, hitherto used to determine neutral densities and energies, has been extended by means of an optimized two-channel narrow-band interference-filter arrangement to analyze the scattered spectrum. Spatial resolution is achieved by a scanning Risley prism arrangement. Neutral temperatures in the range 20–150 eV have been measured and the spatial distribution is consistent with neutral particle analyzer results and an ion power balance model proposed for the reversed-field pinch.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1139688
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  • 24
    Electronic Resource
    Electronic Resource
    The LIDAR Thomson scattering diagnostic on JET (invited) (1988)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 59 (1988), S. 1451-1456 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: By combining the time-of-flight or LIDAR principle with a Thomson backscatter diagnostic, spatial profiles of the electron temperature and density are measured in a magnetically confined fusion plasma. This technique was realized for the first time on the JET tokamak. A ruby laser (3-J pulse energy, 300-ps pulse duration, 0.5-Hz repetition rate) together with a 700-MHz bandwidth detection and registration system yields a spatial resolution of about 12 cm. A spectrometer with six channels in the wavelength range 400–800 nm gives a dynamic range of the temperature measurements of 0.3–20 keV. The stray light problem in the backscatter geometry is overcome by spectral discrimination and gating of the photomultipliers. A ruby filter in the spectral channel containing the laser wavelength allows calibration of the vignetting along the line of sight by means of Raman scattering, enabling the measurement of density profiles. The low level of background signal due to the short integration time for a single spatial point yields low statistical errors (ΔTe /Te ≈6%, Δne /ne ≈4% at Te =6 keV, ne =3×1019 m−3 ). Goodness-of-fit tests indicate that the systematic errors are within the same limits. The system is described and examples of measurements are given.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1139686
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  • 25
    Electronic Resource
    Electronic Resource
    Double-pulse Nd:glass laser system for Thomson scattering diagnosis of high-temperature plasmas (1988)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 59 (1988), S. 1473-1475 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: Beam properties of a twice Q-switched Nd:glass laser operated at 1053 and 527 nm have been examined with respect to energy, pulse width, divergence, and conversion efficiency at a pulse separation of 75 μs. Q switching occurred twice within a flashlamp burst (FWHM: 160–175 μs). Maximum IR energies of 24 joules per pulse (Jpp) were measured with pulse widths of 25 and 40 ns and divergence values of 0.6 and 0.7 mrad for the first and second pulses, respectively. Maximum second-harmonic energies of 14 J (single pulse) and 4 Jpp were measured with peak power-density conversion efficiencies of 45% and 30%. Use of this laser at 1053 nm, in conjunction with generation III GaAs detectors, offers improvement over current source/detection systems (ruby/S-20) for diagnosis of high-temperature plasmas (Te 〉10 keV).
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    URL: http://dx.doi.org/10.1063/1.1140256
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  • 26
    Electronic Resource
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    Field-dependent dipole matrix elements and their application to the calculation of plasma-broadened line profiles (1988)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 59 (1988), S. 1512-1514 
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    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: We have computed field-dependent wavefunctions and dipole matrix elements for hydrogenic ions in the presence of a uniform electric field; we present the results for transitions connecting the ground and excited states. As an application we use these elements to compute Stark-broadened static line profiles and compare with similar ones that use field-independent matrix elements. The line-shape sensitivity to the use of field-dependent matrix elements is discussed.
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    URL: http://dx.doi.org/10.1063/1.1140180
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    Utilization of charge exchange recombination spectroscopy for the study of metallic ion transport in TFTR (1988)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 59 (1988), S. 1518-1520 
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    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: Charge exchange recombination spectroscopy has been used to observe transitions originating from hydrogen-, helium-, and lithiumlike charge states of medium-Z metallic impurities in TFTR. The temporal and spatial densities of these ions were measured in ohmic and neutral beam heated plasmas. These preliminary results agree with predictions of a transport code.
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    URL: http://dx.doi.org/10.1063/1.1140182
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    Radiative and diffusional effects to the population densities of the excited-state atoms in hydrogen plasma (1988)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 59 (1988), S. 1524-1526 
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    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: Collisional–radiative (C–R) calculations based on the generalized multithermal equilibrium (GMTE) model are used to find the effects of radiative transfer and diffusion on excited-state populations in a hydrogen plasma. Radiation absorption factors are introduced to study the nonlocal aspects of radiative transfer. Unlike escape factors, the absorption factor can represent the absorption of more radiation than that emitted, and hence provides C–R analysis in strong gradients such as the outer edge of arcs or plasma jets. The Boltzmann temperatures of excited atoms are found not necessarily equal to the electron kinetic temperature, contrary to the usual assumption.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1140184
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    Visible and VUV spectroscopic diagnostics on Heliotron E (1988)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 59 (1988), S. 1533-1535 
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    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: Diagnostic applications of visible and VUV spectroscopic techniques, as applied to the currentless Heliotron E plasma device, are described. Visible spectroscopy has been used to measure (i) ion temperature, (ii) proton-to-electron density ratio, (iii) Zeff by charge exchange recombination from an intense neutral beam, (iv) radial electric field by poloidal rotation velocity measurement, and (v) electron density around an ablating pellet by a Stark profile. VUV spectroscopy has been used to investigate emission spectra due to multiply ionized impurity species. This information is used to measure the densities of these species, and to learn about the transport of these particles. Recently, a flat-field survey spectrometer has been constructed and used to study the emission spectra due to metallic impurities in ICRF-heated plasmas.
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    URL: http://dx.doi.org/10.1063/1.1140187
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    Optical time-domain reflectometer for ICF burn dynamics (abstract) (1988)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 59 (1988), S. 1537-1537 
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    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: A new ultrafast all-optical sensor for studies of ICF burn dynamics is described. The sensor measures the change in reflectivity at the interface between two glass plates. The front plate uses uranium-oxide doped silica while the rear plate uses pure silica with an index matching coating. Neutron-induced fissions preferentially change the refractive index of the front plate and the resulting mismatch is measured with a probe laser. A threshold neutron yield requirement of 2×109 is estimated for a sensor with 30 wt. % U-238 doping located 2 mm from the target. A time resolution 〈20 ps is predicted. Further properties and construction details will be presented.
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    URL: http://dx.doi.org/10.1063/1.1140190
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    Multibeam receiver for millimeter-wave radio astronomy (1988)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 59 (1988), S. 1911-1919 
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    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: An eight-beam receiver system for millimeter-wave radio astronomy is described. The receiver is designed to map spatially extended radio sources in both spectral line and continuum emission at a wavelength of 1.2 mm. This receiver is now in use on the 12-m radio telescope on Kitt Peak in Arizona.
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    URL: http://dx.doi.org/10.1063/1.1140050
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    Emissive probe measurement of electron temperature in high-pressure plasmas (≥1 mTorr) (1988)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 59 (1988), S. 2002-2007 
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    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: A new method was investigated to determine the electron temperature with the emissive probe. The basis of the method is the use of a functional relationship between the floating potential and the heating voltage of the emissive probe. A new expression for the change of the floating potential was obtained as functions of the heating voltage and the electron temperature. This expression enabled us to determine the electron temperature from the measured floating potential. An experimental verification of the present method was made at relatively high pressures (above 1 mTorr). It was shown that the electron temperatures measured by the present method were consistent with those obtained by Langmuir characteristics and that the error in them did not exceed 10%. It was emphasized, further, that the method is very attractive because the circuit required is the same as that used in potential measurement.
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    URL: http://dx.doi.org/10.1063/1.1140066
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    Optical interferometry for measuring instantaneous thickness of transparent solid and liquid films (1988)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 59 (1988), S. 2018-2022 
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    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: An optical-interference method is proposed which enables measurements of instantaneous, uniform thickness of the order of 10 μm–1 mm of transparent (or weakly absorbing) solid materials or liquids. It uses a converging lens set by its focal length separated from the subject film. The lens turns parallel, monochromatic, coherent rays in an expanded laser beam into converging rays propagating as spherical waves toward the subject film. The rays reflected at the front and rear surfaces of the film pass again through the lens to be retransformed from the spherical waves into the plane waves, and form interference fringes on a screen. Knowing the number of fringes provided by the rays which are incident on the subject film at angles between two specified angles, we can readily calculate the thickness of the film. A prototype apparatus based on this method has been constructed and used successfully in measuring the thicknesses of both solid and liquid films.
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    URL: http://dx.doi.org/10.1063/1.1140018
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    Direct pulse technique for spontaneous polarization dynamics and molecular reorientation processes in ferroelectric liquid crystals (1988)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 59 (1988), S. 2023-2030 
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    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: A method has been devised for studying the spontaneous polarization, dynamics of polarization reversal, and the molecular reorientation processes that occur in the bulk and surfaces of ferroelectric liquid crystals. These studies have been carried out by analyzing the current response to triangular- and square-wave forms. The current response to a triangular wave yields the spontaneous polarization by conveniently subtracting the background contribution due to the conductive and capacitive currents. Molecular reorientation processes which take place within the bulk and the boundary surface layer can be studied by the appearance of polarization current peaks on the triangular-wave response. The dynamics of polarization reversal between bistable states and of the polarization change between the zero-field relaxed state and either of the saturation remanent polarization states have been studied by applying "symmetric'' and "asymmetric'' square waves. The technique can also be successfully applied to solid ferroelectrics for studying the spontaneous polarization and the domain dynamics during switching.
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    URL: http://dx.doi.org/10.1063/1.1140019
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    High-precision temperature controller based on phase-locked loop circuits (1988)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 59 (1988), S. 2041-2044 
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    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: We report a low-cost, high-performance analog electronic temperature controller based on an alternative technique to resistive bridges. The proposed device shows linearity around the working temperature, high resolution, and good transient behavior.
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    URL: http://dx.doi.org/10.1063/1.1140022
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    Measurements of rheological fluid properties with the falling needle viscometer (1988)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 59 (1988), S. 2051-2058 
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    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: The use of data from the falling needle viscometer to determine the rheological properties of purely viscous non-Newtonian fluids is described. From the solution of the basic flow equation, which is given in tabular and graphical form, a method is presented to determine rheological flow curves for both power law and more generalized rheological fluids. The use of the instrument to determine the zero shear rate viscosity is also described and a method of fitting appropriate constitutive equations to the data is discussed and illustrated by examples. Finally, a technique for measuring fluid densities using the falling needle viscometer is presented that is applicable to both Newtonian and power law fluids.
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    URL: http://dx.doi.org/10.1063/1.1140024
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    Characterization of the piston gauge to assess the suitability of its use with several working fluids up to 5 MPa (1988)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 59 (1988), S. 2063-2069 
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    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: This paper describes the systematic studies carried out to characterize the controlled clearance piston gauge in the pneumatic pressure region up to 5.09 MPa by measuring its fall rate as a function of the jacket pressure (Pj) using different working fluids such as argon, nitrogen, helium, and hydrogen. It is also observed that a small ambient temperature fluctuation does not affect the overall uncertainty in the measured pressure. A relatively better reproducibility in the stall jacket pressure (Pz) values is obtained for helium and hydrogen as compared to that of argon and nitrogen; therefore it is shown that helium can also be used in addition to the commonly used nitrogen in the pneumatic pressure region. But the use of helium requires a higher value of Pj compared to that of nitrogen in order to get a good floating condition of the gauge. In addition, a detailed study is reported of the effective area of the simple piston gauge with different working fluids used during the calibration.
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    URL: http://dx.doi.org/10.1063/1.1140026
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    Integrated automatic modular measuring system (1988)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 59 (1988), S. 2075-2078 
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    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: This paper describes a versatile automatic measuring system composed of discrete modules. The modules can operate in both stand-alone and remote modes and are interconnected using an IEEE-488 bus, allowing utilization of standard measurement apparatus and peripherals. The system design allows user optimization of the measurement procedure, which can thus be tailored to meet specific experimental requirements. The flexibility of this system is demonstrated by its application in spectroscopic ellipsometry.
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    URL: http://dx.doi.org/10.1063/1.1140028
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    Digitally timed boxcar averager for analog integration of portions of a video signal (1988)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 59 (1988), S. 2079-2082 
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    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: A new system for measuring video signal intensity over selected portions of a complete video scan has been developed and applied to acquisition of LEED IV data. Unlike other systems available, this system is not microprocessor driven, but relies on appropriately timed boxcar averaging such that interfacing to the computer is relatively simple, yet data acquisition is fast. Signal to noise is theoretically better for this system since the input to the analog to digital (A/D) converter can have a lower time constant.
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    URL: http://dx.doi.org/10.1063/1.1140029
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    Probe for electrostatic wave measurements in plasmas (1988)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 59 (1988), S. 2084-2086 
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    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: We present a probe arrangement for electrostatic wave measurements in plasmas. The probe picks up potential perturbation by capacitive coupling to a copper sensor. It has the advantages of high resolution (within 5 mm) and easy construction.
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    URL: http://dx.doi.org/10.1063/1.1140030
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    Fast-scanning autocorrelator with 1-ns scanning range for characterization of mode-locked ion lasers (1988)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 59 (1988), S. 2088-2090 
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    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: We describe a rapid-scanning autocorrelator interferometer, which will be extremely useful to measure and monitor laser pulses in the 100-ps regime. A scan range as wide as 1.4 ns is achieved by using a self-compensated, rotating prism system for the generation of the optical delay. Combining this interferometer with a β-BaB2O4 crystal for second-harmonic generation, a low-cost device for real-time display of the autocorrelation function of mode-locked ion lasers is obtained.
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    URL: http://dx.doi.org/10.1063/1.1140032
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    Compact, transportable, and multipurpose high-pressure unit for UV–VIS spectroscopic measurements at pressures up to 200 MPa (1988)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 59 (1988), S. 2092-2093 
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    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: The construction of a compact, transportable, and multipurpose high-pressure unit consisting of a pressure generating system and a four-window optical UV–VIS high-pressure cell for spectroscopic measurements at pressures up to 200 MPa is described. The pressure generating system can be operated with a wide range of liquids suitable as pressurizing medium. The optical cell can be used for spectroscopic and kinetic (flash photolysis and laser induced T-jump) measurements.
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    URL: http://dx.doi.org/10.1063/1.1140034
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    Use of a frequency convertor in microwave hypersonic attenuation measurements (1988)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 59 (1988), S. 2099-2100 
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    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: We describe how a frequency convertor in a microwave system reduces the interference problem in hypersonic attenuation measurements on samples which display a temperature-dependent sound velocity.
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    URL: http://dx.doi.org/10.1063/1.1140037
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    Simple x-ray alignment monitor (1988)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 59 (1988), S. 2101-2102 
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    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: A simple x-ray alignment monitor having greater sensitivity than a hand-held fluorescent screen has been built and tested. The monitor is useful for alignment of diffractometers and powder cameras. The device is small, lightweight, rugged, and does not require a high-voltage power supply.
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    URL: http://dx.doi.org/10.1063/1.1140267
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    Combination of a scanning tunneling microscope with a scanning electron microscope (1988)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 59 (1988), S. 1286-1289 
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    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: We have placed a scanning tunneling microscope (STM) in the sample stage of a scanning electron microscope (SEM). This allows us to focus the tip on a preselected spot for STM operation with a precision of 0.5 μm. We are able to check the state of the sample and the tip during STM operation by simultaneous use of the SEM. We are also able to correlate the images given by both techniques.
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    URL: http://dx.doi.org/10.1063/1.1139710
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    Apparatus for in-situ measurements of changes in the electrical resistivity accompanying phase changes in metastable metallic alloys (1988)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 59 (1988), S. 347-350 
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    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: A new apparatus for making in-situ measurements of changes in the electrical resistivity accompanying phase transformations and structural relaxation of rapidly quenched metallic alloys is presented. Measurements may be made in vacuum or inert gas. In inert gas, the sample temperature is raised to the annealing temperature within 3–4 min with no appreciable overshoot; the long-term thermal stability is better than ±0.2 K. The measurement circuit is stable to better than 5 ppm over 24 h. The apparatus is simple, convenient to use, and flexible for changes in the experimental design.
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    URL: http://dx.doi.org/10.1063/1.1140202
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    Automatic ultrasonic measuring system using phase-sensitive detection (1988)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 59 (1988), S. 356-361 
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    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: A new ultrasonic measuring system is developed that enables us to measure the changes in the sound velocity and attenuation in MHz frequency range simultaneously and automatically. The system utilizes a gated amplifier and a phase-sensitive detector (PSD) and is controlled by a personal computer. The unique feature of the system lies in the PSD with two double-balanced mixers that enables us to obtain simultaneously the sine and cosine components of the ultrasonic signal. The phase and amplitude of the signal are calculated from them by the personal computer and are then converted to changes in the velocity and attenuation, respectively. The performance of the PSD is tested. The system is suitable for measurements at low temperatures. The temperature dependences of the velocity and attenuation in ionic crystals are measured with this system.
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    URL: http://dx.doi.org/10.1063/1.1140204
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    Frequency-modulation spectrometer for Mössbauer studies (1988)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 59 (1988), S. 362-367 
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    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: A nuclear frequency-modulation spectrometer (NFMS) for high-resolution gamma-ray spectroscopy is described in this article. As the name implies, this device operates by modulating the cross section for gamma-ray absorption. The automation of this spectrometer required the development of an interface to an Apple computer which provides a real-time data display. This interface also enables the Apple computer to control up to two Mössbauer spectrometers at once, with a real-time data display for each. A nuclear frequency-modulation spectrometer makes it possible to observe directly the phenomenon known as "rf sidebands'' in Mössbauer spectroscopy, without interference from the "parent transitions.'' The high resolution of NFMS makes it possible to examine the "rf sidebands'' for any fine structure.
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    URL: http://dx.doi.org/10.1063/1.1140205
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    Simple piezoelectric translation device (1988)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 59 (1988), S. 368-369 
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    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: We describe a piezoelectric device which allows continuous movement and high-resolution micropositioning, without distance limitation. Both mechanical construction and the electronics for the device are very simple. The movement is obtained via a stick-slip mechanism, and steps as small as 10 nm are obtained. A displacement speed of 0.4 mm/s has been attained, and the device was capable of carrying several times its own weight, exerting a horizontal force, or climbing a plane inclined by 7°. Due to its compact construction, the device shows prospects for miniaturization.
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    URL: http://dx.doi.org/10.1063/1.1140206
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    Comparison between time-of-flight spectra measured at a spallation source and at a high flux reactor (1988)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 59 (1988), S. 370-371 
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    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: We give a comparison for inelastic neutron scattering experiments performed at the high flux reactor in Grenoble and at the spallation source in Argonne. These experiments were performed at the IN4 (I. L. L. Grenoble) and at the HRMECS (IPNS Argonne) with nearly identical conditions using E0(approximately-equal-to)50 meV as energy of incident neutrons. We conclude that the neutron counting rate for a given scattering angle is less by a factor of about 30 at HRMECS than at IN4. This is due to a rather small neutron flux at HRMECS. Thus the background to signal ratio is worse by a factor of 2 at HRMECS compared to IN4.
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    URL: http://dx.doi.org/10.1063/1.1140207
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    Versatile Raman spectrometer control with the IBM-PC/XT (1988)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 59 (1988), S. 376-378 
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    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: The scan drive of a stepper motor, signal detection and data processing of the recorded Raman signals were controlled by a compatible IBM-PC/XT which was connected to a Jarrell–Ash 25-400 spectrometer. Excitation source fluctuations were eliminated by the simultaneous detection of a small portion of laser light. This reference and the Raman signals were transmitted to the 8-bit parallel port of the IBM by multiplexing. The parallel port was modified to bidirectional data transfer so that control and signal processing required only one port.
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    URL: http://dx.doi.org/10.1063/1.1140210
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    Neutron imaging of inertial confinement fusion targets at Nova (1988)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 59 (1988), S. 1694-1696 
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    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: Images of the neutron-emitting region of high-yield inertial confinement fusion targets have been obtained with a penumbral coded-aperture imaging system. The major components of the imaging system are the penumbral aperture, neutron detector, alignment hardware, and image reconstruction software. We describe these components and present an example of the neutron imaging results.
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    URL: http://dx.doi.org/10.1063/1.1140136
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    Measurements with vertically viewing charge exchange analyzers during ion cyclotron range of frequencies heating in TFTR (1988)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 59 (1988), S. 1691-1693 
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    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: The utility of charge exchange neutral particle analyzers for studying energetic ion distributions in high-temperature plasmas has been demonstrated in a variety of tokamak experiments. Power deposition profiles have been estimated in the Princeton large torus (PLT) from particle measurements as a function of energy and angle during heating in the ion cyclotron range of frequencies (ICRF) and extensive studies of this heating mode are planned for the upcoming operational period in the tokamak fusion test reactor (TFTR). Unlike the horizontally scanning analyzer on PLT, the TFTR system consists of vertical sightlines intersecting a poloidal cross section of the plasma. A bounce-averaged Fokker–Planck program, which includes a quasilinear operator to calculate ICRF-generated energetic ions, is used to simulate the charge exchange flux expected during fundamental hydrogen heating. These sightlines also cross the trajectory of a diagnostic neutral beam (DNB), and it may be possible to observe the fast ion tail during 3He minority heating, if the DNB is operated in helium for double charge exchange neutralization.
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    Neutron emission time measurements for ICF targets (1988)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 59 (1988), S. 1697-1699 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: The neutron emission time for laser-driven inertial confinement fusion targets is determined from data recorded with fast neutron and optical detector systems. Two types of neutron detectors are used. Radiation-induced conductivity devices have a 130-ps FWHM response and are sensitive to targets with yields greater than 5×1010 DT neutrons. They measure the average neutron emission time with a precision of ±50 ps and are fast enough to measure the neutron production rate within a target core as a function of time. Plastic scintillators coupled to microchannel-plate photomultiplier tubes have a 1.2-ns FWHM response and measure the average neutron emission time with a precision of ±75 ps for targets with yields greater than 106 neutrons. Streak cameras record the incident laser power. Optical fiducial signals that are injected into each detector are used to cross time between the detector systems. Measurements made on 1-mm-diam spherical targets irradiated with 23 kJ of 0.35-μm light delivered in a temporally square 1.1-ns pulse and yielding 1013 neutrons show a burn duration greater than 300 ps and an average neutron emission time of about 850 ps.
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    URL: http://dx.doi.org/10.1063/1.1140137
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    Performance of a microscopic imaging ellipsometer (1988)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 59 (1988), S. 2557-2559 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: A microscopic imaging ellipsometer has been constructed based on use of a CCD camera and framegrabber board in a PC computer. The performance (sensitivity and speed) are described.
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    URL: http://dx.doi.org/10.1063/1.1139897
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    Longitudinal discharge N2 laser with automatic preionization using an LC inversion circuit (1988)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 59 (1988), S. 2552-2556 
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    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: A four-segmented longitudinal discharge low pressure N2 laser (337 nm) is reported in which automatic spark preionization and an LC inversion-charge transfer excitation circuit are employed. Its laser output power was nearly doubled when the techniques developed here were used. The characteristics of the peak laser output powers are interpreted qualitatively, with the electron densities calculated from the observed discharge voltages and currents.
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    URL: http://dx.doi.org/10.1063/1.1139896
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    Calibration of the TFTR neutron activation system (1988)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 59 (1988), S. 1715-1717 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: Neutron generators, both D–D and D–T, have been used to calibrate the TFTR neutron activation (NA) system for point sources located within the tokamak. The foils used were In for D–D neutrons and Cu, Al, and 238U for D–T neutrons. Delayed neutrons following fission were counted when using 238U foils, 336-keV γ rays from 115In(n,n')115m In reactions, annihilation radiation from 62Cu following the 63Cu(n,2n)62Cu reaction, and 1368- and 2754-keV γ rays from the 27Al(n,α)24Na reaction. Large effects caused by source anisotropy and local machine structure were observed. These effects and the attempts to accommodate them in the data analysis will be described.
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    URL: http://dx.doi.org/10.1063/1.1140143
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    Calibration of a surface barrier detector for 14-MeV neutron flux measurements on TFTR (1988)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 59 (1988), S. 1718-1720 
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    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: Nuclear reactions in silicon semiconductor detectors with an energy threshold above 2.5 MeV can be used to measure dt neutrons in a high background of low-energy dd neutrons. This allows the measurement of 14-MeV neutrons from the d(t, n)α reaction in deuterium plasmas, where the tritons from the d(d, t)p reaction create 14-MeV neutrons due to burnup. Measurements with a surface barrier detector are presented together with the calibration of such a detector to measure the absolute 14-MeV neutron source strength.
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    URL: http://dx.doi.org/10.1063/1.1140144
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    Broadband microwave absorption spectrometer for liquid media (1988)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 59 (1988), S. 2577-2582 
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    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: A broadband, continuous-sweep microwave spectrometer has been constructed for measurements of the absorption coefficient of aqueous solutions and other liquid media. The spectrometer makes use of the phase fluctuation optical heterodyne technique, which provides a direct measure of the microwave power deposited in the sample. Consequently, in contrast to the standard dielectrometric techniques that indirectly determine the absorption coefficient via separate measurements of the real and imaginary parts of the dielectric constant, this spectrometer directly measures the microwave absorption coefficient. Broadband spectra are obtained using a transmission line to couple microwave power into the liquid sample. The absorption spectrum for deionized water in the range 3–20 GHz is presented as an example and shows excellent agreement with calculated values of the absorption coefficient based on previously published dielectric data.
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    URL: http://dx.doi.org/10.1063/1.1139901
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    Study of pressure distributions in a megabar diamond indentor cell (1988)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 59 (1988), S. 2583-2591 
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    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: We have studied pressure distributions and area of contact as a function of load in a diamond indentor cell consisting of a flat diamond plate and diamond indentors of two different radii of curvature. The measurements were conducted with type Ia, IIa, and uncharacterized diamonds. Samples investigated were either ruby or ruby on a tantalum foil. In both cases, the ruby fluorescence was used to determine the pressure distributions. Previous suggestions that the elastic Hertzian solutions are applicable for plastic samples are not supported by these data. We conclude with comments on the prospects of the system for experimental high-pressure research.
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    URL: http://dx.doi.org/10.1063/1.1139902
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    Diamond anvil cell and loading system for liquid CO2 (1988)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 59 (1988), S. 2592-2595 
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    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: A diamond anvil cell designed for optical experiments at low temperatures is described. The design is focused on alignment stability and accurate pressure adjustment. To fill the cell with liquid CO2 a special technique is employed, combining features from high-pressure and cryogenic-loading procedures. The method has a short cycle time and does not require the use of gas compressors.
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    URL: http://dx.doi.org/10.1063/1.1139903
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    Heated cell for electron beam pumped VUV experiments (1988)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 59 (1988), S. 2596-2599 
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    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: The design of a high-temperature cell appropriate for electron beam pumping of species emitting in the vacuum ultraviolet is described. The apparatus is capable of maintaining a temperature as high as 750 °C at a cell pressure of up to 6 atm which is suitable for a variety of investigations of atomic and molecular vapors, such as alkali metals and alkali-metal, rare-gas mixtures. The performance of this apparatus with rubidium vapor in a buffer gas is described.
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    URL: http://dx.doi.org/10.1063/1.1139904
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    Design of the TFTR rf probe array (abstract) (1988)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 59 (1988), S. 1890-1890 
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    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: A new diagnostic, composed of an array of high-frequency magnetic probes, has been installed in TFTR for the study of waves driven by the ICRF heating antennas and waves generated spontaneously during ohmic and beam-heated discharges. The former is of interest because of the possibility of surface wave generation by the heating antennas, and the latter because emission spectra may be useful as a beam ion or fusion product diagnostic. The array consists of seven fixed probes positioned at various toroidal and poloidal locations in order to obtain information about the corresponding wavenumbers in the edge region. Each probe consists of two orthogonal loops oriented to measure Bφ and Bθ. The array utilizes single-turn loops with areas of 12 cm2 and carefully selected signal processing elements to achieve a usable bandwidth of 1–500 MHz. Reduction of electrostatic pickup is accomplished by differentially combining signals from both ends of a loop using a wideband hybrid junction and by using an alumina shield to reduce capacitive coupling. The system permits simultaneous observation of both the magnetic and electrostatic components of the probe signal, allowing verification of the rejection ratio in a particular experiment. Details of the diagnostic design and experimental plans are discussed. This work was supported by U. S. DOE Contract No. DE-AC02-76-CHO-3073.
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    In-situ monitoring of redeposited carbon in the vicinity of a plasma–graphite interacting region (abstract) (1988)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 59 (1988), S. 1891-1891 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: The interaction of the plasma with graphite limiters in fusion devices has been observed to lead to the formation of carbon film deposits. This occurs from the erosion of the graphite tiles in a high-flux region and subsequent redeposition of the carbon atoms onto a low-flux surface. The redeposition of carbon has strong ramifications on the in-vessel tritium inventory. A commercially available quartz crystal monitor has been tested in a plasma simulator device to measure the flux of eroded carbon. The test was done with the intent of mounting such a detector in TFTR. The monitor measures the deposited film thickness as a change in the resonance frequency of the crystal. The plasma simulator is a Penning discharge operated with graphite electrodes. Initial tests show the crystal monitor has high sensitivity and can detect film thickness changes of a few angstroms. Thermal shock problems, however, may limit time resolution of the measurement and can provide only an integrated deposited thickness within a discharge. This work was supported by the U. S. DOE.
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    Null input current SQUID magnetometer for the measurement of the transition temperature of high-Tc superconducting samples (1988)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 59 (1988), S. 1031-1034 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: In this article we describe a SQUID-based system used to measure the superconducting transition temperature in the range 4.2–300 K. The apparatus has been tested using a high-critical-temperature single crystal of YBa2 Cu3 O7−x ((approximately-equal-to) 10−1 mm3 volume). The system is based on mutual inductance variations measurements, performed in a low-frequency ac magnetic field of 2×10−5 T. A feedback loop is closed on the input circuit in order to null out the current flowing in the pickup coil. This is achieved using an electronic scheme which does not involve any modification of the commercial SQUID electronics. Our experiment is performed using a copper wire pickup coil, but the scheme can also be used with a superconducting input circuit, thus allowing measurements in a dc regime. The obtained sensitivity is 5×10−5/(square root of)Hz. This figure can be further improved by optimizing the circuit parameters.
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    Compact, high-stability, "thimble-size'' scanning tunneling microscope (1988)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 59 (1988), S. 1035-1038 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: A new high-stability scanning tunneling microscope (STM) has been developed. Its key design feature is the application of two, concentrically aligned, piezoelectric ceramic tubes, allowing x–y–z motion of the tungsten tip as well as sample mounting to be cast into a single compact unit. The construction is small, very rigid, and temperature compensated, yielding reduced sensitivity to mechanical and acoustic vibrations and temperature variations. Other advantages of this "thimble-size'' STM include easy sample mounting and, at a later stage, operation under UHV conditions with access to other surface-analysis (UHV) tools. At present, the microscope is operated in air, and its performance is tested by imaging a highly oriented pyrolytic graphite surface and a Si(111) surface on which a 100-A(ring)-thick Au layer has been deposited.
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    Characterization of a cesium surface ionization source with a porous tungsten ionizer. I (1988)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 59 (1988), S. 1039-1044 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: A cesium surface ionization source of the type and geometry customarily used in conjunction with sputter-type negative heavy ion sources has been characterized. Measurements have been made of positive-ion production and probabilities of ionization as functions of extraction voltage and cesium oven temperature for ionizer porosities of 0.7 and 0.8. The perveance P of the source, when operated in the space-charge-limited regime with the ρ=0.7ρ0 ionizer, is found from experiment to be 7.61×10−4 μP, while that for the ρ=0.8ρ0 ionizer is 1.92×10−4 μP. These values are lower by factors of 3.88 and 15.53, respectively, than those predicted by numerical solution to Poisson's equation for full area emission from the source. Positive-ion current versus ionizer temperature data are also presented along with mechanical design features of the source.
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    Aspects of negative-ion generation and extraction from a refocus geometry cesium sputter negative-ion source. II (1988)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 59 (1988), S. 1045-1052 
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    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: The basic parameters of the refocus geometry cesium sputter ion source for the production of negative ions from a low-sputtering material (carbon) and a high-sputtering material (copper) have been measured. The question of the influence of sample temperature on the negative-ion generation process has been addressed. Negative-ion yields from carbon samples are found to be weakly dependent on temperature over a range from 26° to 400 °C, while those from copper samples are found to be essentially independent of temperature over a range of 26° to 200 °C. The results of these investigations indicate that (1) sample temperature does not strongly influence negative formation in these sources, and (2) the maximum negative-ion yields for a given sample are dependent on both cesium-ion energy and positive-ion current. In addition to these data, the negative-ion extraction optics of the source are briefly discussed and cursory estimates of the probabilities for negative-ion formation presented.
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    URL: http://dx.doi.org/10.1063/1.1139777
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    Novel Langmuir probe technique for the real-time measurement of the electron temperature (1988)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 59 (1988), S. 1053-1056 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: A new method for the evaluation of the electron temperature from the voltage–current characteristic of a single Langmuir probe under the application of an ac signal was developed and tested. This method exploits harmonics in the current spectrum which arise from the nonlinearity of the characteristic; from the amplitude of these harmonics the electron temperature can be deduced. Langmuir probe measurements on the TEXTOR edge plasma show a good agreement of the new method with the conventional one. The advantages of this method over other methods are discussed. Proposals for further improvements are given.
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    Measurement of large displacements of the toroidal current centroid using an external coil diagnostic (1988)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 59 (1988), S. 1057-1062 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: Several sinusoidal and saddle coils have been used to measure the toroidal current centroid of discharges produced in a pulsed tokamak experiment. Careful analysis of the external coil measurements and elaborate calibrations made the measurements possible even for large displacements of the plasma current and the noncircular geometry of the diagnostic coils. The calibration techniques and the data analysis formula are described, and examples of the use of the external coils to measure m=1 kinks of unstable toroidal Z-pinch discharges are presented.
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    Infrared thermography of the DIII-D divertor targets (1988)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 59 (1988), S. 1878-1880 
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    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: The power flow to the DIII-D divertor targets is routinely measured using infrared (IR) thermography. An IR television camera sensitive to radiation in the 8–12-μm range views the divertor region using a set of germanium optics. Digital signal processing is used to extract the desired surface temperature profiles from the analog data ((approximately-equal-to)12 Mbytes) stored on videotape. Inversion of these data using a simple matrix formulation of the inverse heat conduction problem then yields the incident heat flux as a function of space and time. Results from a DIII-D discharge are included.
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    Preparation of TFTR diagnostics for D–T break-even experiments (1988)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 59 (1988), S. 1881-1883 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: Although diagnostic systems for the tokamak fusion test reactor (TFTR) must be compatible with high-power experiments in deuterium–tritium (D–T) plasmas, it has been neither possible nor desirable to implement all the required features during the early phases of the facility. The research plan, the physical plant, instrumentation, and diagnostic techniques have all evolved during the past decade, and some of the original plans are no longer suitable. Preparations are now underway for D–T operation in TFTR in 1990. Among the activities necessary in support of the research plan are completion of the installation of the D–T diagnostic set, modification of diagnostic hardware to accommodate the "igloo'' radiation shield of the torus, installation of auxiliary shielding for detectors and electronics, and enhancement of the reliability of specific components. These preparations and the final D–T diagnostic set for TFTR will be described.
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    Transient space charge limited current spectroscopy method of measuring the position and concentration of trap levels in semi-insulating materials (1988)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 59 (1988), S. 2468-2470 
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    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: A new method is reported to measure the position and concentration of trap levels in semi-insulating materials where the regular deep level transient spectroscopy method is not applicable. In the proposed method, a transient space charge limited current (TSCLC) associated with the trap levels is measured using a capacitance balanced square wave voltage source, a voltage limiter-amplifier and a double box car averager. The TSCLC method is demonstrated on a p-type Y2.01Ca0.99Ge0.91Fe4.09O12 magnetic garnet sample ρ300=107 Ω cm. The trap level is located at 0.36 eV above the valence band edge and the concentration of the trapped holes is found to be 1013–1015 cm−3.
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    Ripple method: An application of the square-wave excitation method for heat-capacity measurements (1988)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 59 (1988), S. 1176-1181 
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    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: An extension of the square-wave excitation method for measuring heat capacity is reported. In particular, attention is focused on the limit where the period of the heat pulse excitation is much smaller than the thermal relaxation time of the calorimeter-sample system. In this limit, one finds that the thermal ripple induced by the heat pulse is inversely proportional to the heat capacity. This technique allows one to do real-time heat-capacity measurements as in the conventional ac technique with the same instrumentation as the square-wave method. The ripple method is demonstrated with a measurement of the heat capacity of strained Al near its superconducting phase transition.
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    Low-cost calorimeter for simulating shape memory effect heat engines (1988)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 59 (1988), S. 1169-1175 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: A novel, inexpensive calorimetry system is described for the analysis of the specific heat anomalies of shape memory effect (SME) alloys cycled through the martensitic transformation. By loading the sample on heating through the martensitic to austenitic transformation and unloading on cooling through the reverse transformation, a typical SME heat engine cycle is simulated. Analysis of the specific-heat anomalies from these simulations gives a direct measure of the thermal efficiencies of the SME alloy. The requirements of externally stressing the sample as well as a changing sample shape produced heat losses which were difficult to estimate. An algorithm is described which estimates the combined heat losses by thermal base-line subtraction. Measurements of the specific heats and enthalpies of transformation for heating and cooling through the transformations are presented, from which the thermal efficiencies were calculated.
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    Technique for measurement of resistivity versus simultaneous temperature and pressure in a tetrahedral anvil press (1988)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 59 (1988), S. 2479-2482 
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    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: Electrical resistivity measurements of materials as a function of pressure and temperature simultaneously are valuable indicators of structural phase changes and of electronic properties. Such measurements are difficult, however, and relatively few materials have been studied in this way. A sample holder for a tetrahedral anvil apparatus has been modified so that such measurements may be made. The calibration of the Pt/Pt10Rh thermocouple used to determine the temperature of the sample was found to be affected by pressure, and preliminary recalibration of this thermocouple under pressure was performed. Reasonable agreement was found between the phase diagram of CdTe determined with the apparatus used in this study and that previously published.
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    Inexpensive home computer used as a versatile digital delay generator (1988)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 59 (1988), S. 2499-2500 
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    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: A versatile digital delay generator is described which is built using the widely available C64 Commodore home computer. Fixed delays and delay scans from 1 μs up to 65 ms with 1-μs step size are possible. One can modify the generator program; for instance, a delay scan followed by a number of fixed delay sequences. The speed of a delay scan is adjustable over a very wide range and the accuracy of the delay generation depends uniquely on the system clock accuracy.
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    URL: http://dx.doi.org/10.1063/1.1139886
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    A high-voltage, short-risetime pulse generator based on a ferrite pulse sharpener (1988)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 59 (1988), S. 2497-2498 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: A high-voltage, short-risetime pulse generator is described. The generator consists of a Marx bank, which produces an initial high-voltage pulse, and a ferrite pulse sharpener that reduces the risetime of the pulse. The generator delivers 70-kV, 350-ps risetime pulses into a 50-Ω load.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1139937
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  • 79
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    Chromatic time lag in picosecond-streak-camera objectives (1988)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 59 (1988), S. 2502-2503 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: Wavelength-dependent time lags due to group velocity dispersion (GVD)—much larger than estimated and documented thus far—have been determined experimentally for some widely used streak camera objectives. Correction procedures for signals delayed and broadened by group dispersion in streak camera objectives are briefly outlined.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1139888
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    Comment on "Mass analyzed secondary ion microscopy'' [Rev. Sci. Instrum. 58, 1789 (1987)] (1988)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 59 (1988), S. 2508-2509 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: A review article in the October 1987 issue of the Review of Scientific Instruments entitled: "Mass analyzed secondary ion microscopy,'' by Mark T. Bernius and George H. Morrison, contains a number of incorrect statements and quotations that must be rectified. A table comparing the UC scanning ion microprobe and the Cornell stigmatic ion microscope is presented.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1139891
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  • 81
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    Endoscopic fluorescence detector (1988)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 59 (1988), S. 930-933 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: This instrument, working in conjunction with standard clinical endoscopes, detects the fluorescence of hematoporphyrin derivative accumulated in tumors. At the same time, the operator receives a conventional image of the target and a signal indicating the intensity of fluorescence. Owing to the simultaneous measurement of fluorescence and backscattered excitation light as a reference, the dependence of this signal on the target vascularization, the target-endoscope distance, and the viewing angle is strongly reduced over a wide range of these parameters.
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    URL: http://dx.doi.org/10.1063/1.1139752
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  • 82
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    Automatic integrating fluorometer using an Apple-II and Scope-85 (1988)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 59 (1988), S. 934-936 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: The system presented here measures the fluorescence of plant samples in in vivo and in vitro automatically, calculating the principal photosynthetic parameters of the sample (evaluation of the F0 level of fluorescence, normalization of the fluorescence curve, rate of light trapped at the PSII complex, maximum quantum yield of photochemistry, average fluorescence induction time, and evaluation of the number of PSII reaction centers) as well as measuring heat dissipation kinetics. Because this system offers higher speed, more versatility, and greater accuracy (3%) than manual methods, it is a unique and valuable tool for laboratories involved in fluorescence research in the photosynthesis field. To demonstrate the use of this system and its superior performance, this article describes classic experiments carried out with the alga Dunaliella tertiolecta.
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    URL: http://dx.doi.org/10.1063/1.1139753
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  • 83
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    Plasma density measurement using a simple microwave technique (1988)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 59 (1988), S. 2149-2151 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: We describe a simple method of determining the plasma density unambiguously with the help of a microwave interferometer. The frequency of the Klystron source is modulated with the help of a staircase voltage pulse. The height of each staircase is adjusted in such a way that the corresponding phase shift is 90°. Signals proportional to the cosine and sine of the phase shift due to plasma are generated, and the plasma density is unambiguously measured. The advantages of the method are highlighted in the text.
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    URL: http://dx.doi.org/10.1063/1.1139977
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  • 84
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    Measurement of Seebeck coefficient using a large thermal gradient (1988)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 59 (1988), S. 951-954 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: The integral method of measuring the Seebeck voltage V(T), in which one end of the sample is held at a fixed temperature TC, and the other end is varied through the temperature T range of interest, has been adapted to short rod-shaped samples. The Seebeck coefficient S is obtained from the slope of the V(T) vs T curve, i.e., S=dV(T)/dT. The apparatus has been completely automated such that the specimen is automatically cycled through a preselected temperature range, up to a maximum temperature of 1000 °C, and the V(T), T, and TC values are acquired, stored, and analyzed by means of a microcomputer. Simplicity of sample handling and minimal operator involvement make this method well suited to the survey of large numbers of samples.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1139756
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  • 85
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    Experimental apparatus for measuring noise in MOSFETs on silicon wafers (1988)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 59 (1988), S. 955-959 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: We present an apparatus for measuring noise in MOSFETs on silicon wafers. The system can measure noise accurately down to 10 nV/Hz1/2 and has a useful bandwidth of 0.01 Hz to 30 kHz. The drain current, source voltage, gate voltage, and the temperature (77 to 400 K) are computer controlled. We have designed a chip with both N and P channel test transistors in a range of sizes and geometries. The chip also includes a diode for temperature measurement. The wafers are processed in a controlled industrial environment giving reproducible device characteristics. Schematics for an ADC-DAC high-performance card offering many programmable features are also presented. A very-low-noise preamplifier working at liquid-nitrogen temperature is also described. The system is not restricted to measuring MOS transistors; any passive or active device can be measured making only simple changes to the bias circuitry. We also present results obtained with a typical MOSFET.
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    URL: http://dx.doi.org/10.1063/1.1139757
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  • 86
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    Robotic work station for microscale synthetic chemistry: On-line absorption spectroscopy, quantitative automated thin-layer chromatography, and multiple reactions in parallel (1988)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 59 (1988), S. 940-950 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: A robotic work station has been constructed for automatically initiating and monitoring microscale chemical reactions. The work station consists of a robot with a general-purpose arm and interchangeable special-purpose hands, a carousel of seven reaction vessels, a series of stations for performing quantitative automated thin-layer chromatography (TLC), an on-line multichannel absorption spectrophotometer, sensors for verification, syringes and pumps for sample and solvent delivery, a supervisory computer for real-time data acquisition and process control, and a graphics terminal for data display. The controlling software is menu-driven and contains a scheduling algorithm that permits multiple reactions to be performed simultaneously. The automated TLC process is performed in four stages (plate dispensing, sample application, plate development, and plate densitometry), and samples are moved sequentially among these stations by the robot. The partial autonomy of these separate stations permits distributed sample processing. Four TLC plates are processed simultaneously with interleaving segmented schedules, giving a 160% increase in TLC sample throughput. The workstation can be applied to yield optimizations of synthetic reactions and to the exploration of synthetic reaction spaces. The capabilities of the workstation are demonstrated in the two-step synthesis of tetraphenylporphyrin from benzaldehyde and pyrrole in 1 h at room temperature. Kinetic data are obtained from a single-batch reaction concerning the consumption of benzaldehyde, the side reactions forming dipyrrylmethenes, and the formation of tetraphenylporphyrin.
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    URL: http://dx.doi.org/10.1063/1.1139755
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  • 87
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    Characterization of a simple, high Reynolds number droplet generator for combustion studies (1988)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 59 (1988), S. 960-966 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: A new technique is described for generating droplets in the size range between 240 and 750 μm. The droplets are characterized by Reynolds numbers (in air at standard conditions) greater than 100, hence, with a liquid fuel as the droplet fluid, this technique has applicability in studies of convective droplet burning. The concept behind the technique is simple. A capillary tube is employed to deposit a droplet in the center of a flight tube. Gas flow through this tube detaches the droplet from the capillary, and the droplet accelerates down the tube. Droplets remain stable in the tube for tube diameters of 1.5 to 3 times the droplet diameter. Generation rate is dependent on the liquid flow rate through the capillary and can be varied sufficiently to produce droplets at a rate between 1 and 100 per second. Exit velocities are reported as a function of droplet size for a variety of flight tube lengths and diameters. Water was used in all experiments reported here, but no difficulty should arise in using the technique to produce liquid fuel droplets. The largest droplet generated was 750 μm with an exit velocity of 3.5 m/s yielding a Reynolds number of 175. The smallest droplet produced was 240 μm with an exit velocity of 11 m/s yielding a Reynolds number of 165. The highest Reynolds number achieved in this work, 371, was obtained with a droplet size of 390 μm and an exit velocity of 14.3 m/s. Decreasing the droplet size while increasing exit velocity should be possible.
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    URL: http://dx.doi.org/10.1063/1.1139758
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    Method for measurement of viscosity and density of liquid with a slowly rotating column (1988)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 59 (1988), S. 967-970 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: The locus of a fine spherical particle in a slowly rotating column filled with liquid is investigated in detail with a fundamental equation of motion, and a method for measurements of viscosity η and density ρ' of the liquid is proposed. With a particle having the radius a=10−3–10−2 cm from the restriction Re(approximately-less-than)1, (Re, Reynolds number) and the density ρ within 1.5ρ'(approximately-less-than)ρ〈4ρ' in a column rotating at the angular velocity ω0 within 1.5(approximately-less-than)Aω0/V0〈2, the particle locus becomes almost a circle with a diameter D that sensitively correlates with η and ρ' to be measured, where A=A0−a (A0, column radius) and V0 is the speed at free fall. For one particle (a one-particle system), η is universally measurable for almost any kind of liquid with a known ρ'. A two-particle system is also proposed for the continuous measurement of both η and ρ', and would be applied, for example, at varying temperatures or in the course of a chemical reaction.
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    URL: http://dx.doi.org/10.1063/1.1139759
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  • 89
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    Low-pass filter in flux transformer circuits for SQUID magnetometers (1988)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 59 (1988), S. 971-972 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: In order to eliminate extraneous alternating fields in magnetic field measuring setups using SQUID magnetometers, a compensating network has been developed which exhibits low-pass filter characteristics. Guidelines will be given for the optimal parameters of such circuits. On the basis of a network realized with a corner frequency of 1 Hz and with a stop-band attenuation of about 20 dB the reason why the theoretically total compensation is not achievable in practice is attributed to mismatched components and to eddy currents in the Dewar walls.
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    URL: http://dx.doi.org/10.1063/1.1139760
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  • 90
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    Charged-particle imaging video monitor system (1988)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 59 (1988), S. 2206-2210 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: A charged-particle imaging video monitor system was constructed for video imaging of the distributions of alpha-emitting and low-energy beta-emitting nuclides. The imaging video monitor system consists of a detector head, a silicon intensifier target (SIT) camera, a video frame memory, and a personal computer. The system can display not only the scintillation image due to radiation on the video monitor, but also the integrated video image becoming gradually clearer on another video monitor. The integrated image is transferred to a personal computer for image processing. The distortion of the image is about 5%, and the spatial resolution is about 2 line pairs (lp) mm−1.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1139988
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  • 91
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    Auroral height-measuring system designed for real-time operation (1988)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 59 (1988), S. 2211-2219 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: The altitude and altitude distribution of auroral emissions, such as the [N+2] λ427.8-nm emission, are one result of processes in the ionosphere and magnetosphere during periods of auroral activity. A bistatic height-measuring system (HMS) has been developed with the primary objective of determining the altitude and latitude of auroral emissions in the magnetic meridian plane through Kiruna, Sweden. Since significant morphological redistributions occur in the aurora within a few seconds, HMS was designed to measure auroral altitudes with a time resolution of 1.5 s. The base line between the two stations was short (13 km), which generated similar-looking meridian profiles of the measured auroral emissions. The meridian profiles were obtained with intensified photodiode arrays, operated in a monochromatic imaging mode. The hardware and software configurations of HMS and essential assumptions for the triangulation procedure are described. HMS is especially adapted to measure during periods of disturbances in auroral arcs, e.g., eastward-traveling folds. The estimated optimal accuracies of the determinations of the latitudinal position of an auroral arc and the altitude of an identified auroral point are ±0.01° and ±1 km, respectively.
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    URL: http://dx.doi.org/10.1063/1.1139989
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    Hybrid clock oscillator modules as deposition monitors (1988)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 59 (1988), S. 983-986 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: The construction of an inexpensive vacuum deposition monitor made from commercially available hybrid quartz-crystal oscillator modules is described. The monitor is intended for use in odd-job vapor-plating applications. The design, however, has distinct advantages over conventional deposition monitors which suggests that it might have broader applications. Both the sensor crystal and its oscillator and the reference oscillator are placed together in the vacuum system. Thermal gradients and capacitance variations which potentially limit the sensitivity of the system are eliminated. Even without water cooling at deposition rates approaching 45 A(ring)/s and deposition times exceeding 100 s a linear response for the monitor is observed.
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    URL: http://dx.doi.org/10.1063/1.1139764
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    Transmission characteristics of a triple quadrupole mass spectrometer with leaky dielectric end plates (1988)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 59 (1988), S. 987-989 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: The use of a rf-only quadrupole in tandem with a normal resolving quadrupole introduces artifacts in the mass spectra obtained using such an instrument. The reason for this is the presence of fringe fields in the region between the two quadrupoles. We report here the use of leaky dielectric material in between the two quadrupoles to avoid these artifacts.
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    URL: http://dx.doi.org/10.1063/1.1139765
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    New ultrahigh-vacuum cleaver for brittle materials (1988)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 59 (1988), S. 989-990 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: In materials research it is often necessary to cleave brittle materials, such as semiconductors, in order to perform experiments on clean surfaces. This note presents the design of an ultrahigh-vacuum cleaving tool which can yield crystal surfaces of very high quality.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1139766
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    High-sensitivity small size mirror mount (1988)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 59 (1988), S. 990-991 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: A small size mirror mount is described, whose high sensitivity is obtained by the use of coaxial differential screws.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1139767
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    Velocity and moving angle measurements of solid surfaces by simple velocimetry (1988)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 59 (1988), S. 993-995 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: A simple laser Doppler velocimeter constructed for measuring the velocity and moving angle of a moving surface simultaneously is described. This instrument accomplished two-component velocity measurement for a solid surface by using the characteristic of specular reflection of the solid surface.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1139769
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    Measuring sound velocities along release adiabats with Manganin stress gauges (1988)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 59 (1988), S. 991-993 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: We propose a new technique to measure the state of shock-loaded specimens along their release adiabats. The technique is based on symmetric impacts of equal thickness flyer and target disks. A Manganin stress gauge is embedded at the back of the target and backed by a thick Plexiglas disk. The stresses at the specimen–Plexiglas interface are relieved in a stepwise manner which is typical for this type of experiment. From the time duration between consecutive release waves one can determine the sound speed in the released specimen. Drastic changes in sound speed, as in melting, can be detected by these time durations adding more information on the state of the specimen as it unloads from very high shock stresses.
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    URL: http://dx.doi.org/10.1063/1.1139768
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    Improved hot-wire procedure for thermophysical measurements under pressure (1988)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 59 (1988), S. 2269-2275 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: A new and simplified version of the circuitry for the transient hot-wire method is presented. The circuitry provides a wide range of currents allowing probe wires of various diameters to be used in order to match the thermal properties of the specimen to be investigated. The analysis of the temperature increase during the heat pulse is based on the exact solution for a heated wire immersed in a medium. Data are corrected for varying power. The method was tested by computer simulations and by measurements of the thermal conductivity (λ) and the heat capacity per unit volume (ρcp ) of glycerol at room temperature and atmospheric pressure, and for CsCl and NaCl at room temperature and at pressures up to 2 GPa. The results on glycerol and CsCl are in excellent agreement with previous works. The inaccuracy in λ and ρcp is estimated as 1%–2% and 3%–5%, respectively, but the standard deviation of the measurements is as low as 0.2% for λ and 1% for ρcp. The improved procedure makes it possible to detect systematic errors caused by reflection of the heat pulse from the walls of the high-pressure cell. This error, which reveals itself by a curvature of the residual, defined as the difference between fitted function and data, was demonstrated in the case of NaCl. A theoretical estimate of the influence of perturbations due to reflection was also carried out and it was found that the error mainly affects the value of ρcp.
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    URL: http://dx.doi.org/10.1063/1.1139946
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    A superconducting coaxial transmission line for dilution refrigerators (1988)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 59 (1988), S. 2276-2278 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: A novel helium-gas-filled coaxial insert sealed with ceramic feedthroughs, which thermally grounds the superconducting niobium inner conductor of a coaxial transmission line at the 1.3-K pot of a dilution refrigerator, is described. This transmission line–insert combination overcomes the large heat leak associated with room temperature coaxial access to a dilution refrigerator and results in relatively unperturbed broadband transmission of radio-frequencies from room temperature to the mixing chamber, with a heat load of less than 1 μW. Two such lines are used to access a cw NMR system incorporated in an Oxford Instruments model 200 top-loading dilution refrigerator, resulting in a rise of the base temperature from 10 mK up to 12 mK. The thermal impedance of the insert with and without helium is analyzed between 1.5 and 6 K; it is shown that the heat leak can be further reduced by an order of magnitude with relatively minor modifications.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1139947
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    Improved bolometry system for reversed field pinch research (1988)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 59 (1988), S. 700-708 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: A bolometry system for time and spatially resolved energy-loss measurements on the ZT-40M reversed-field pinch is described. This system allows ∼100-μs time resolution with a radiation detection limit of ∼100 mW/cm2 , in particularly noisy electromagnetic environments. The bolometer element fabrication using evaporative techniques and photolithography is discussed. Increased noise rejection is realized by using an oscillator/FM receiver electronics system based on 5-MHz ac excitation of the resistor. An improved oscillator is described. Because resistive sensing is done at 5 MHz, pulsed heating currents may simultaneously be passed through the bolometer resistor and this allows for absolute in situ system calibration. We describe a new method of such calibration that is independent of the resistor geometry.
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    URL: http://dx.doi.org/10.1063/1.1139813
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