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  • 1
    Electronic Resource
    Electronic Resource
    Ultrafast transient absorption measurement of the electron-LO phonon scattering time in GaAs-Al0.33Ga0.67As multiple quantum wells (1994)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 64 (1994), S. 889-891 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The electron-LO phonon scattering time in GaAs-Al0.33Ga0.67As quantum wells is determined to be 200±50 fs using transient absorption with low excitation density, a more direct method than previous measurement techniques.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.110986
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  • 2
    Electronic Resource
    Electronic Resource
    Plasma-anode electron gun (1994)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 76 (1994), S. 5629-5635 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The plasma-anode electron gun (PAG) is an electron source in which the thermionic cathode is replaced with a cold, secondary-electron-emitting electrode. Electron emission is stimulated by bombarding the cathode with high-energy ions. Ions are injected into the high-voltage gap through a gridded structure from a plasma source (gas pressure ≤50 mTorr) that is embedded in the anode electrode. The gridded structure serves as both a cathode for the plasma discharge and as an anode for the PAG. The beam current is modulated at near ground potential by modulating the plasma source, eliminating the need for a high-voltage modulator system. During laboratory tests, the PAG has demonstrated square-wave, 17-μs-long beam pulses at 100 kV and 10 A, and it has operated stably at 70 kV and 2.5 A for 210 μs pulse lengths without gap closure.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.357068
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  • 3
    Electronic Resource
    Electronic Resource
    Microwave/millimeter-wave generation in a counterstreaming-beam-plasma system (1993)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 74 (1993), S. 3057-3060 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Radiation from 8 to 60 GHz is generated by injecting counterstreaming, high-power (up to 50 keV and 4 A) electron beams into an unmagnetized, plasma-loaded waveguide. The radiation is emitted at twice the plasma frequency and is amplitude modulated on the ion plasma frequency time scale. The beam-to-millimeter-wave power conversion efficiency at 31 GHz is (approximately-greater-than)0.04%. A turbulence theory model is consistent with the radiation characteristics and power scalings.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.354621
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  • 4
    Electronic Resource
    Electronic Resource
    A new method to determine the switching field distribution with application to barium ferrite powder (1991)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 69 (1991), S. 2465-2470 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: A method to determine the switching field distribution Hs((large-closed-square)cr〉gc0) of powder assemblies of magnetically hard materials with a random orientation of the easy axes is described. The method is based on the ferromagnetic resonance absorption and the measurements of remanence curves. Direct information about the switching field distribution is obtained from major and minor loops of the hysteresis of the microwave absorption loss. By fitting calculated remanence curves and measured remanence curves the switching field distribution and its distribution at each orientation angle (large-closed-square)cr〉gc0 is obtained. The application of this method leads to switching field distributions for coprecipitated barium ferrite, which are strongly correlated to the predictions of the theory of coherent rotation. The distribution of Hs for this sample is made narrower by an etching process or by magnetic dilution. For barium ferrite prepared by the conventional oxid ceramic method with additional milling, a monotonic increase of the switching field with increasing orientation angle is found. This increase is much smoother than the Kondorsky function provides.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.348683
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  • 5
    Electronic Resource
    Electronic Resource
    Bragg spectroscopy of impurities during the JET preliminary tritium experiment : Proceedings of the 9th topical conference on high temperature plasma diagnostics (1992)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 63 (1992), S. 5023-5025 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: Two Bragg spectrometers shared a shielded beamline, and monitored all significant plasma impurities throughout the Joint European Torus (JET) preliminary tritium experiment. The JET Active Phase Double Crystal Monochromator and a Bragg rotor spectrometer together monitored K-shell lines of Be, C, O, and Cl, and L-shell lines from metals such as Ni and Zn, in the wavelength range 0.2–11 nm. Background radiation was recorded during and after discharges, to assess the signal-to-noise ratio, and to monitor any activation or tritium ingress. Bragg spectroscopy was shown to be suitable for all impurities in magnetically confined D–T plasmas, using a thin foil to isolate tritium, and a low f-number shielded beamline. Future improvements to the signal-to-noise ratio are discussed in the context of a next-step machine such as ITER.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1143480
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  • 6
    Electronic Resource
    Electronic Resource
    Double-crystal x-ray spectroscopy at JET (1991)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 62 (1991), S. 889-898 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: A double-crystal monochromator has been brought into operation at JET to measure absolute wavelengths and intensities of impurity spectral lines in the soft x-ray region from about 0.1 to 2.3 nm. It is capable of operating also during the deuterium-tritium (active) phase of JET because its detector is very effectively shielded against neutrons and hard x rays. The spectrometer has been swept over a wide wavelength range, around characteristic line groups as well as monochromatic line scans.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1142026
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  • 7
    Electronic Resource
    Electronic Resource
    Low voltage drop plasma switch for inverter and modulator applications (1993)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 64 (1993), S. 2312-2319 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: A low forward voltage drop plasma switch has been developed for high-efficiency inverter and modulator applications. The switch, called the HOLLOTRON, is based on a grid-controlled, thermionic hollow-cathode discharge. A low forward voltage drop (10–20 V) is achieved by operating the hollow-cathode discharge in a static gas pressure of xenon. The dense plasma generated in the Ba-oxide dispenser hollow cathode is spread over a relatively large control grid area by a diverging magnetic field superimposed on the discharge. Interruption of the discharge current at high current densities ((approximately-greater-than)4 A/cm2) over the grid area is achieved by biasing the control grid sufficiently negative with respect to the plasma. The HOLLOTRON switch has demonstrated voltage stand-off of up to 20 kV, switching times of ≤0.3 μs, and pulse repetition frequencies of 20 kHz at 50% duty.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1143927
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  • 8
    Electronic Resource
    Electronic Resource
    Local crystal lattice curvature measurements for bent-crystal spectrometers (1990)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 61 (1990), S. 121-123 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: The geometrical orientation and curvature radius of the lattice of cylindrically bent crystals in high-resolution x-ray spectrometers for plasma diagnostics are determined locally on the crystal surface by means of a double-crystal device in conjunction with precise transverse displacements of the x-ray beam and accurate angular recordings of the crystal. Surface areas of the crystal which have imperfect orientation and curvature quality and hence contribute to resolving power degradation are thus clearly identified.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1141886
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  • 9
    Electronic Resource
    Electronic Resource
    On the modification of the Kondorsky function (1991)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 70 (1991), S. 3184-3187 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The validity of Kondorsky's switching field distribution for pinning magnets with rectangular hysteresis loops is extended to cases where the hysteresis loops are influenced by reversible rotation of the magnetization vectors in the domains. Caused by this influence, the monotonic Kondorsky function changes to modified Kondorsky functions HP(cursive-theta0) with minimal switching fields for orientation angles cursive-theta0(approximately-greater-than)0° when HP(cursive-theta0 = 0°) reaches the anisotropy field strength Ha. It is shown that the modified Kondorsky function is a more suitable description of experimental results in the literature than the Kondorsky function itself.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.349301
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  • 10
    Electronic Resource
    Electronic Resource
    Butt-coupled InGaAs metal-semiconductor-metal waveguide photodetector formed by selective area regrowth (1990)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 56 (1990), S. 1518-1520 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We report the monolithic integration of an InGaAs metal-semiconductor-metal Schottky barrier photodetector with a butt-coupled InP/InGaAsP/InP waveguide, where the latter is formed by selective area regrowth using organometallic chemical vapor deposition. A fast pulse response (60–65 ps full width at half maximum, with no discernible tail) and a high quantum efficiency (∼80%) were observed for 1.3 μm guided light with the detector biased at 7 V. A thin InAlAs Schottky barrier enhancement layer limited the dark current to ∼28 nA at this bias.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.103161
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