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  • 1
    Digitale Medien
    Digitale Medien
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 69 (1998), S. 2160-2165 
    ISSN: 1089-7623
    Quelle: AIP Digital Archive
    Thema: Physik , Elektrotechnik, Elektronik, Nachrichtentechnik
    Notizen: To satisfy the electrical and thermomechanical requirements for a continuous wave millimeter wave beam transmission, a window assembly using a large size synthesized diamond disk has been developed. Such window systems are needed as a vacuum barrier and tritium shielding in future electron cyclotron heating systems for fusion plasma heating and noninductive electron cyclotron current drive. The diamond used in this study was manufactured by chemical vapor deposition (CVD) and consists of a polycrystalline diamond disk 96 mm in diameter and 2.23 mm thick. The disk was built into an assembly in which two Inconel tubes were bonded on both sides of the plate to provide vacuum shielding and water cooling to the edge of the disk, leaving an effective window aperture of 83 mm. It will be shown that, as a result of the high thermal conductivity and low dielectric loss exhibited by this grade of CVD diamond, the temperature increase of the window due to the absorption of high-power millimeter wave radiation could be minimized by simple water edge cooling at room temperature. During transmission of a focused Gaussian beam of 170 GHz, 110 kW, 10 s, the temperature increase at the center of the window reached a steady state condition at a value of approximately 40 K, in good agreement with calculated values. Water-edge-cooled CVD diamond windows promise to provide a practical technical solution for the transmission of continuous millimeter wave transmission in excess of 1 MW. © 1998 American Institute of Physics.
    Materialart: Digitale Medien
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  • 2
    Digitale Medien
    Digitale Medien
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 80 (1996), S. 3338-3345 
    ISSN: 1089-7550
    Quelle: AIP Digital Archive
    Thema: Physik
    Notizen: CuAlxGa1−xSe2 alloy layers were successfully grown on GaAs(001) by low-pressure metalorganic vapor phase epitaxy. The distribution coefficient of Al was unity. All alloy layers had their c-axis normal to the substrate plane. Exciton resonance energies were determined as a function of x by means of photoreflectance measurements. A quadratic dependence of exciton energies on x was confirmed. The spin-orbit splittings of the epilayers were approximately the same as that of bulk crystals. The magnitudes of crystal-field splittings were larger than that of bulk crystals, and this was explained in terms of residual tensile biaxial strain in the epilayers. The color of the low-temperature photoluminescence (PL) changed from red to crimson, orange, yellow, green, and bluish-purple with increasing x. A peak due to a free-to-acceptor transition was dominant in the PL spectra of the alloy layers. The acceptor ionization energy increased with increasing x, and the result may reflect an increase of the hole effective mass. © 1996 American Institute of Physics.
    Materialart: Digitale Medien
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  • 3
    Digitale Medien
    Digitale Medien
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 80 (1996), S. 1106-1111 
    ISSN: 1089-7550
    Quelle: AIP Digital Archive
    Thema: Physik
    Notizen: Optical absorption spectra of CuInSe2 single crystals were measured for the samples with −0.150≤x≤0.053, where x represents a degree of nonstoichiometry in the formula Cu1−xIn1+xSe2. The Urbach's tail was observed for all samples between 90 K and room temperature. The Urbach's energy, which represents an arbitrary intensity of exciton–phonon interaction, was almost constant for the Cu-rich samples (x〈0), while it increased with increasing In composition for the In-rich ones (x(approximately-greater-than)0). Such an increase of the Urbach's energy was explained to be due to enhanced electronic distortion caused by the compositional deviation from stoichiometry in terms of simultaneous influence of electron–phonon interaction and structural disorder. © 1996 American Institute of Physics.
    Materialart: Digitale Medien
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  • 4
    Digitale Medien
    Digitale Medien
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 64 (1988), S. 3492-3496 
    ISSN: 1089-7550
    Quelle: AIP Digital Archive
    Thema: Physik
    Notizen: A new type of graphoepitaxial growth of zinc sulfide (ZnS) crystalline thin films has been investigated. The substrate is polyimide coated with various thin films. It has an inverted pyramidal replica pattern taken from textured (100) single-crystalline silicon. Crystallinity and growth orientation of films were examined by scanning electron microscopy and x-ray pole figures. It has been confirmed that the crystal was grown from the bottom of the inverted pyramids. The results show that the graphoepitaxial effects are strongly sensitive to the ability of the semiconductor to wet the substrate coating materials at the nucleation temperature. The controllability of the crystallographic orientation normal to the substrate by the synthetic pattern is more than 85% in the present technology status.
    Materialart: Digitale Medien
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  • 5
    ISSN: 1471-4159
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Medizin
    Notizen: —Acetylcholine, 5-hydroxytryptamine, and norepinephrine concentrations were measured in the telencephalon, diencephalon plus mesencephalon (midbrain), and pons-medulla oblongata of rats exhibiting behavioral excitation while working on a Sidman avoidance schedule and injected with 50 mg/kg iproniazid 16 hr before being given 2 mg/kg tetrabenazine. Acetylcholine concentrations in all three brain areas decreased and returned to normal levels at different times. The time course of increased response rates correlated best with the acetylcholine levels in the telencephalon. Both the 5-hydroxytryptamine and norepinephrine concentrations remained similar to the iproniazid control values during the period of behavioural excitation. However, the norepinephrine concentration in the midbrain showed a continuous decreasing trend toward naive control levels. These data suggest that changes in a cholinergic system in the telencephalon and a noradrenergic system in the midbrain operate in the maintenance of behavioural excitation.
    Materialart: Digitale Medien
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  • 6
    Digitale Medien
    Digitale Medien
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 56 (1985), S. 764-765 
    ISSN: 1089-7623
    Quelle: AIP Digital Archive
    Thema: Physik , Elektrotechnik, Elektronik, Nachrichtentechnik
    Notizen: A demountable vacuum window of fused quartz was designed and successfully used for a high-power circular waveguide system combined with 28-GHz gyrotrons for electron cyclotron resonance heating experiments in the GAMMA 10 tandem mirror. The power reflection coefficient is very low (≤0.1%) and it works satisfactorily at the transmitted power level of 120 kW with 60-ms pulse width. No problems are expected up to 200-kW transmission with 0.1-s duration.
    Materialart: Digitale Medien
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  • 7
    Digitale Medien
    Digitale Medien
    Palo Alto, Calif. : Annual Reviews
    Annual Review of Sociology 16 (1990), S. 263-299 
    ISSN: 0360-0572
    Quelle: Annual Reviews Electronic Back Volume Collection 1932-2001ff
    Thema: Sociologie
    Materialart: Digitale Medien
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  • 8
    Digitale Medien
    Digitale Medien
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 66 (1989), S. 4770-4774 
    ISSN: 1089-7550
    Quelle: AIP Digital Archive
    Thema: Physik
    Notizen: A systematic experimental approach has been performed to achieve orientation-controlled nucleation and graphoepitaxial growth of germanium on the replica substrate with a textured single-crystalline silicon (001) surface. The recrystallization of germanium was successfully obtained by scanning a cw argon-ion laser on a germanium/metal eutectic alloy system. It was found that the crystallographic orientation of germanium is strongly dependent on the recrystallization conditions such as laser power, scan direction of laser beam, size of surface relief, and wetting condition to crystallized material. The 〈001〉 directions of the recrystallized germanium are normal to the substrate, and the 〈110〉 directions are parallel to the valleys among the pyramidal relief, i.e., the crystallographic orientation coincides with one of original silicon (001) single crystal. It has been confirmed that the crystallite sizes range from 2 to 10 μm, and the deviation of the [001] crystallographic orientation distribution is less than 7°. A possible growth mechanism of graphoepitaxy is also discussed.
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  • 9
    ISSN: 1089-7666
    Quelle: AIP Digital Archive
    Thema: Physik
    Notizen: Strong one-pass absorption of high-power microwaves is observed at the fundamental electron cyclotron resonance in an axisymmetric end mirror of the GAMMA 10 tandem mirror [Phys. Rev. Lett. 55, 939 (1985); Phys. Fluids 29, 2781 (1986)]. The radial profile of microwave power deposition is directly measured without the influence of wall reflection. It coincides with that of the axial flow of warm electrons driven by the fundamental heating as well as with that of the plasma potential at the resonance. This indicates that strong electron cyclotron heating largely affects the potential formation through driving an axial flow of warm electrons.
    Materialart: Digitale Medien
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  • 10
    ISSN: 1089-7666
    Quelle: AIP Digital Archive
    Thema: Physik
    Notizen: Hot electrons have been produced by second harmonic electron-cyclotron resonance heating in axisymmetric end mirrors of the tandem mirror GAMMA10 [Phys. Rev. Lett. 55, 939 (1985)] with an on-axis density fraction reaching 80% and temperature of 25–50 keV, satisfying theoretically required conditions for the formation of thermal barriers. The successful control of the electron temperature may be attributed to the relativistic detuning of the second harmonic resonance for localized microwave power absorption. The time evolutions of relevant parameters are studied with extensive diagnostics.
    Materialart: Digitale Medien
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