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  • 1
    Electronic Resource
    Electronic Resource
    Emission properties of different cathodes at E≤105 V/cm (2001)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 89 (2001), S. 2379-2399 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We present results of the investigation of different types of cathodes operating in an electron diode powered by a high-voltage generator (300 kV, 250 ns, 84 Ω, ≤5 Hz). The cathodes which have the same emitting area of 100 cm2 are made of metal–ceramic, carbon fibers, carbon fabric, velvet, or corduroy. We also tested carbon fibers and carbon fabric cathodes coated by CsI. It was shown that for all types of cathodes the electron emission occurs from the plasma which is formed as a result of a flashover of separate emitting centers. The amount of the emitting centers and the time delay in the electron emission were found to depend strongly on the accelerating electric field growth rate. Experimental data concerning the uniformity of the light emission from the cathode surface and divergence of the generated electron beams are presented. Data related to the general parameters of the diode, namely its impedance, power, and energy are given as well. For all the cathodes investigated the observed diode impedance indicated the existence of a quasistationary cathode plasma boundary for electron current density ≤20 A/cm2. We present the dependencies of the average emitted electron current density and of the time delay in the electron emission on the number of generator shots. We also present data of the vacuum deterioration as a result of the tested cathodes operation. The obtained data are discussed within the framework of plasma formation as a result of cathode surface flashover. © 2001 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1337924
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  • 2
    Electronic Resource
    Electronic Resource
    Electron energy and potential distribution in a diode with a ferroelectric cathode (2000)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 87 (2000), S. 3270-3278 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We study the time and space resolved energy of charged particles emitted from the plasma formed on the surface of polarized and unpolarized ferroelectric cathodes under the application of driving pulses having either a positive or negative polarity. It is found that the energy of the emitted charged particles does not exceed the amplitude of the driving voltage and is independent of the initial polarization state of the ferroelectric. In addition, data concerning the energy of the electrons under the application of an accelerating pulse of 25 kV, and data concerning the electron beam uniformity and the time resolved potential distribution inside the anode–cathode gap of the electron diode are presented. We discuss our experimental results within the framework of the incomplete surface discharge model. © 2000 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.372335
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  • 3
    Electronic Resource
    Electronic Resource
    High-current electron beam generation by a pulsed hollow cathode (2002)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 91 (2002), S. 3431-3443 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: In this paper the parameters of a hollow-cathode electron source and the generated electron beam are presented. A gas puff valve is used to provide a sharp pressure gradient between the cathode cavity and the accelerating gap. To produce the plasma inside the hollow cathode we used a pulse forming network (10 kV, 5–10 μs, 5 Ω). Generation of a high-current electron beam was achieved under an accelerating voltage of 20-kV amplitude and 500-ns pulse duration. The parameters of the He gas and the plasma inside the cathode and the accelerating gap were studied by electrical and optical diagnostics for different gas pressures and discharge current amplitudes. It was found that the operation of the hollow cathode is characterized by a negative anode potential fall and that the plasma density and temperature inside the hollow cathode do not exceed 5×1012 cm−3 and 14 eV, respectively. The parameters of the electron beam were studied for different discharge current amplitudes and anode grid cell sizes. It was shown that efficient electron beam generation with a beam current amplitude of up to 300 A is achieved without significant increase of the plasma potential. Space-charge neutralization processes in the accelerating gap explain the excess of the electron current density above its space-charge-limited value, in agreement with the measured potential distribution in the accelerating gap. The results of computer simulations of the hollow-cathode operation are in satisfactory agreement with the obtained experimental data. © 2002 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1448895
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  • 4
    Electronic Resource
    Electronic Resource
    Excitons in monoclinic zinc diphosphide. Longitudinal exciton and the mixed mode (1999)
    Springer
    Physics of the solid state 41 (1999), S. 170-178 
    Details
    ISSN: 1063-7834
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract Exciton absorption spectra in high-quality β-ZnP2 single crystals have been investigated at T=1.7 K for various directions of the wave vector and various polarization states of the radiation. It has been unambiguously established that the additional high-energy A series, which in some works has been called a D series and ascribed to ZnP2 crystals, of so-called “rhombic” symmetry,1,8,10,11 is an intrinsic exciton of the β-ZnP2 series. A mixed mode has been detected for the first time, and the energy of the longitudinal exciton has been determined. The selection rules for the exciton transitions have been analyzed by a group-theoretical approach, and the symmetry of the nS states of the single exciton has been established on the basis of the experimental data — Γ 2 − (z).
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1134/1.1130750
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  • 5
    Electronic Resource
    Electronic Resource
    Excitons in monoclinic zinc diphosphide: Orthoexciton and polariton effects at n=1 resonance (2000)
    Springer
    Physics of the solid state 42 (2000), S. 1625-1633 
    Details
    ISSN: 1063-7834
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract Quantitative investigations of the hydrogen-like exciton B series in the absorption spectra of the β-ZnP2 crystal for various wave vector directions and polarization states of radiation are conducted. It is shown that the B spectrum constitutes a single orthoexciton series with S-type envelope functions, and low-energy components in doublet lines belong to the S-type for lines in the series with n≥3. Polariton effects are clearly manifested at the B n=1 exciton resonance, and Bouguer’s law is violated. The oscillator strength tensor components are determined for transitions to the exciton states of the B series, and the polariton parameters at the B n=1 exciton resonance are calculated.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1134/1.1309441
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