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  • 1
    Electronic Resource
    Electronic Resource
    Transport and interaction of a relativistic electron beam in low pressure neutral gases (1989)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 66 (1989), S. 1901-1907 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: A numerical study of the transport of a 0.27-MeV, 6.6-kA, 40-ns relativistic electron beam in argon and hydrogen in the pressure range of 0.01–1.0 Torr taking into account charge and current neutralization effects is presented. Ionization by avalanching and by beam and plasma electrons is included in the calculation of plasma density buildup. Plasma heating resulting from return current heating and two-stream instability is taken into account. The computed results of charge transport, net current, and breakdown time are compared with experimental results obtained in this laboratory. The results are in reasonable agreement with the experiment and show a maximum charge transport of 75% at the optimum pressure of 0.1 and 0.6 Torr in argon and hydrogen, respectively. The calculations indicate beam-generated plasma parameters of 1019–1020 m−3 density and 1–5 eV electron temperature.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.344322
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  • 2
    Electronic Resource
    Electronic Resource
    Current multiplication during relativistic electron-beam propagation in a subTorr-pressure gas (1988)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 64 (1988), S. 6626-6630 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The current multiplication observed when a relativistic electron beam is propagated in an initially neutral gas at subTorr pressures (0.1–0.3 Torr) is generally attributed to the two-stream instability. A general expression for this current gain is derived for a scattered beam propagating in a neutral gas, which takes into account a quasihydrodynamic expression for the beam energy loss. Moreover, the beam-to-plasma density ratio is obtained as a function of time for a given beam pulse by numerically solving the electron energy and continuity equations. It is found that at a given beam-to-plasma density ratio, the current gain increases with increasing the beam energy, with the increase being most rapid for the small scattering angles. A finite average scattering angle is seen to reduce the current multiplication. The experimentally observed peak current gains are in good agreement with the predicted peak gains obtained by taking into account the time-evolved beam-to-plasma density ratio.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.342044
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  • 3
    Electronic Resource
    Electronic Resource
    Spatial and temporal distributions in exploding-wire plasmas (1988)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 63 (1988), S. 2576-2582 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The effect of small energy pulses (τ∼0.1–10 ns) in exploding-wire plasmas has been analytically investigated in this study. It is shown that the deposited energy distribution is an increasing function of the radial distance in wire. The energy distribution is more pronounced with smaller τ and becomes uniform for τ〉10 ns for given wire radius ∼12.5 μm. The resulting fragments exhibit a distribution in sizes and are smaller towards the wire surface due to a higher energy density (E) than around the axis. For E∼Ee (the energy density needed for total evaporation), the fragment sizes range from μm to nm from axis towards surface, respectively. Subsequent to explosion, for E≥Ee, there are distributions in plasma temperature (Tp) and plasma density (Np) as well. Typically for E∼10 kJ/g in copper, Tp is more than a few percent higher at the leading end than in the trailing end. As compared to this, E(very-much-greater-than)Ee gives a uniform plasma with uniform Tp irrespective of τ. Consequently, uniform plasma can be obtained either with very large E, or in case of small E with large τ.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.340993
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  • 4
    Electronic Resource
    Electronic Resource
    Effective scattering angle of relativistic electron beams injected through an anode foil (1988)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 64 (1988), S. 1781-1784 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The values of the effective scattering angle 〈θ〉 of a relativistic electron beam injected through an anode foil are analyzed by different methods in the light of reported values for various beam-plasma heating experiments. Wide variations in calculated 〈θ〉 are noted depending on the method used. It is argued that the 〈θ2〉1/2 expression corrected for Molière screening and the (1/e) equivalent from the Monte Carlo code give nearly the same average scattering angle and one of them should be used to determine 〈θ〉. It is also seen that a small variation in 〈θ〉 alters significantly the plasma temperature estimate.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.341775
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  • 5
    Electronic Resource
    Electronic Resource
    Relativistic electron beam heating of a hydrogen plasma in open confinement systems: Theoretical model (1988)
    [S.l.] : American Institute of Physics (AIP)
    Physics of Fluids 31 (1988), S. 606-611 
    Details
    ISSN: 1089-7666
    Source: AIP Digital Archive
    Topics: Physics
    Notes: A one-dimensional theoretical model for predicting the heating of a hydrogen plasma in open confinement systems by a relativistic electron beam is presented. Direct energy transfer of beam electrons via interaction with large amplitude waves of the two-stream instability and Ohmic dissipation of plasma return current caused by classical and anomalous resistivities are considered as power input terms. For loss terms, various atomic processes and heat conduction mechanisms are considered. In the light of observed changes in the average scattering angle of the beam inside the plasma, criteria deciding the character of beam–plasma interaction and the estimation of direct power transfer are discussed. The numerical results are presented with a reference to the results of the beam–plasma heating experiments reported in the literature. Better agreement is observed between the experiment and the present analysis.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.866843
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  • 6
    Electronic Resource
    Electronic Resource
    Effect of rise time and pulse width on the transport and interaction of a 1 MeV, 15 kA relativistic electron beam in low pressure argon and hydrogen (1989)
    New York, NY : American Institute of Physics (AIP)
    Physics of Fluids 1 (1989), S. 1860-1865 
    Details
    ISSN: 1089-7666
    Source: AIP Digital Archive
    Topics: Physics
    Notes: A numerical study of the effect of rise time (10–30 nsec) and pulse width (30–100 nsec) on the transport and interaction of a 1 MeV, 15 kA relativistic electron beam (REB) in argon and hydrogen in the pressure range 0.05–1.0 Torr is reported. The computations have been carried out taking into account charge and current neutralization effects, plasma heating by return current, and two-stream instabilities. The results of the study show that charge transport increases for short rise times and longer pulse widths at the optimum pressure in the range 0.1–0.2 Torr. With a rise time of 30 nsec and a pulse width of 100 nsec, the 1 MeV, 15 kA REB generates a plasma with density 1–10×1021 m−3, an electron temperature of 4–20 eV, and transports with 90% efficiency at the optimum pressure.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.858918
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  • 7
    Electronic Resource
    Electronic Resource
    Induction-coupled ion-beam source : International conference on ion sources (1990)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 61 (1990), S. 490-492 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: A prototype rf ion source for extracting a hydrogen-ion beam has been developed. The system consists of a rf source and a water-cooled quartz tube, which contains the plasma. The rf power is coupled through a four-turn coil located outside the tube. A perforated metal grid and an aperture located about 8 mm from the grid has an opening of 5 mm in diameter. The axially extracted beam is transported through a column of about 1 m maintained at a pressure of 10−4 Torr, while the pressure in the plasma region is about 10−2 Torr. The rf source is a class-C, variable-power oscillator of fixed frequency 7 MHz. Operating the system with about 300 W in the discharged plasma, a continuous proton beam of 55 μA has been observed at a distance of 10 cm from the extracter at a voltage of 2.5 kV. Under similar operating conditions an argon-ion beam of 14 μA has been extracted. Experiments are in progress to optimize the extraction of ions at 10 kV, increase the rf power, and provide a suitable focusing system to transport the beam at a distance of 1 m with maximum efficiency.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1141953
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  • 8
    Electronic Resource
    Electronic Resource
    Thermionic emission characteristics of LC20M electrode material in open cycle MHD systems (1980)
    Springer
    Applied physics 22 (1980), S. 283-285 
    Details
    ISSN: 1432-0630
    Keywords: 79.40
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Abstract The work function was measured in a vacuum of 10−5 Torr for magnesia incorporated lanthanum chromite based ceramic designated LC2OM. The results obtained are φ R =2.75eV andA R =0.11 A/cm2 K2 which ensure that LC2OM has favourable electron emission characteristics for MHD hot electrode material. The measurements have been carried out in the temperature range from ambient to 1700 K.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00899878
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  • 9
    Electronic Resource
    Electronic Resource
    Effect of process parameters on the properties of plasma-sprayed superconducting Y1Ba2Cu3O7−x coatings (1989)
    Springer
    Applied physics 48 (1989), S. 489-492 
    Details
    ISSN: 1432-0630
    Keywords: 74 ; 52.75.-d ; 81.20-n
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Abstract A study on the effect of powder, spray and coating parameters on superconducting properties of plasma-sprayed Y1Ba2Cu3O7−x coatings has been carried out. Optimised spray parameters to yield strong, adherent and dense coatings on many substrates including AISI 304 SS and alumina have been obtained. Coatings show superconductivity after oxygen annealing at 950°C for an hour. Coatings thinner than 100 μm do not show zero resistivity down to 77 K due to weak links between granular superconductors. Coatings prepared with fine powder have superior superconducting properties, viz. higherT c andJ c values than coarse powder coatings. The choice of substrate material strongly affects theJ c values.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00619723
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  • 10
    Electronic Resource
    Electronic Resource
    Infrared spectra of the ceramic YCrO3 doped with strontium (1988)
    Springer
    Journal of materials science 7 (1988), S. 413-414 
    Details
    ISSN: 1573-4811
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01730761
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