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  • 1
    Electronic Resource
    Electronic Resource
    A numerical solution of the Boltzmann equation for high-powered short pulse microwave breakdown in nitrogen (1989)
    New York, NY : American Institute of Physics (AIP)
    Physics of Fluids 1 (1989), S. 2507-2515 
    Details
    ISSN: 1089-7666
    Source: AIP Digital Archive
    Topics: Physics
    Notes: A theoretical formulation that provides a basis for generating approximate solutions of the Boltzmann equation for the study of high-powered microwave pulses interacting with a background atmosphere is given. A numerical scheme is implemented using realistic cross sections for electron–nitrogen collisions, including excitation and ionization. It is found that the numerical results agree well with previous experimental and theoretical values when α is less than about 0.1 kV/cm Torr, where α is the effective electric field divided by the pressure (α=Ee/P). Results are presented providing a simple fit for the time averaged momentum transfer rate and the ionization rate as a function of the microwave electric field E, wavelength λ, and gas pressure P, for 0.1≤α≤1.0 kV/cm Torr. This fit is compared with recent experimental data for breakdown times.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.859186
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  • 2
    Electronic Resource
    Electronic Resource
    Magnetic field compression and evolution in laser-produced plasma expansions (1986)
    [S.l.] : American Institute of Physics (AIP)
    Physics of Fluids 29 (1986), S. 2007-2012 
    Details
    ISSN: 1089-7666
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The evolution of a magnetic bubble resulting from the expansion of Nd-laser-generated plasma into a photoionized magnetized background plasma is examined experimentally and is compared with theory and computer simulations. The initial laser-produced plasma speed is greater than the plasma sound and Alfvén speeds and is energetic enough to be unmagnetized; the background plasma is effectively magnetized and its density is varied from the collisionless to the collisional regimes. The data support theoretical predictions that the initial expansion of the magnetic bubble is dominated by the uncoupled laser-produced plasma.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.865578
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  • 3
    Electronic Resource
    Electronic Resource
    Spectroscopic and interferometric measurements of laser–plasma produced blast waves (1986)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 57 (1986), S. 2058-2058 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: A laser-produced plasma generates blast waves as it expands supersonically into a stationary photoionized background gas (N2) at a pressure of 1–5 Torr.1 Using a combination of spectroscopic and interferometric measurements, time- and space-resolved values of the temperature and density are obtained. This study was performed on targets in the NRL Pharos III laser facility with laser energies of 20–120 J and pulse durations of ∼5 ns. A 1-m spectrograph equipped with three photomultiplier channels, which are calibrated on an absolute scale, is used for the spectroscopic measurements. The interferometry is done with a folded-wavefront interferometer. It uses an optical probe pulse at 5270 A(ring) that is split off of the main laser pulse, reduced in pulse duration (∼300 ps), and time delayed. Interferometric measurements can be made simultaneously with the spectroscopic measurements. Experimental data and the technique of analysis will be shown. This work was supported by the Defense Nuclear Agency.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1138735
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  • 4
    Electronic Resource
    Electronic Resource
    Energy deposition in N and N+ by high-energy electron beams (1988)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 64 (1988), S. 982-993 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: A discrete, time-dependent energy deposition model is used to study high-energy electron-beam (100 eV–10 MeV) deposition in N and N+. Both time-dependent and steady-state secondary electron distributions are computed. The loss function, mean energies per electron-ion pair production (W), production efficiencies, and distribution functions are presented for a wide range of energies. The latest experimental and theoretical cross sections are used in the model which predicts that W is approximately 31 eV for N and 72 eV for N+ over a wide range of beam energies. The sensitivity of these results to assumed background ionization fractions is also investigated.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.341806
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  • 5
    Electronic Resource
    Electronic Resource
    Collisional-radiative ionization and recombination model for high-temperature air and its application to discharges (1988)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 64 (1988), S. 89-97 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: A collisional-radiative (C-R) model for high-temperature air is developed. Ionization and recombination coefficients are presented for electron temperatures between 1.0 and 3.0 eV and electron densities between 1016 and 1019 cm−3. For an assumed airlike mixture of 80% nitrogen and 20% oxygen, these results are compared with C-R coefficients of nitrogen and oxygen plasmas developed separately and show little difference. The inclusion of charge-exchange effects does not alter the coefficients. Saha decrements for air are used to delineate the onset of local thermodynamic equilibrium (LTE) for the above conditions. These thresholds are compared to other criteria and show some difference. Finally, ratios of spectral line intensities are presented in terms of the Saha decrements as a means of diagnosing high-temperature air discharges, such as lightning channels, without requiring LTE.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.341224
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  • 6
    Electronic Resource
    Electronic Resource
    Electron energy deposition in atomic oxygen (1988)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 63 (1988), S. 1-10 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: A discrete, time-dependent energy deposition model is developed and applied to the study of high-energy electron-beam (100 eV–10 MeV) deposition in atomic oxygen. Secondary electron distributions are computed and observed to relax to steady-state results. Characteristic relaxation times are shown. The loss function, mean energies per electron-ion pair production, production efficiencies, and distribution functions are presented for a wide range of energies. The model uses the latest experimental and theoretical cross sections as input.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.340491
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  • 7
    Electronic Resource
    Electronic Resource
    High-energy electron beam deposition and plasma velocity distribution in partially ionized N2 (1990)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 67 (1990), S. 679-690 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The electron distribution function is calculated for a plasma created when a high-current, high-energy (∼MeV) electron beam enters nitrogen gas. No spatial dependence is considered for the distribution function and the velocity is expanded in the two-term approximation. Time dependence is retained. Benchmark calculations are presented that compare code output with experimental results of electron deposition studies and swarm studies in nitrogen. Production efficiencies are given. The effect of inner-shell processes is discussed. An example illustrates the importance of the beam-induced electric field on the plasma generation and behavior. It shows that considerable ohmic energy deposition can be involved and that, consequently, production of certain species can be greatly enhanced.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.345772
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  • 8
    Electronic Resource
    Electronic Resource
    Energy deposition in O+ by high-energy electron beams (1989)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 66 (1989), S. 5216-5227 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: A discrete, time-dependent energy-deposition model is used to study high-energy electron-beam (100 eV–10 MeV) deposition in O+. Both time-dependent and steady-state secondary electron distributions are computed. The distribution functions, production efficiencies, loss function, and mean energies per electron-ion pair (W) are presented for a wide range of energies. The model predicts W to be approximately 72 eV for O+ over a wide range of beam energies when inner-shell ionization is neglected. The results change when inner-shell ionization, followed by the accompanying emission of an Auger electron, is included. The model also includes inner-shell excitation to high Rydberg states. Changes resulting from these processes are noted and discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.343707
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  • 9
    Electronic Resource
    Electronic Resource
    Mobilization and fractionation of137Cs in calcareous soils (1989)
    Springer
    Journal of radioanalytical and nuclear chemistry 130 (1989), S. 195-201 
    Details
    ISSN: 1588-2780
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Energy, Environment Protection, Nuclear Power Engineering
    Notes: Abstract Mobility of137Cs was investigated in columns of calcareous loam and clay soils leached under river water, NH4OAc, KCl, CaCl2, and EDTA. Fractionation of Cs into ten sequential fractions was accomplished in the leached soils as well as in soil samples received carrier-free137Cs and incubated for 60 d. At the end of 90 d of leaching with river water and CaCl2, the bulk of Cs applied (〉97%) was found to remain in the upper 1 cm of soil columns. On the other hand, the reduction in Cs concentration was approximately 30% with NH4OAc, 18% with KCl, and 10 to 25% with EDTA. The major soil constituents appeared to be responsible for retaining Cs were clay, silt, and Fe oxides. The leaching consistently increased the magnitude of fractions bound to clay minerals and in most cases decreased the fractions of water soluble, exchangeable, carbonate, and organic matter.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02037713
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  • 10
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    Theory of Resonance Broadening of Spectral Lines by Atom-Atom Impacts (1965)
    American Physical Society
    Details
    Publication Date: 1965-11-15
    Print ISSN: 0031-899X
    Electronic ISSN: 1536-6065
    Topics: Physics
    Published by American Physical Society
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