Recombination, Ionization, and Nonequilibrium Electrical Conductivity in Seeded Plasmas

Citation

Cool, Terrill Alan (1965) Recombination, Ionization, and Nonequilibrium Electrical Conductivity in Seeded Plasmas. Dissertation (Ph.D.), California Institute of Technology. doi:10.7907/JB0S-4521. https://resolver.caltech.edu/CaltechETD:etd-09122002-115831

Abstract

NOTE: Text or symbols not renderable in plain ASCII are indicated by [...]. Abstract is included in .pdf document. This study is concerned with the theoretical and experimental description of the behavior of dense seeded plasmas under the influence of applied electric fields under steady-state conditions as well as during electronic ionizational and recombinational relaxations. Extensive experimental measurements of nonequilibrium electrical conductivities, electron temperatures, recombination rates, and ionization rates have been performed in dense potassium-seeded plasmas. Measurements have been made under conditions of practical importance for proposed MHD energy converters in argon-potassium and helium-potassium plasmas. Translational gas temperatures ranged from 1250 to 2000 [degrees]K; seed concentrations were varied between .1 and 1 mole percent; and the total gas pressure was 1 atmosphere. Extensive steady-state measurements of nonequilibrium electrical conductivity, and the influence upon it of variations in gas temperatures, seed concentrations, atomic cross sections, current densities, electric field strengths, and energy loss processes have been made. This detailed experimental work has led to important modifications of existing theory which have enabled an accurate description of the plasma in terms of a simple physical model. Electron temperature measurements provide a conclusive and quantitative verification of the validity of this physical model. The essential theoretical modifications made here are the inclusion of both inelastic and elastic electronic collisional energy loss mechanisms in a manner which accurately reflects the essential physical differences between these two processes in terms of fundamental atomic properties, and employs no adjustable parameters. Additionally, consideration of the detailed energy dependence of the atomic cross sections and the inclusion of both electron-ion and electron-atom interactions has been essential in accurately describing the experimental results. Experimental measurements of recombination rates, ionization rates, and electronic collisional relaxation characteristics of potassium seeded plasmas have been performed. Measured recombination and ionization rates for potassium show good agreement with theoretical calculations based upon a formulation employing the Gryzinski classical inelastic collision cross sections and a simple physical model of the relaxing plasma

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