Influence Of Electron-atom Cross Section Uncertainties On Shock Wave Structure


The exact value of the electron-atom collisional ionization cross section for argon is not accurately known. The purpose of the present research is to determine numerically the effect of varying the magnitude of the electron-atom cross section on nonequilibrium shock-wave structure. Mach 18 shock waves propagating into an argon-like gas at 1 cm-Hg and 300°K have been analyzed. Thermal, ionizational, and excitational non-equilibrium are considered in the relaxation region behind the shock wave. Electrons in the relaxation region are formed by a two-step collisional process, wherein the atom is first excited and then it is ionized. The precursor is formed by ground and excited state continuum radiation and line radiation which is emitted, but not reabsorbed, in the region behind the shock wave. When the electron-atom ionization cross section is varied from 1·86 x 10-4 to 1·86 x 10-2 cm2/erg, the results show that (1) it influences the coupling between the precursor and relaxation region through the radiative source functions, (2) it does not influence the distance necessary to attain equilibrium behind the shock wave, (3) it inversely influences the magnitude of the precursor ionization, and excitation, and (4) it inversely influences both the free electron and excited state population in the relaxation layer. © 1974.


Mechanical and Aerospace Engineering

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Article - Journal

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Publication Date

01 Jan 1974