Abstract
Optical absorption spectroscopy has been applied to measure the absolute population densities of the first excited levels of atomic hydrogen H*(n=2) and argon Ar*(4s) in an expanding cascaded arc plasma in hydrogen-argon mixture. It is demonstrated that the method allows us to determine both H*(n=2) and Ar*(4s) absolute density radial profiles for H/sub 2/ admixtures in Ar ranging from 0.7% to 10% with good accuracy. The measured H*(n=2) densities are in the 10/sup 14/-10/sup 16/ m/sup -3/ range, and Ar*(4s) densities are in the range of 10/sup 15/-10/sup 18/ m/sup -3/. It has been shown, that the density of hydrogen excited atoms H*(n=2) serves as an indicator of the presence of argon ions and hydrogen molecules in the expanding plasma. A kinetic model is used to understand evolution of H*(n=2) density in the expansion, and to estimate the total atomic hydrogen population density and hydrogen dissociation degree in sub- and supersonic regions of the plasma
Original language | English |
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Pages (from-to) | 4499-4510 |
Journal | Journal of Applied Physics |
Volume | 76 |
Issue number | 8 |
DOIs | |
Publication status | Published - 1994 |