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Accession Number:
AD0670838
Title:
STUDY OF THE INITIAL IONIZATION PROCESS IN A STRONG SHOCK WAVE,
Corporate Author:
TORONTO UNIV (ONTARIO) INST FOR AEROSPACE STUDIES
Report Date:
1968-06-01
Abstract:
A theoretical and experimental investigation was made of the initial ionization processes in a strong shock wave in hydrogen. The relaxation length for ionization, which is principally determined by the rate of excitation, was measured and from a comparison with the theory an estimate was obtained for the cross-section for atom-atom excitation collisions. Detailed theoretical calculations showed that the electron temperature approaches to within a few percent of the atom temperature in a distance that is small compared to the total relaxation length for ionization. This enabled considerable simplification for it indicated that a single temperature model could be used in calculating the theoretical relaxation profile over the experimental range of operating conditions. An electromagnetic shock-tube, with a Philippov pinch to create the driver plasma, was employed to produce shock waves of the required velocity. The ionization behind the shock front was studied by means of a double frequency Mach-Zehnder interferometer, with a ruby laser and a KDP crystal a second harmonic generating crystal as the light source. A close agreement between the theoretical and experimental electron density profiles, behind the shock front, was obtained for small relaxation lengths, when the cross-section for the atom-atom excitation collisions was assumed to be about .021 times that of the corresponding electron-atom excitation collision. For larger relaxation distances which correspond to shock speeds less than 3,300,000 cmsec it was necessary to introduce corrections for blast wave effects in order to get good agreement with experiment for the same value of cross-section. Author
Pages:
0090
Contract Number:
AF-AFOSR-366-66
File Size:
0.00MB
