Accession Number : AD0670838

Title :   STUDY OF THE INITIAL IONIZATION PROCESS IN A STRONG SHOCK WAVE,

Corporate Author : TORONTO UNIV (ONTARIO) INST FOR AEROSPACE STUDIES

Personal Author(s) : Belozerov,A. N.

Report Date : JUN 1968

Pagination or Media Count : 90

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 cm/sec 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)

Descriptors :   (*GAS IONIZATION, *SHOCK WAVES), HYDROGEN, RELAXATION TIME, EXCITATION, INTERACTIONS, TEMPERATURE, SHOCK TUBES, INTERFEROMETERS, ELECTRON DENSITY, PROBABILITY, CANADA

Subject Categories : Plasma Physics and Magnetohydrodynamics

Distribution Statement : APPROVED FOR PUBLIC RELEASE