STUDY OF THE INITIAL IONIZATION PROCESS IN A STRONG SHOCK WAVE,
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)
Document Details
- Document Type
- Technical Report
- Publication Date
- Jun 01, 1968
- Accession Number
- AD0670838
Entities
People
- A. N. Belozerov
Organizations
- University of Toronto