Number density of the 5s states during the ionisation relaxation of shock heated krypton
Abstract
The number density n sub d of the first excited level of krypton is determined during the ionization relaxation through the time-resolved absorption spectroscopy of the Kr I line 1s5 - 2p9 at a wavelength of 811.3 nm. Using a 1-m grating monochromator and a pulsed continuous background, light source densities between 2 x 10 to the 15th/cu m and 2 x 10 to the 18th/cu m are measured. Simultaneously, the electron densities are measured with a 4-mm microwave interferometer, and the values range from 2 x 10 to the 18th/cu m to 4 x 10 to the 19th/cu m. A diaphragm shock tube with a cross section of 52 x 52 sq mm and a length of 6 m is used to investigate shocks having Mach numbers ranging from M equals 12 (p sub 1 equals 4 torr) to M equals 8 (p sub 1 equals 40 torr). The shock tube is evacuated with a diffusion pump. Gassing introduces an impurity level ranging from 7 ppm (p sub 1 equals 40 torr) to 70 ppm (p sub 1 equals 4 torr), the test gas being Kr 4.0. The experimental results are compared with model calculations in order to deduce effective cross section constants. The reaction kinetics is modeled through a modified two-step ladder-climbing model under the assumption of a Maxwellian distribution function of the electrons.
- Publication:
-
Shock Tubes and Waves
- Pub Date:
- 1982
- Bibcode:
- 1982stw..proc..510Z
- Keywords:
-
- Absorption Spectroscopy;
- Electron Density (Concentration);
- Gas Ionization;
- Krypton;
- Molecular Relaxation;
- Shock Heating;
- Data Reduction;
- Gas Dynamics;
- Mathematical Models;
- Maxwell-Boltzmann Density Function;
- Microwave Interferometers;
- Reaction Kinetics;
- Shock Tubes;
- Temporal Resolution;
- Atomic and Molecular Physics