Spectroscopic Measurement of Electron Concentration in Shock-Heated Gas

Results of spectroscopic measurements of the equilibrium electron concentration behind a strong shock wave in argon at a shock-wave velocity of 4.2 km/s and a pressure ahead of the wave front of 5 Torr and in O₂, N₂, and air in the velocity range from 8.3 to 11.3 km/s at an initial pressure of 0.25 Torr are presented. The measurement method was based on an analysis of broadening of the hydrogen-atom H_β line of the Balmer series in the spectrum of the integral radiation density of the studied gas to which a small amount of H₂ was added (~1%). The dependence of the electron concentration on the shock-wave velocity in O₂, N₂, and air was established. The results were compared with available experimental and calculated data.