Determination of the Gas Temperature in the Afterglow of Pulsed Discharges by Microwave Probing of Standing Acoustic Waves

Abstract

The time-varying gas temperature of afterglow plasmas is determined from the frequencies of standing acoustic waves which are produced during the breakdown of low-pressure gases (0.1–20 Torr). The sound field is probed with free-space microwave (9 and 70 Gc/sec) interferometers in transmission and reflection. Capacitor discharges are found to heat the gas significantly. The temperature does not decay to room temperature within the observed afterglow periods.