Dynamics of the gas discharge in noble gases sustained by the powerful radiation of 0.67 THz gyrotron

This work was carried out in a frame of the study of the discharge propagation in noble gases in focused beams of the terahertz frequency range radiation. A 40 kW at 670 GHz pulsed gyrotron was used as a source of heating radiation. The propagation velocity of the discharge front in various noble gases (argon, krypton, and a helium–argon mixture) was measured over a wide pressure range (from several atmospheres to several Torr, depending on the type of gas). It is shown that the discharge propagation velocity decreases with increasing gas pressure. Moreover, the velocity decreases with an increase in the atomic mass of the gas from several units of 107 cm/s in the case of a helium–argon mixture to 106–105 cm/s (depending on pressure) in the case of krypton over the entire pressure range. Measurements of the discharge propagation velocity were carried out in several ways: from instant snapshots from the high-speed camera and images of the discharge from a streak-camera. The mechanisms responsible for the propagation of the discharge are currently the subject of further research.