Shock wave generation by atmospheric breakdown plasma on a high power millimeter wave beam

Oda, Yasuhisa; Kajiwara, Ken; Takahashi, Koji; Kasugai, Atsushi; Sakamoto, Keishi; Yamaguchi, Toshikazu*; Komurasaki, Kimiya*

The millimeter wave breakdown is an important phenomenon in the transmission technology for the high power millimeter wave beam in the atmosphere. First, the development of the breakdown plasma was visualized using a high speed video camera. Next, the shock wave generated by breakdown plasma was visualized using shadow graph method. A high power millimeter wave beam generated by 170GHz-1MW gyrotron was used. As a result, small luminescence plasma spots formed the ionization front of the breakdown plasma and they propagated in the supersonic velocity. The shock wave was formed in front of the ionization front. The propagation velocity of shock wave was nearly same to the ionization front velocity. This indicates that the shock wave was supported by millimeter wave plasma.