1. Plasma Heating Technology Group, Naka Fusion Institute, Japan Atomic Energy Agency, Naka, Ibaraki, 311–0193, Japan 2. Department of Advanced Energy, The University of Tokyo, Kashiwa, Chiba, 277–8561, Japan
Abstract:
A shock wave supported by an atmospheric breakdown plasma caused by a high-power millimeter-wave beam was studied. The shadow
graph image in a shock tube visualized the one-dimensional shock-wave generated by the millimeter-wave breakdown in atmosphere
for the first time. It was revealed that a normal shock wave propagated through the tube at the constant velocity while it
was detached from the ionization front of the plasma whenever the propagation velocity of the ionization front was supersonic
or subsonic. And it was visually clarified that the atmospheric millimeter-wave breakdown had the combined structure of the
normal shock wave and the heating region of the millimeter-wave plasma. The measured pressure of the shock front was as equal
as the normal shock which propagated at measured Mach number.