Formation and decay processes of Ar/He microwave plasma jet at atmospheric gas pressure

Dynamic behaviors of gas/plasma mixture generated by microwave discharge jet at atmospheric pressure have been investigated in terms of the effects of working gas dynamics on the discharge characteristics, focusing on the following four points: formation of discharge jet at the ignition phase, growing speed of plasma plume in relation to gas flow rate, acceleration and deceleration of upward movement of plasma plume, and decay process of plasma column at turn-off of microwave power. Four stages are identified at the discharge ignition. The acceleration coming from buoyancy effect and the deceleration due to gas flow turbulence have been found. The decay speed of plasma column at a power shut-off is found to be influenced by the gas flow turbulence and the recombination rate. (C) 2011 American Institute of Physics. [doi:10.1063/1.3622302]