Growth of arc in high-pressure, pulsed glow discharge by gas density depletion

Abstract

Effects of gas density depletion on arc formation of high-pressure, pulsed glow discharge have been investigated by eliminating the other factors which may affect the discharge stability, such as shock waves, residual ions, electrode heating, and discharge products. The gas density depletion has been simulated by utilizing a subsonic gas flow between the curved electrodes combined with a convergent nozzle and a divergent diffuser. A comparison has been made on the discharge in the aerodynamically created gas density depletion with the second discharge in the double-pulse discharge within a stable gas. We have found that the large gas density depletion, Δρ/ρ0∼−3.6% corresponding to a pulse repetition rate (PRR) of ∼50 Hz, tends to cause an arc-like filament or an arc without the shocks, ions, electrode heating, and products. However, the second discharge in the double-pulse discharge becomes an arc in much smaller gas density depletion (Δρ/ρ0∼−1.2% corresponding to PRR ∼3 Hz). Therefore, the collapse of high-pressure, pulsed glow discharge is most likely caused by some factor other than the gas density depletion.