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

Effects of gas density depletion on arc formation of high-pressure, pulsed glow discharge have been investigated by eliminating the other factors whic h may affect the discharge stability, such as shock waves, residual ions, e lectrode heating, and discharge products. The gas density depletion has bee n simulated by utilizing a subsonic gas flow between the curved electrodes combined with a convergent nozzle and a divergent diffuser. A comparison ha s been made on the discharge in the aerodynamically created gas density dep letion with the second discharge in the double-pulse discharge within a sta ble gas. We have found that the large gas density depletion, Delta rho/rho( 0)similar to-3.6% corresponding to a pulse repetition rate (PRR) of similar to 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 t he double-pulse discharge becomes an arc in much smaller gas density deplet ion (Delta rho/rho(0)similar to-1.2% corresponding to PRR similar to 3 Hz). Therefore, the collapse of high-pressure, pulsed glow discharge is most li kely caused by some factor other than the gas density depletion. (C) 2000 A merican Institute of Physics. [S0021-8979(00)06621-4].