Capacitive discharge mode transition in moderate and atmospheric pressure

Current-voltage characteristics of alpha- and gamma(-)modes were investigated in moderate and atmospheric pressure capacitive discharges. The alpha- and gamma-modes, the co-existence of both modes, and the alpha- to gamma- and gamma- to alpha-mode transitions were observed with the changes in voltage, current, and plasma volume. Changing of gas pressure, (100-760) Torr, the alpha to gamma and the gamma to alpha transition occurred with respect to input power increasing and decreasing, respectively. The hysteresis in current and voltage curve was observed and became more evident at higher pressure. Using a simple electrical circuit model, the relation between the gas pressure and the alpha-sheath thickness before mode transition was described. (C) 2008 Elsevier B.V. All rights reserved.