Plasma stratification in radio-frequency discharges in argon gas

We conducted experimental studies and computer simulations of standing striations in capacitive coupled plasma in agas. Standing striations were observed at frequencies 3.6, 8.4 and 19.0 MHz, in a pressure range 0.05–10 Torr, tube radius R = 1.1 cm, for a certain range of discharge currents (plasma densities). Numerical simulations revealed similar nature of standing striations in CCP and moving striations in DC discharges under similar discharge conditions. Comparisons to computer simulations with experimental observations helped clarify the nature of these striations. The non-linear dependence of the ionization rate on electron density is shown to be the main underlying mechanism of the stratification phenomena. (letter)