Experimental studies of high pressure RF discharges

Abstract

Summary form only given, as follows. Experimental studies on RF discharges at 13.56 MHz have been performed at very high gas pressures between 1 Torr to atmospheric pressure. Plasma parameters, comparable to low pressure discharges, are estimated in He discharges by optical emission spectroscopy and Langmuir probe measurements. The estimated electron density of 1-10/spl times/1011 cm-3 and electron temperature of 1-2 eV is consistent with a 1-D model of plasma impedance and particle balance. The plasma conditions change substantially as oxygen is introduced into the discharge. A decrease in electron density is observed, which is attributed to the electronegativity of oxygen. In addition, formation of oxygen atoms and metastable oxygen molecules is observed by optical emission spectroscopy. A further increase in the oxygen flow results in the extinction of the discharge or arcing. A detailed analysis of the experimental results will be presented.