Optical Emission From Oxygen Plasma in E and H Modes

Highly reactive oxygen plasma with a very high dissociation fraction of oxygen molecules is often created in electrodeless discharges. The discharge runs either in the E or H mode. The E mode is obtained at low power while the H mode dominates at high power. The transition between two modes is easily observed by the naked eye or, even better, by optical emission spectroscopy. In this paper, we show major differences between the two modes obtained in an experimental plasma reactor with a 1200-W RF generator operating at the frequency of 13.56 MHz.