Modeling of high-pressure, high-frequency (RF) oxygen plasmas

A numerical model has been developed to simulate oxygen high-frequency (RF) plasmas at pressures of 1 and 5 atm. In contrast to argon plasmas at 1 atm, oxygen plasmas separate from the walls of the reactor tube and concentrate more toward the center of the tube. This effect is even more pronounced at 5 atm. As the power dissipation in the plasma increases, the plasma volume also increases, both radially and axially, without significant increase of the maximum temperature. Insertion of a water-cooled injection probe along the center of the reactor tube causes severe quenching of the oxygen plasma in contrast to argon plasmas which are insensitive to such probes. This indicates that injection of reactants into RF oxygen plasmas by means of water-cooled probes imposes problems due to the sensitivity of oxygen plasma to the presence and location of the probe in the plasma.