Instabilities of Ar/SF6 inductive plasma discharges

Relaxation oscillations are studied in three low-pressure inductive plasma discharges operated with argon and sulfur hexafluoride gas mixtures. Two distinct phenomena, downstream instabilities and source oscillations, occur in certain domains of gas pressure, radio frequency power, and electronegative gas chemistry. The downstream instabilities develop at some location well below the plasma source. They are consistent with ion two-stream instabilities, in inductively coupled plasmas (ICPs) with sufficiently long downstream regions. Source oscillations consist of large amplitude density variations within the ICP plasma. They are consistent with capacitive to inductive mode transitions, in ICPs with sufficiently large capacitive currents. (C) 2003 American Institute of Physics.