Features of the α-γ transition in a low-pressure rf argon discharge

Abstract

It is found that the region for the stable existence of the a regime of a radio-frequency ~rf! discharge is bounded not only on the moderate-pressure side, but also on the low-pressure side. One feature of the a ‐g transition in a low-pressure rf discharge is that the criterion for breakdown of the electrode sheath is not satisfied. It is shown that at low pressures the a ‐g transition of an rf argon discharge takes place abruptly and exhibits hysteresis. At intermediate pressures the a ‐g transition is continuous and lacks jumps; negative differential conductivity appears, double layers form, and nonmonotonic behavior of the plasma density is observed at the center of the discharge. The role of stochastic ~collisionless! electron heating in sustaining an rf discharge at intermediate gas pressures is discussed. © 1998 American Institute of Physics.@S1063-7842~98!01005-8#