Low-frequency instability in weakly ionized current-carrying magnetized plasmas. Pt. 2: Behaviour in high-frequency wave field

The effect of the Trivelpiece-Gould mode on the behaviour of a low-frequency drift instability in a weakly ionized magnetized plasma is studied experimentally in a DC argon discharge. The ions are weakly magnetized, i.e. Ωci ∼ νi, ρi ∼ R (Ωci and ρi are the ion gyrofrequency and gyroradius, νi is the ion-neutral collision frequency and R is the plasma radius). With increasing amplitude of the high-frequency field, the frequency and the amplitude of the instability decrease. Since the anomalously enhanced ambipolar field is considered as a very important factor in the mechanism driving the instability, special attention is paid to its variation with increasing high-frequency power. The nonlinear mechanisms of the dynamical control of the instability are discussed. (author)