LOW-FREQUENCY INSTABILITY IN WEAKLY IONIZED CURRENT-CARRYING MAGNETIZED PLASMAS .2. BEHAVIOR 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. OMEGA(ci) is similar to nu(i), rho(i) is similar to R (OMEGA(ci) and rho(i) are the ion gyrofrequency and gyroradius, nu(i) 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.