BOUNDED, RESONANTLY SUSTAINED HIGH-FREQUENCY PLASMAS IN A MAGNETIC FIELD AND DENSITIES HIGH ABOVE CRITICAL DENSITY

It is shown that the wave properties of a magnetized plasma column, i.e., of a bounded magnetized plasma, at low incident high-frequency power determine the behavior of the column at high hf power. At high hf power, the energy absorbed is sufficient to sustain the plasma in one of its linear (i.e., low-power) resonant states. The plasma can either be sustained in one of its cold plasma resonant states or in its hot plasma resonant states. A partially quantitative theoretical picture can be drawn and maxima of the density as a function of B0 (static magnetic induction) exactly predicted. In this manner densities high above critical density (ωe, > ω; ω is the angular frequency of hf field; ωe is the electron plasma frequency) can be obtained in the neighborhood of the lower cyclotron harmonics and along the upper branch of the cold plasma resonances. Ejection of plasma outside the interaction region between plasma and wave is observed. This ejection gives rise to plasma tongues" with density maxima not correlated to the density of plasma in the interaction region. Low-frequency instabilities and the generation of harmonics are also investigated."