Hot Plasma and Non-linear Effects in a Weakly Ionized RF Plasma

Recent experiments in a low-pressure inductive RF discharge where the interaction of electromagnetic field with the plasma is governed by electron thermal motion rather than electron-atom collisions are reviewed in this talk. From direct measurement of the plasma RF electric field and current density it was possible to distinguish between the collisional and stochastic regimes of evanescent electromagnetic wave interaction with plasma electrons. New features in the electron energy distribution, wave phase bifurcation and phase velocity reversal, and negative power absorption are found in these experiments and interpreted in terms of non-local electrodynamics due to electron thermal motion. We also found RF currents of doubled frequency (induced by the RF Lorentz force) as well as modification of the plasma space distribution caused by the pondermotive force. These effects found in the experiments with a weakly ionized gas discharge plasma are typical for hot plasma phenomena in fusion reactors and space plasma