The behaviour of electrostatic double probes in plasmas with high-amplitude RF fields

Abstract

In experiments, concerned with the RF heating of plasma, the very large high frequency fields (1 kV cm^-1, 1 MHz in these experiments) cause characteristic distortions of the signals of electrostatic double probes and particle spectrometers: The probe current appears as a series of narrow spikes, while the electric fields inside the plasma change sinusoidally with time. A model is presented explaining the experimental observations and allowing the evaluation of the signals with respect to T_e and n_e.