The rapid development of space charge in a thermally produced plasma

Abstract

The response to a voltage step of a thermally produced plasma, bounded by electron-rich sheaths and confined between incandescent-electrodes, is examined. During the lime-scale of interest, 2π/ωpe < t < 2π;/ωP1, the ensemble of plasma ions id virtually frozen, being inertially restrained, while the electrons move in quasi-static electric fields. it is shown that, following the application of a voltage step, there is a rapid development of a positive space-charge layer adjacent to the negative space-charge layer on the cathode. The self-consistent-potential profile between the electrodes is calculated, treating the ions as a stationary uniform background and the theoretical relationship between the step voltage and consequent step current is obtained. The latter shows excellent agreement with experiments in which a transmission line was discharged through the plasma, providing the required fast-rising rectangular pulse.