Stationary Double Layers in a Collisionless Magnetoplasma

Abstract

Stationary double layers are generated in a magnetoplasma by applying potential differences between two heated plates on which the plasma is produced by surface ionization. Their potential drop φ_D is varied over a wide range eφ_D⁄T_e\simeq1–2×10³ (T_e: electron temperature in eV) without any influence from volume ionization of the background gas. There are always spiky fluctuations especially on the low-potential tail of the double layer. By measuring the double-layer formation process, a localized potential drop is found to be formed initially in front of the plate on the low-potential side, being accompanied with current limitation. This localized potential drop moves along the plasma column, but finally stops and results in the formation of the stationary double layer in the presence of sufficient plasma supply from the plate on the high-potential side.