The Faraday dark space of a He glow discharge

Abstract

The axial distribution of the plasma parameters in the Faraday dark space (FDS) was measured in the direction moving from the negative glow to the positive column (PC). The axial electric field and the electron temperature increases, whereas the concentration of electrons decreases. The flow of electrons in the FDS consists of a drift flow, diffusion flow, and thermal diffusion flow. Both the diffusion and the thermal diffusion are individually large but as they are in opposite direction their influence on the current is small. The ratio of the anysotropic part f1 in the velocity distribution function of the electrons to the isotropic part f0 is much higher in the FDS than in the PC. This is due to the gradients of the concentration and temperature of electrons in the FDS.