Study of the cathode region of a short glow discharge in oxygen

Summary form only given. A theoretical model of the cathode region of a short glow discharge is presented, based on the concept developed by Kolobov and Tsendin (1992). According to the model, the cathode region is separated into three zones: the cathode voltage fall (CF), the negative glow (NG) and the Faraday dark space (FDS). Three groups of electrons are considered, fast, intermediate and trapped. The fast electrons are described by the continuous-energy-loss approximation, the electron impact ionization and attachment being the corresponding sources and losses. The spatial distributions of charged particles in CF are obtained through the Poisson equation, those in the NG are the solutions of the set of balance equations describing transport of various plasma components and possible plasmochemical processes. Ionization in CF dominates over attachment, therefore the negative ion concentration in CF is small. In the CF and FDS regions, the attachment and detachment processes control the balance of negative ions trapped in the potential well. Attachment is not very effective at low electron temperatures, therefore the negative ion concentration in oxygen and its mixtures with other gases is much less then the electron concentration. In addition to theoretical calculations, the positive and negative ion concentrations, the electron energy distribution function and the electric field distribution have been measured in a short oxygen discharge using probe diagnostics.