Plasma parameter characterization of a reflex plasma source operating in oxygen

A reflex discharge plasma, obtained as a hybrid between a Penning discharge plasma (PDP) and a hollow-cathode discharge (HCD) plasma, is analysed as a possible direction-current, high-density plasma source. The experiment is run in oxygen at pressures of 10 mTorr and 1 mTorr, and for discharge curre nts of 100 to 200 mA. Although the gas pressure is considerably lower than those used in HCDs, the hollow-cathode effect (HCE) occurs for current leve ls higher than 100 mA and leads to plasma densities comparable with those o btained using inductive plasma sources. The presence of a constant magnetic field leads to the enhancement of electron emission from cathodes under io n bombardment, and to the decreasing of the ion loss by diffusion to the wa ll.