Characterization of plasma-gas interactions in a copper cathodic are operated in oxygen

Several results on the plasma-neutral gas structure generated in a de catho dic are are presented. The are is operated at a current level of 100 A, wit h a copper cathode, and with oxygen gas at a pressure of 0.5 Pa. The employ ed diagnostics include spherical Langmuir probes and a calorimetric techniq ue. The plasma potential, electron temperature, ion density, and ion kineti c energy are inferred at different axial positions in the discharge chamber . In order to explain the obtained experimental results, a simplified one-d imensional stationary model to describe the plasma-neutral gas structure is developed. A good agreement is found between the experimental data and the theoretical predictions when charge-exchange between metallic ions and neu tral gas molecules and lateral diffusion loses of energetic particles are i ncluded in the theoretical treatment. (C) 2001 American Institute of Physic s.