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 cathodic are are presented. The are is operated at a current level of 100 A, with a copper cathode, and with oxygen gas at a pressure of 0.5 Pa. The employed diagnostics include spherical Langmuir probes and a calorimetric technique. The plasma potential, electron temperature, ion density, and ion kinetic energy are inferred at different axial positions in the discharge chamber. In order to explain the obtained experimental results, a simplified one-dimensional 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 neutral gas molecules and lateral diffusion loses of energetic particles are included in the theoretical treatment. (C) 2001 American Institute of Physics.