Analysis of a Cu-Ne hollow cathode glow discharge at intermediate currents

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Abstract
In a copper-neon hollow cathode glow discharge the authors have measured several parameters. At pressures between 250 and 1000 Pa and cathode current densities between 0.01 and 0.1 A cm-2 the authors obtained gas temperatures between 900 and 1400K with use of Doppler broadened line profiles. The electron transport temperature was obtained from the time dependent optogalvanic effect to be 0.2 to 1.2 eV. Electron densities were derived from Stark broadening of line profiles recorded with saturated absorption spectroscopy; values were between 1 and 9*1019 m-3. Copper ground state densities have been found with the absorption of resonance radiation and were between 0.2 and 6*1019 m-3. Densities of several excited states, including the neon metastables, were measured with the absorption of dye laser radiation; metastable density was of the order of 1018 m-3. They are compared with values obtained from a collisional radiative model. It turns out that ionisation and excitation of neon is caused by beam electrons, ionisation of copper occurs by charge transfer and loss of ions is caused by ambipolar diffusion only. These processes are incorporated in a transport model which has been solved using a sputtering condition at the cathode boundary. In this sputtering condition thermal diffusion of copper atoms and the sticking coefficients of copper atoms and ions are included. The results of the model are in good agreement with the measurements.

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