PRELIMINARY CALCULATIONS ON THE PLASMA OF A HELIUM-NEON LASER
Abstract
Calculations are presented on the rf-excited plasma in a laser which generates 15 milliwatts of coherent cw radiation at 11,530 A. Estimates are given of the average electron concentration, the electron energy distribution, the atom temperature, and the populations of the maser levels. The nature of the ambipolar diffusion process in the plasma is treated in some detail. Significant conclusions reaced in the study are discussed. The electron energy distribution differed markedly from a Maxwellian one. If a clean quartz or glass tube were used, it was likely that the atom temperature was markedly higher than room temperature; if so, increasing the thermal accommodation coefficient by coating the inner wall of the tube should improve overall performance. The laser plasma (in a mixture of He at 1 mm Hg and Ne at 0.1 mm Hg) is not amenable to the usual treatment of ambipolar diffusion; in particular, the positive-ion concentration near the wall is not negligible. Increasing the strength and the output impedance of the rf exciter might be beneficial. Consideration of the nature of ambipolar diffusion furnishes a simple explanation of the fact that ion temperatures determined by Langmuir probes in low-pressure gas dischrges are sometimes implausibly high. (Author)
Document Details
- Document Type
- Technical Report
- Publication Date
- Sep 01, 1961
- Accession Number
- AD0265059
Entities
People
- Roy C. Ward
Organizations
- The Aerospace Corporation