Abstract

We report theoretical investigations of long-wavelength laser mechanisms based on efficient formation of electronically excited atoms or ions by charge exchange. In one promising practical arrangement a plasma containing the ions clashes with a vapor containing the neutral-atom collision partners. If charge transfer wins over competing photo-chemical processes, then inversion of population in an electronically excited state appropriate for lasing results. We present a systematic procedure for determining whether and under what conditions lasing occurs for given collision partners. Via rate equations describing ionic and neutral populations we assess in a first approximation the roles of charge transfer, spontaneous emission from the excited specie, and plasma and vapor pulse shapes in achieving population inversion. We next investigate basic laser action by extending the rate equations to include stimulated emission and photoionization of the excited specie by laser radiation. Our refined analysis is based on detailed studies of the other photo-chemical processes to determine their relative effects on laser action. Where necessary, we perform cross-section calculations for various processes to assess their importance.

© 1982 Optical Society of America