Abstract

The excimer-pumped alkali laser (XPAL) system has recently been demonstrated in several different mixtures of alkali vapor and rare gas. Without special preventive measures, plasma formation during operation of XPAL is unavoidable. Recent advancements in the availability of reliable data for electron impact collisions with atoms and molecules have enabled development of a complete reaction mechanism to investigate XPAL-induced plasmas. We report on pathways leading to plasma formation in an $\mathrm{Ar}/{\mathrm{C}}_2{\mathrm{H}}_6/\mathrm{Cs}$ XPAL sustained at different cell temperatures. We find that depending on the operating conditions, the contribution of electron impact processes can be as little as bringing the excitation of Cs(${}^2\mathrm{P}$) states to higher level ${\mathrm{Cs}}^{**}$ states, and can be as high as bringing Cs(${}^2\mathrm{P}$) excited states to a full ionization. Increasing the input pumping power or cell temperature, or decreasing the ${\mathrm{C}}_2{\mathrm{H}}_6$ mole fraction leads to electron impact processes dominating in plasma formation over the energy pooling mechanisms previously reported in literature.

© 2017 Optical Society of America

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