Possible new lasers based on plasmas similar to thermionic converters

This paper describes novel plasma recombination lasers that can be produced with conditions similar to the plasma in a thermionic convertor. Calculations have shown that a population inversion can be obtained by either time variation of the current in a thermionic converter discharge or by gas dynamic expansion of plasma flow driven by heat pipe action. Sudden modulation of the current can cool the plasma in a thermionic convertor with electrons coming from the thermionically emitting electrode to produce an inversion of the 7p‐7s line in cesium. Alternatively, if the inter‐electrode plasma is made to flow through a supersonic expansion nozzle, a population inversion in the downstream plume may also be produced. Either of theses approaches or a combination of them can be used to convert heat directly into laser output. Two laser lines in the cesium vapor at 2.93 and 3.10 microns are predicted. Two other novel laser concepts are also mentioned: a solar pumped atmospheric laser and a laser based on the spac...