Impracticability of a helium–hydrogen recombination laser excited by a continuously operating electron beam

Theoretical results support the experimentally established failure to achieve recombination lasing from an He–H₂ mixture. An analysis is made of the distribution of the population of the He levels with n = 2. It is shown that the populations of the 2 ¹P and 2 ³P levels (which are the lowest in the postulated lasing transitions) cannot drop below a certain limit when measured relative to the populations of the 2 ¹S and 2 ³S levels. This limit exists because of insufficiently fast deexcitation of the 2 ¹P and 2 ³P levels in collisions with plasma electrons. A study is made of an auxiliary distribution in which the absolute populations of the 2 ¹P and 2 ³P levels are always less than under real conditions. It is shown that even in the presence of such a "favorable" distribution the required population inversion is not established.