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--H/sub 2/ 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 /sup 1/P and 2 /sup 3/P 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 /sup 1/S and 2 /sup 3/S levels. This limit exists because of insufficiently fast deexcitation of the 2 /sup 1/P and 2 /sup 3/P levels in collisions with plasma electrons. A study is made of an auxiliary distribution in which the absolute populations of the 2 /sup 1/P and 2 /sup 3/P 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.