The possibility of pumping molecular CO2 lasers (X = 10.6 qm) with nuclear radiation was considered in many studies in the early stages of NPL research (see Chap. 1, Sect. 1.1). Despite the numerous experiments, attempts to pump CO2 lasers with nuclear radiation yielded negative results. Experiments [152] to excite a 3He-N2-CO2 mixture with nuclear reaction products 3He(n, p)3H showed the absence of gain at the 10.6 qm line in a wide range of changes in the total pressure (0.26-0.8 atm) and composition of the mixture. In these experiments, absorption of radiation of the probe laser with X = 10.6 qm was observed, which testifies to the predominant populating of the lower laser level when a CO2 laser is pumped with high-energy charged particles. Calculations [153] of kinetic processes in the He-N2- CO2 plasma also confirm the ineffectiveness of direct pumping of CO2 lasers with nuclear radiation.

Another variation of pumping the CO2 laser with preliminary excitation of a nitrogen molecule and subsequent transfer of energy from these molecules to CO2 molecules was implemented in experiments reported in reviews [126, 154]. A diagram of the experiments is shown in Fig. 3.6. Nitrogen passing through a tube with a layer of 10B at a velocity of 7.6 x 10-4 m3 s-1 was excited by the nuclear reaction products 10B(n, a)7Li in the neutron flux of a pulse reactor with a pulse duration of about 200 qs (Фтах = 5 x 1016 cm-2 s-1). Then the excited nitrogen was mixed in the laser cavity with CO2 and He. The laser radiation arose within 30 ms after the reactor pulse and had a power of about 100 W with a laser pulse duration of about 1 ms.