Energy capabilities of a supersonic cw HF laser operated in pulse-periodic regime

A theoretical analysis is made of a two-dimensional gasdynamic model of a self-contained supersonic pulse-periodic HF laser with Q switching. It is shown that additional relaxation and the difference between the rotational quantum numbers of lasing transitions are responsible for the reduction in the specific output energy in the pulse-periodic regime to ~15 – 20%, depending on the pressure in a gas generator, of the output energy in the cw regime. The energy of a pulse per unit area of the nozzle array is ~2.5 × 10^–4 J cm^–2. The pulse duration can be varied in a wide range (at least 10 ns) by a suitable selection of the threshold conditions in the cavity. The pulse repetition frequency, governed by the time needed to replace the active medium over the whole length of the lasing zone, is ~30 – 50 kHz.