Effect of matching of a power supply with a laser tube and of pumping conditions on the relaxation of metastable states and the frequency – energy parameters of a copper vapour laser

The relation between the lasing efficiency of a copper vapour laser and relaxation of the metastable states is studied at high average pump powers. The prepulse concentration N_ms0 of metastable states in tubes of diameter 2 cm in lasers with a high efficiency (above 1%) is shown to be negligible up to linear output powers of ~50 W m^-1 and has no effect on the output power. At a lower lasing efficiency caused by the mismatch between a power supply and the laser tube, the population of metastable states strongly increases during afterglow and can become a main factor restricting the output power in a repetitively pulsed regime. As the neon pressure is increased or hydrogen is added, the matching is facilitated and the effect of N_ms0 on the lasing parameters of a high-power copper laser decreases.