Critical electron density in a self-contained copper vapour laser in the restricted pulse repetition rate

One of the mechanisms of the inversion breaking in copper vapour lasers caused by a high prepulse electron density is considered. Inversion breaking occurs at a critical electron density N_{e cr}. If the prepulse electron density exceeds N_{e cr}, the electron temperature T_{e cr} cannot reach, during a plasma heating pulse, the temperature of ~2 eV required for lasing. A simple estimate of N_{e cr} is made.