Mechanism limiting the optimal output pulse repetition frequency of metal vapor self-terminating lasers

Comparative investigations were made by the method of double-pulse excitation of a lead vapor laser (λ = 0.723 nm) with electron-beam and gas-discharge pumping. The time τ at which lasing in the second pulse begins to weaken in the case of electron-beam pumping is determined by the deexcitation rate of the metastable level and is roughly equal to 1 μsec. In the gas discharge laser the reduction in the output power starts at τ ≈ 0.1 msec and is determined by the plasma recombination rate. The specific output energy of the electron-beam laser is double that of the discharge laser, the physical efficiency is an order of magnitude higher, and the optimal pulse repetition frequency is two orders of magnitude higher. The average output power of the electron-beam laser can reach 400 W/m. In copper and manganese vapor discharge lasers the optimal pulse repetition frequency is also determined by the plasma recombination rate.