Mechanism limiting the pulse repetition frequency of a barium vapor laser

Abstract

An investigation was made of the decay of the metastable 1D2 level of the barium atom in mixtures with the buffer gases helium and neon. Measurements were made of the constants for deexcitation by electrons and barium atoms in the ground state, which were found to be 0.7×10−7 and 1.6×10−11cm3/sec. The double and regular pulse method was used to study the dependence of the laser output energy on the pulse repetition frequency. The results of measurements of the population of the 1D2 level in the afterglow, and also of a study of its influence on the lasing parameters demonstrated that the reduction in the laser output energy, both during the second pump pulse and when the repetition frequency was increased in the regular pulse regime, was due to a high electron density before a pulse. The probability of the radiative transition 1P10–1D2 was measured and found to be 0.9×105sec−1. It was concluded that the barium vapor laser is collisional and can generate long laser emission pulses by depopulating the metastable level during deexciting collisions with barium atoms in the ground state and with the walls of the tube.