The kinetics of copper HyBrID lasers

Abstract

Spatially and temporally resolved measurements of many of the parameters of a 25mm bore, 800mm active length copper HyBrID laser have been performed. The laser was operated under excitation conditions for maximum efficiency of light generation at all times. The hook method has been used to investigate the population densities in the copper ground state, the upper laser levels, the lower laser levels and one of the quartet levels in copper. The population density in one of the neon metastable levels has also been measured. All of these measurements have been performed with 5 ns time resolution and 2 mm spatial resolution. A two wavelength laser interferometric technique has been used to measure the electron density with nanosecond time resolution and 2mm spatial resolution. The waveforms of the voltage across the laser head and current through the laser tube have been measured. The temporally resolved laser pulse radial profile has been investigated. The results from these investigations have been compared to those for a 42 mm bore CVL previously studied with the same experimental apparatus. Comparison has also been made with a detailed computer model of a 19mm bore CVL. Deductions as to the effect of the remanent electron density prior to the excitation pulse on the current and voltage waveforms have been made. The effect of added HBr has been discussed, relative to the remanent electron density. The laser kinetics are discussed in terms of the electron temperature and the relative rate coefficients of the mechanisms affecting the level populations.