HIGH POWER GAS LASER RESEARCH.

The report concerns the investigation and optimization of high power and high efficiency in the cw gas laser utilizing carbon dioxide, nitrogen and helium as the active laser medium. In all cases, the gases are excited by an electrical discharge. In the area of flowing gas lasers, an experimental investigation was made into the unsaturated gain characteristics at 10.6 microns and their dependence on the tube diameter, gas mixing, and flow speed. The measurements were taken with a laser bridge of sufficient resolution to measure the radial profiles of the gain. For the high-power oscillators, determination was made of the dependence of the power on tube length, gas pressure, pumping speed, output coupling, and mode control. For sealed-off lasers, determination was made of the dependence of the output power on the gas mix, pressure, and tube preparation. Some results on the initial phases of long life tests are also included. Much of the data which was accumulated indicates that the present limitations of output power in large bore tubes and sealed-off tubes stem from the heating of the gas by the discharge. This is corroborated by theoretical calculations of the heat transfer and temperature profile in the tube. Author