A REPETITIVELY PULSED CARBON DIOXIDE LASER WITH MEAN POWER OUTPUT IN EXCESS OF 30 kW

Abstract
A pulsed electron beam sustained atmospheric pressure carbon dioxide laser with an active volume of 17 litres has been incorporated in a closed cycle gas recirculation system. Gas flow and electrical input can be varied over a wide range. The problems associated with repetitive operation have been explored and measurements made of multimode and single mode output quality, reproducibility and reliability. Particular attention has been given to electron gun and foil window design, and the mechanical stability of the optical cavity. The effect of gas purity, gas flow rates and damping of acoustic disturbances have been measured. Medium quality has been assessed by pulsed interferometry and a time lapse cine film made of the decay of perturbations in the inter-pulse period. Maximum multimode output at 10.6 µm is 600 J per 30 microsecond pulse with pulse repetition frequencies up to 66 Hz. Mean power achieved has been up to 36 kW for 0.5 second or 22 kW for 1 second duration with the capability of repeating the pulse train at 30 second intervals.