A chemical oxygen-iodine laser (COIL) comprises an oxygen generator and a nozzle for accelerating generated oxygen to a high or supersonic velocity. A laser cavity is coupled to the nozzle, wherein the accelerated fluid, with injected iodine, is employed as a laser gain medium. A Brayton cycle outlet pump employs the accelerated oxygen and iodine as a component of a process fluid in a Brayton cycle to raise the static pressure of the accelerated fluid to ambient conditions. The Brayton cycle pump comprises a compressor having an inlet and an outlet, the inlet being coupled to the laser cavity to receive and compress accelerated oxygen. A combustor is coupled to the outlet of the compressor to receive compressed oxygen and ignite and combust it A turbine is coupled to the outlet of the combustor to expand the ignited and combusted gas, wherein the turbine powers the compressor. Multiple reheat stages may be used and regeneration and intercooling may also be used. The use of reheat, regeneration, and intercooling depends on the application.