Chemical oxygen-iodine laser with a cryosorption vacuum pump

In a chemical oxygen-iodine laser (COIL), chemically prepared, gaseous gain medium at 3-10 Torr pressure is drawn through the laser cavity by vacuum suction. Multiple-stage vacuum pumps such as Roots blowers or steam ejectors are typically used to receive and compress the gas flowing from the laser and exhaust it to the atmosphere. The size and weight of such vacuum pumps present a significant challenge to engineering and packaging a transportable COIL system. This work describes COIL systems that use a cryosorption vacuum pump to provide vacuum and safely contain laser exhaust gas. The pump consists of a gas chiller and a bed of zeolite. Gas exhausted from COIL laser cavity is first chilled to about 100 K and condensable vapors are removed. Cold and dry gas is then adsorbed onto a bed of zeolite cooled to a temperature of approximately 80 K. When the sorption capacity of the zeolite is exhausted, the pump can be regenerated by allowing the zeolite and the gas chiller to warm up and liberate trapped gases. Gases liberated in the regeneration process are removed by a small mechanical vacuum pump. The cryosorption pump is a compact lightweight device, which can provide effective vacuum pumping for transportable COIL systems.