Fluid dynamics in closed cycle pulsed lasers

Several types of repetitively pulsed gas lasers use closed cycle flow systems to minimize gas consumption, eliminate exhaust and provide minimum weight laser systems for long run time applications. The closed cycle flow system must provide gas to the laser cavity with the correct properties and adequate medium homogeneity in an efficient, reliable manner within acceptable size and weight constraints. Research has identified flow system configurations and developed design analyses to meet these requirements in many applications. This paper describes typical closed cycle flow systems for pulsed lasers with their individual components, and several of the techniques that have been used to design and model them. Flow phenomena occurring in closed cycle pulsed lasers are considered with the techniques used to analyze them and the methods developed to control them. Several flow system issues that offer improvements in the performance of closed cycle pulsed laser systems are discussed in the final section.