Chemical oxygen iodine laser (COIL) beam quality predictions using 3-d Navier-Stokes (MINT) and wave optics (OCELOT) codes

Abstract

This paper describes a series of analyses using the 3-d MINT Navier-Stokes and OCELOT wave optics codes to calculate beam quality in a COIL laser cavity. To make this analysis tractable, the problem was broken into two contributions to the medium quality; that associated with microscale disturbances primarily from the transverse iodine injectors, and that associated with the macroscale including boundary layers and shock-like effects. Results for both microscale and macroscale medium quality are presented for the baseline laser operating point in terms of single pass wavefront error. These results show that the microscale optical path difference (OPD) effects are one dimensional in nature and of low spatial order. A United 1-d analysis was also conducted showing that water condensation also has some influence on the cavity medium quality. The COIL medium quality is shown to be dominated, however, by macroscale effects; primarily pressure waves generated from flow/boundary layer interactions on the cavity shrouds.