Propagation of High Energy Laser Beams Through Atmospheric Stagnation Zones

摘要

Stagnation zones, i.e., regions in which the effective wind velocity is zero, can greatly enhance the thermal blooming of high-energy laser (HEL) beams in the atmosphere. An expression for the Strehl ratio of a focused HEL beam propagating through a stagnant absorbing region is derived. The propagation of a HEL beam in a maritime atmosphere is numerically modeled in a fully three-dimensional and time-dependent manner. The beam is focused onto a remote target, and a stagnation zone is created by slewing the laser in the direction of the wind. The laser power delivered to the target is calculated as a function of slew rate. For the parameters considered, it is found that a stagnation zone near the laser source has little effect on the propagation efficiency while a stagnation zone near the target can significantly reduce the power on the target.