CW laser beam propagation through a moving stagnation zone

This paper reports the results of an experimental study of the thermal blooming which occurs in a stagnation zone, a region of the propagation path in which there is no net flow of the medium transverse to the laser axis. A stagnation zone results from the cancellation of the relative motion between the laser beam and the air path by a wind and beam slew, and motion of the zone occurs when the latter accelerates. This study considered both stationary and moving stagnation zones and found that their thermal blooming properties can be characterized by a simple expression involving a single parameter whose value is determined by beam and medium properties and encounter kinematics.