Active diffuser- AD has been developed by blowing in the high pressure gas from small scale nozzles along the
laser chamber walls. Blowing has stabilized boundary layers, decreased its thickness and prevented its separation. So AD
operating has stabilized the gas flow parameters in resonator and localized the zone of slow down of laser flow -
pseudoshock - after laser chamber. So regular shock - wave structures (X-type shocks) that could degrade the flow
optical quality don't appear in resonator.
The use of AD allows developing PRS on base of single-stage ejector with high ejection coefficient (usually
ground -based COIL PRS consist from passive diffuser and two-stage ejector and has low ejection coefficient).