FLAMEOUT IN REPETITIVELY PULSED CHEMICAL LASERS.

In an atmospheric pressure, repetitively pulsed, subsonic flow chemical laser, H//2 (D//2) and F//2 gases mixed upstream of the lasing region must remain unreacted until the volumetric initiation occurs. To achieve this, a slug of H//2-free gas flow was provided to isolate the burnt mixture from the incoming fresh mixture by briefly switching off the flow of H//2 between pulses. Fluidic bistable amplifiers were used to do the switching. A switching time of 0. 4 msec was obtained. Flameout was achieved at 60 pps with mixtures containing up to 8% H//2 and 30% F//2 (in He) by volume.