The repetitively pulsed argon laser and its application in a hypersonic shock tunnel

A pulsed argon laser at the frequency of 1 kc/sec to 5 kc/sec, each pulse lasting 2.5-5 microsec, was developed in 1973. The laser has a discharge tube consisting of many disks of spectrum-graphite stacked together. This tube is 4 mm in diameter and 600 mm long, and is filled with high pure argon gas at 0.4 torr. The laser beam is polarized and is therefore a good light source for a schlieren interferometer. A series of intense repetitive current pulses is used to drive the argon laser to get a series of pulsed light output. The pulsed argon laser can produce about 100 laser pulses at a repetition rate of 5 kc/sec on a low driving voltage. It can be used as the light source of the optical system for flow visualization, and as the flash lights for free-flight testing in a hypersonic shock tunnel.