High repetition rate high power xenon-ion laser

A high power pulsed xenon-ion laser has been developed as an optical transmitter for underwater audio communication systems. Performance and design characteristics are: peak power, watts; pulse length, seconds; pulse repetition rate, 2 kHz; laser length, less than 36 inches; input power, less than 10 KW. To achieve the high peak power in this short length, a large bore (20 mm) discharge tube was employed. The use of the large bore, however, introduced problems which include: peak currents are in excess of amperes; optimum anode voltage are of the order of 10 KV, thus introducing hold-off problems. Optimum fill pressures are of the order of 5 microns, thus introducing triggering and lifetime problems. Without pressure control, the operating lifetime of the laser was less than one minute due to gas clean-up. With cryogenic pressure control this lifetime was extended indefinitely. Simple cold cathode and anode configurations were used, however, external switching was required to prevent free-running of the laser. The thyratron switching technique employed eliminated the necessity of a separate trigger and also led to a factor of two improvements in laser efficiency by preventing ringing of the laser current waveform. Details of the laser construction and performance, the electronic circuitry and component difficulties will be presented.