Copper Vapor Laser Scale Demonstration

A pulsed copper vapor laser has been successfully scaled to 10 cm diameter. A computer simulation model of the pulsed copper vapor laser in both helium and neon buffers was developed and validated. It projects output pulse energy at 510.5 nm of over 0.33 joules and efficiency of over 2.5% from a 10 cm diameter laser running at 200 HZ, in neon. The key to such operation is the decay of ionization and gas heating during the long interpulsed period and the application of high voltage for reliable breakdown. This minimizes skin effect limitations and increases electron temperature. A flexible large bore laser test facility was built using glow discharge heating and burst mode excitation. Preliminary tests with a 4 1/8 in. diameter laser were fully successful. Glow discharges could heat the laser to the 1400 deg C-1500 deg C range and pulsed discharges filled the full bore. Pulse to pulse reproducibility could be achieved at 200 HZ after only two pulses if voltages of 36 KV were applied to the storage capacitor. The specific loading in these tests was several millijoules per cu cm, the range projected by the model as necessary for high energy output. Laser operation was also demonstrated filling essentially the full bore. Estimates of unoptimized output energy in helium were in the range of greater than 70 millijoules, the highest ever reported from a pulsed metal vapor laser. These results were consistent with computer simulations. Measured current and voltage waveforms agreed very closely with computer generated plots.