Comparison of Kr and Xe flashlamps for Nd:YAG lasers

Linear krypton and xenon flashlamps (6-mm bore, 3-inch arc) having various fill pressures between 450 torr and 4 atm have been operated in a single elliptical gold-plated pump cavity to excite a Nd:YAG laser rod (0.25-inch diameter, 3 inches long). Here we describe laser operation as a function of lamp fill, for electrical input energies ranging from 2 to 40 joules (120-μs pulse duration) and for pulse repetition rates from single shot to 20 Hz. We have found that Kr lamps are generally superior to Xe lamps for pumping Nd: YAG except at high current densities. Specifically, for this system (the parameters of which are suitable for commercial and military applications), the optimum Kr fill pressure is approximately 700 torr, while the optimum Xe fill pressure is roughly 1000 torr. The threshold with the 700-tort Kr lamp is 58 percent of that with the 1000-torr Xe lamp; the crossover energy (for equal absolute efficiencies) is 40-joule input, which in our system corresponds to about 375-mJ output.