Reactor pumped laser research at the Sandia National Laboratories pulsed reactor facilities

Sandia National Labs has been investigating concepts for high power lasers pumped directly by fission energy. The direct pumping of laser media with fission fragments offers the potential advantages of scaling to high powers and very long run times in a compact, self powered system. To investigate the potential of this concept, extensive experiments have been conducted in the Annular Core Research Reactor (ACRR) and the Sandia Pulsed Reactor (SPR-III). These experiments include laser physics tests, radiation effects tests on optical materials, and experiments to examine the scaling of reactor pumped lasers to high powers. The SPR-III is a U-10%Mo fast burst reactor which is used for laser physics experiments. SPR-III is capable of 70 to 1500 μs FWHM pulses generating up to several kW/cc excitation in a liter size laser cavity. The pulse widths greater than a few hundred microseconds are achieved using a pulse stretcher consisting of gram amounts of fissile material surrounded by moderator. The ACRR is a UO2BeO fueled epithermal reactor which is used for larger volume scaling and beam quality experiments. ACRR operates in both steady state and pulsed modes with pulse widths of 7 to 250 ms resulting in excitation rates of ∼2 to 100 W/cc in excitation volumes of up to 50 1. Experimental configurations on both reactors have included central cavity and external cavity locations. The experiments on SPR-III have defined optimum conditions for efficient reactor pumping of rare gas lasers. This information has been used to define scaling experiments now in progress in the ACRR