Conceptual design of a 170-MJ hydrogen fluoride laser for fusion

Abstract

We have completed the conceptual design of a 170-MJ laser system consisting of two identical, opposing, 0·4 M-litre, 84-MJ HF subsystems, which together deliver 105 ‘useful’ MJ in 50 ns (FWHM duration) to a laser-fusion target during its hydrodynamic drive interval. We achieved extreme design simplicity by eliminating most optics, using an inexpensive, very-high-energy-density gain medium, propagating the laser beam at the maximum fluence permitted by optical breakdown in the laser medium, and by using replicated simple subsystems for pulsed power. The infrared spectrum of the HF laser lies outside the ultraviolet range favored by the U.S. laser fusion program for optimum target coupling efficiency. However, the laser architecture we describe is an alternative for laser fusion systems which offers dramatic improvements in simplicity, compactness, and efficiency, which advantages will be even more pronounced when equally efficient, visible-wavelength chemical lasers become available.