Laser Fusion Studies at NRL.

Abstract : The NRL group is studying the technical feasibility of high gain laser fusion pellets driven by low irradiance (10 to the 14th power W per sq cm) multi-nanosecond lasers. In earlier experiments, it was shown that both absorption and hydrodynamic efficiencies were consistent with high gain pellet designs. In addition to extending this work to greater intensities and larger spot sizes, research is underway on the origins and magnitude of target preheating at low irradiance, on experimental and theoretical work on the issue of symmetry and into the related questions of Rayleigh-Taylor instability and mixing of layers in multi-layer targets. Substantial progress has been made in all of these areas: the rear surfaces of slab targets have been ablatively accelerated to velocites above 10 to the 7th power cm/sec with acceptably low levels of preheat and there is experimental evidence of smoothing of spatial non-uniformities in the laser profile on a transverse scale of 100 micrometers or less. (Author)