Imprint sensitivity study for high-yield laser direct drive

Future LDD ICF facilities will require mitigation of LPI to achieve high ablation pressure and control of the laser imprint to maintain shell integrity in implosions that achieve high (>100 MJ) yields.  High-bandwidth broadband lasers combined with novel imprint smoothing techniques are believed to allow achieving both requirements. In this study, we use multi-dimensional rad-hydro codes Draco and Hydra combined with highly realistic laser speckle model which uses Fourier optics to calculate laser spots that include the speckle and its time variation caused by the smoothing schemes to simulate the MJ-implosion performance. We compare novel and conventional smoothing methods (Induced Spatial Incoherence and 2D Smoothing by Spectral Dispersion). We also come up with a recommendation for the level of smoothing performance that will be required to achieve near 1D performance. This work was supported by the U.S. This material is based upon work supported by the Department of Energy National Nuclear Security Administration under Award Number DE-NA0004144, the University of Rochester, and the New York State Energy Research and Development Authority and under the auspices of the Lawrence Livermore National Security, LLC, (LLNS) under Contract No. DE-AC52-07NA27344

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