Development of a Polar Drive Shock Ignition Platform on the National Ignition Facility, Lawrence Livermore National Laboratory Technical Report, LLNL-TR-432811 (May 2010), Livermore, CA, USA

Shock ignition, a new concept for igniting thermonuclear fuel [1], offers the possibility for a near-term test of high-gain inertial confinement fusion on the National Ignition Facility at less than 1MJ drive energy [2] and without the need for new laser hardware [3]. In shock ignition, compressed fusion fuel is separately ignited by a strong late-time laser-driven shock and, because capsule implosion velocities are significantly lower than those required for conventional hotpot ignition, fusion energy gains of ~60 may be achievable on NIF at laser drive energies around ~0.5MJ, extending to ~100 at 1MJ. Because of the simple all-DT target design, its in-flight robustness, the potential need for only 1D SSD beam smoothing, minimal early time LPI preheat, and use of present (indirect drive) laser hardware, this target should be easier to field on NIF than a conventional direct-drive hotspot ignition target [3]. A key immediate need is to determine the adequacy of low-mode drive uniformity and shock symmetry under NIF polar drive for the convergence ratios envisaged for these targets. Accordingly, we propose a set of phased experiments employing room temperature hydro-equivalent CH shells to (a) optimize NIF polar-drive symmetry and shock coupling under a combination of beam repointing, partial defocusing and phasing the time-dependent power balance from quad to quad, and (b) characterize the resulting laser-plasma interactions. The objective is to determine the optimum laser drive specifications that will then enable the fielding of a full cryogenic high-gain shock-ignition target on NIF ca. 2014.    [1] R. Betti , C.D. Zhou , K.S. Anderson , L.J Perkins, A.A. Solodov, “Shock Ignition of Thermonuclear Fuel with High Areal Density”, Phys. Rev. Lett., 98, 155001 (2007)        [2] L.J. Perkins, R.Betti, K.N. LaFortune, W.R., Williams, “Shock Ignition: A New Approach to High Gain Inertial Confinement Fusion on the National Ignition Facility”, Phys. Rev. Lett., 103, 045004 (2009)      [3] L.J.Perkins, R.Betti, G.Schurtz, R.S.Craxton, A.M.Dunne, K.LaFortune, A.Schmitt, P.McKenty, D.Bailey, M.Lambert, X.Ribeyre, W.Theobald, D.Strozzi, ,D.Harding, A.Casner, S.Atzeni, G.Erbert, K.Andersen, M.Murakami, A.Comley, R.Cook, R.Stephens, “On the Fielding of a High Gain Shock Ignited Target on the National Ignition Facility in the Near Term”, Lawrence Livermore National Laboratory Technical Report, LLNL-TR-428513, April 2010