High-Intensity Shock-Ignition Experiments in Spherical and Planar Geometry

Shock ignition\footnote{R. Betti\textit{ et al.}, Phys. Rev. Lett. \textbf{98}, 155001 (2007).} has recently gained much attention as an inertial confinement fusion concept that assembles thermonuclear fuel to high areal densities and then ignites it by launching a strong shock wave into compressed fuel. OMEGA experiments study the shock-ignition concept using various types of adiabat-shaping laser pulses and a high-intensity spike. High-intensity laser--plasma interaction experiments in spherical and planar geometries provide valuable data on backscattering, fast-electron generation, and shock-wave timing for intensities $>$1 $\times $ 10$^{15}$ W/cm$^{2}$. A significant energy transfer into fast electrons was measured with hot-electron temperatures $>$100~keV in planar targets and $\sim $50 keV in spherical targets. This work was supported by the U.S. Department of Energy Office of Inertial Confinement Fusion under Cooperative Agreement No. DE-FC52-08NA28302.