High-Density and High-\textit{$\rho $R} Fuel Assembly for Fast-Ignition Inertial Confinement Fusion

Scaling relations to optimize implosion parameters for fast-ignition inertial confinement fusion are derived and used to design fast-ignition targets relevant to direct-drive inertial fusion energy (IFE). A method to assemble thermonuclear fuel at high densities, at high \textit{$\rho $R}, and with a small-size hot spot is presented. Massive cryogenic shells can be imploded with a low implosion velocity $V_{I}$ on a low adiabat \textit{$\alpha $} using the relaxation-pulse technique.\footnote{R. Betti\textit{ et al.}, Phys. Plasmas \textbf{9}, 2277 (2002).} While the low $V_{I}$ yields a small hot spot, the low \textit{$\alpha $} leads to large peak values for the density and areal density. It is shown that a 750-kJ laser can assemble fuel with $V_{I}\approx $ 1.7 $\times $ 10$^{7}$ cm/s, \textit{$\alpha $} $\approx $ 0.7, \textit{$\rho $} $\approx $ 400 g/cc, \textit{$\rho $R }$\approx $ 3 g/cm$^{2}$, and a hot-spot volume less than 10{\%} of the compressed core. If fully ignited, this fuel assembly can produce yields of $\sim $150, of interest to IFE applications. This target can also be shock-ignited with a 250-kJ laser-driven spherically convergent shock yielding a gain exceeding 120. This work has been supported by the U.S. Department of Energy under Cooperative Agreement ER54789 and DE-FC52-92SF19460.