Progress toward Ignition with Noncryogenic Double-Shell Capsules

Abstract

Inertial confinement fusion implosions using capsules with two concentric shells separated by a low density region (double shells) are reported which closely follow one dimensional (1D) radiatively driven hydrodynamics simulations. Capsule designs which mitigate Au M-band radiation asymmetries appear to correspond more closely to 1D simulations than targets lacking mitigation of hohlraum drive M-band nonuniformities. One capsule design achieves over 50% of the unperturbed 1D calculated yield at a convergence ratio of 25.5, comparable to that of a double-shell design for an ignition capsule at the National Ignition Facility.

Rayleigh-Taylor and Richtmyer-Meshkov instabilities and mixing in stratified cylindrical shells

“…The above gelatin ring experiments help shed light on feedthrough and subsequent growth at the inner surface of single-shell capsules like the ones planned for NIF 8,41 . Another class of capsules involves double-shell designs 8,42 where an inner capsule containing the fuel gas is imploded after colliding with an outer shell. To shed light on the many instabilities that can occur in double-shell capsules we have studied the possibility of double-shell gelatin rings.…”

Ignition and burn of a small magnetized fuel target

“…4 of Varnum, et al, [15]) show that targets with high convergence ratios perform poorly. The target presented here provides high gain with a fairly low convergence ratio.…”

Evolution of surface structure in laser-preheated perturbed materials

“…For hydrodynamic instability of surface perturbations in typical HED systems, this time scale is typically one to a few nanoseconds. A particular example is the double-shell concept for the design of fuel capsules for inertial confinement fusion [16][17][18][19][20]. This scheme, employing two concentric spherical shells, adds considerable complexity to the capsule design, but inclusion of the second capsule may mitigate difficulties arising from issues such as drive asymmetry and convergence.…”

“…This scheme, employing two concentric spherical shells, adds considerable complexity to the capsule design, but inclusion of the second capsule may mitigate difficulties arising from issues such as drive asymmetry and convergence. Experiments exploring double-shell implosions using the indirect-drive approach have been carried out on virtually every generation of major pulsed laser system, starting with Shiva [21,22] and continuing through OMEGA-60 [16,23], and planned work at the NIF [24] is currently under development [20,25]. Double-shell capsules are also a possible option for the direct-drive approach [26][27][28], although preheat in this case behaves differently than with hohlraum indirect drive.…”