Preliminary experiments on hohlraum-driven double-shell implosion at the ShenGuang-III laser facility

Abstract

Double-shell implosion is proposed as a non-cryogenic target design for ignition, offering a robust implosion platform for inertial confinement fusion research. Hohlraum-driven double-shell implosions have been performed at the ShenGuang-III laser facility; a vacuum hohlraum with a high CCR value was employed. With 96kJ laser energy in a squared temporal profile, the implosion neutron yield was close to 1010, and the YOC1D was about 27%. A fuel areal density of 14 mg cm−2 was inferred from the measured yield ratio of secondary and primary neutrons. The implosion trajectory was diagnosed via the 4.75 keV x-ray backlight. The measured implosion velocity and hot-spot x-ray emission history indicate a predictable hydrodynamic process in the double-shell implosion. Two crucial factors which might detrimentally affect implosion performance are the implosion symmetry and pusher–gas mix. The loss of four driven laser beams in the backlight shot caused the YOC1D to decrease to 5% and fuel areal density to decrease to 4 mg cm−2. In future, optimization of the implosion symmetry and the capsule fabrication will be implemented to improve the double-shell implosion performance.

The influence of driven asymmetry on yield degradation in shaped-pulse indirect-drive implosion experiments at the 100 kJ laser facility

“…In this campaign, all 48 laser beams were injected into the cylindrical hohlraum. The configurations of the laser beams are shown in figure 2(a) (the layout was simulated by the IRAD3D program [61][62][63]). The laser beams were arranged with four cone angles with respect to the hohlrum axis: 8 beams at 28.5 • , 8 beams at 35 • , 16 beams at 49.5 • and 16 beams at 55 • .…”