WO21.3 Direct Drive Reentrant Cone Targets for Fast Ignition

摘要

Targets designed for fast ignition must have clear access for the ignitor laser to the compressed core. This is provided in current concepts by embedding a reentrant cone in the shell, the tip of the cone close to the center of the shell. We have designed a gas-tight direct-drive FI target as the first step in developing a FI ignition target, and have studied its implosion dynamics at Omega with back-lit and self-emission framing cameras. A step in the cone surface, and Al on the shell was required to make the assembly gas-tight; these assemblies withstood greater than 10 atm and had a typical pressure half-life of 2-6 hrs. The implosion of these targets was substantially different from that of previous indirect drive targets; there was much less vaporization of the Au cone, much clearer structure in the collapsing shells, and a possibility that the hot core could escape around the cone rather than punch in its tip.