Advanced fuel layering in line-moving, high-gain direct-drive cryogenic targets

In inertial fusion energy (IFE) research, a number of technological issues have focused on the ability to inexpensively fabricate large quantities of free-standing targets (FSTs) by developing a specialized layering module with repeatable operation. Of central importance for the progress towards plasma generation with intense thermonuclear reactions is the fuel structure, which must be isotropic to ensure that fusion will take place. In this report, the results of modeling the FST layering time, tau(Form), are presented for targets which are shells of similar to 4 mm in diameter with a wall made from compact and porous polymers. The layer thickness is similar to 200 mu m m for pure solid fuel and similar to 250 mu m m for in-porous solid fuel. Computation shows tau(Form) < 23 s for D-2 fuel and tau(Form) < 30 s for D-T fuel. This is an excellent result in terms of minimizing the tritium inventory, producing IFE targets in massive numbers (similar to 1 million each day) and obtaining the fuel as isotropic ultrafine layers. It is shown experimentally that such small layering time can be realized by the FST layering method in line-moving, high-gain direct-drive cryogenic targets using n-fold-spiral layering channels at n = 2, 3.