Fabrication of high-gain inertial fusion targets using gas jet cooling and intensity-graded laser illumination

A new method, which is particularly suitable for fabricating a uniformly thick solid- or liquid-fuel layer inside an inertial confinement fusion target, is described. The method employs a cold helium-gas-jet shower to uniformly cool a target and an intensity-graded laser illumination to create a desired thermal gradient across the target. The net result is a thermally induced fuel migration inside the target, which precisely counterbalances the gravity-induced fuel sagging, bringing about a uniform layer of fuel condensate on the target interior. This new method is significant for the following reasons: First, it allows for fabrication of both solid- and liquid-fuel layers. Second, it is a noncontact method. Third, it requires either none or very little cryogenic shielding. Fourth, it is simple to implement. Fifth, it allows for easy diagnostic access to the target. Details of the apparatus and results showing the capabilities of the method are presented.