Preliminary Results of Fuel Layering on the Cryogenic Target for the FIREX Project

The fuel layering process of a cryogenic target for the Fast Ignition Realization EXperiment (FIREX) project has been studied. A foam shell method is proposed as a fuel layering technique for this target design. The difficulty of the fuel layering comes from the aspherical target symmetry. In the case of the foam shell method, liquid fuel is directly infiltrated into a foam shell though a fuel feeder and is soaked up into the foam layer by capillarity. The fuel is then solidified and an ideal cryogenic target is formed. To date, the cryogenic system for the demonstration of the fuel layering was fabricated and subsequently modified to improve its cool-down performance. A dummy foam target has been utilized to study the fuel layering process using H₂ instead of D₂ and DT fuels. Liquid H₂ is supplied into the shell through a feeder with a 20 m inner tip diameter. The solid H₂ quantity remaining in the shell was controlled by regulating both H₂ pressure and target temperature during solidification.