Fabrication and characterization of planar cryogenic targets for GEKKO-XII

Abstract

A planar cryogenic target system was built to simulate the ablator+fuel shell physics in ICF experimental studies. In the center of the target cell, a sandwich target of liquid deuterium was formed, which has open geometry for conventional side-on and face-on backlighting diagnostics. A set of double-flanges comprised a sealing flange and an extra flange, with which the target thickness could be changed using proper spacers. Furthermore, an interferometric method was used to characterize the cryogenic target before laser shot. The in situ target thickness and bulging shape could be obtained with acceptable accuracy. A typical planar cryogenic target was formed with diameter of 2 mm, which comprised three parts: a 7-μm thick polyimide film, a layer of liquid deuterium with the thickness of 119 μm at the center and 100 μm at the edge, and another 7-μm thick polyimide film.