Initial Performance of the High-Pressure DT-Filling Portion of the Cryogenic Target Handling System

6 LLE Review, Volume 81 Cryogenic targets for the OMEGA laser are polymer shells of ~1-mm diameter and 1to 5-μm wall thickness that require internal D2 or DT solid layers of ~100-μm thickness. Targets containing D2 may also be doped with gaseous He 3 to aid in diagnosing the implosion using the charged-particle spectrometer. To achieve the required inner ice layer, shells are first permeated to a pressure of ~1000 atm at room temperature and then cooled to ~25 K. A slow, controlled pressure ramp to avoid buckling of the target and a slow, controlled temperature ramp to 25 K are required to successfully fill targets. The thinnest-walled shells, which are of the greatest interest, have buckling pressures 0.1 atm, which imposes a requirement of considerable precision in controlling the pressure differential across the shell wall during the pressurization and cooldown. LLE has constructed a system that successfully fills thickwalled targets and demonstrates the capabilities necessary to fill thin-walled targets. Initial Performance of the High-Pressure DT-Filling Portion of the Cryogenic Target Handling System