The design, fabrication and testing of beryllium capsules for resonant ultrasound experiments

Inertial Confinement Fusion (ICF) ignition targets require smooth and well- characterized deuterium/tritium (DT) ice layers. Los Alamos is developing R esonant Ultrasound Spectroscopy(1) (RUS) to measure the internal pressure i n the targets at room temperature after filling with DT. RUS techniques als o can detect and measure the amplitudes of low modal surface roughness pert urbations of the target shell interior. The experiments required beryllium capsules with a nominal inside radius of 1 mm and a spherical outside radius of 3 mm. The capsules have various sph erical harmonic contours up to mode 12 machined into their interior surface s. The capsules are constructed from hemispheres using an epoxy adhesive(2) and then filled to similar to 270 atm with helium or deuterium gas. This paper describes the adhesive joint design, machining techniques, and i nterior geometry inspection techniques. It also describes the fixtures need ed to assemble, fill, and pressure test the capsules.