Fabrication and Characterization of Targets for Shock Propagation and Radiation Burnthrough Measurements on Be-0.9 AT. % Cu Alloy

Beryllium-copper alloy (Be0.9%Cu) ICF capsules are being developed for the pursuit of thermonuclear ignition at the National Ignition Facility (NIF). Success of this capsule material requires that its shock propagation and radiation burnthrough characteristics be accurately understood. To this end, experiments are being conducted to measure the shock propagation and radiation burnthrough properties of Be0.9%Cu alloy. These experiments involve measurements on small Be0.9%Cu wedge, step and flat samples. Samples are mounted on 1.6-mm-diameter × 1.2-mm-length hohlraums that are illuminated by the OMEGA laser at the University of Rochester. X-rays produced by the hohlraum drive the sample. A streaked optical pyrometer detects breakout of the shock produced by the X-ray pulse. In this paper we describe synthesis of the alloy material, fabrication and characterization of samples, and assembly of the targets. Samples were produced from Be0.9%Cu alloy that was synthesized by hot isostatic pressing of Be powder and copper flake. Samples were 850 m diameter disks with varying thickness in the case of wedge and step samples, and uniform thickness in the case of flat samples. Sample thickness varied in the range 10-90 m. Samples were prepared by precision lathe machining and electric discharge machining. The samples were characterized by a Veeco white light interferometer and an optical thickness measurement device that simultaneously measured the upper and lower surface contours of samples using two confocal laser probes. Several campaigns with these samples have been conducted over the past two years.