FABRICATION OF CYLINDRICAL, MICROCELLULAR FOAM-FILLED TARGETS, CONTAINING ALUMINUM SPHERES, FOR SPHERE DRAG EXPERIMENTS

Hollow cylindrical fusion targets of 200–300 μm diam and 500–600 μm length, were fabricated and fitted at one end with a metallic ablator plate. The cylinders were then filled with a solution of polyfunctional acrylate monomer, which was subsequently polymerized to a gel using ultraviolet initiated polymerization. Either one or two aluminum spheres of diameter between 10 and 30 μm were placed in the gel at defined locations, before the gel was precipitated to give, on drying by critical point dryer, a foam of the required density (about 100 mg cm−3). The final targets had the sphere or spheres embedded in the foam at specified locations. Several techniques for placing the spheres were examined and the relative merits of the techniques are discussed.