Barry L. Barthell

Unbacked cylindrical metal foils of submicron thickness

Abstract Implosion experiments often utilize cylindrical thin metal foils. Previously these foils have been made either from flat sheets, with a seam where the edges joined, or in the form of a composite polymer/metal laminate, in which the plastic film acts as a supporting substrate. A method has been developed to produce unbacked cylindrical metal foils of submicron thicknesses. This process utilizes a temporary substrate consisting of a water-soluble polymer film as a base for the electron beam deposition of the metal layer. After formation of the metal foil, the polymer is removed by immersion of the assembly in water. Unbacked metal foil cylinders as thin as 0.17 μm with extremely smooth wrinkle-free surfaces have been produced by this technique.

Coating techniques used in target fabrication

Abstract A review of coating techniques used to fabricate targets and experimental components is presented. Coating techniques include physical vapor deposition, chemical vapor deposition, electroplating and dip coating. In all cases the substrate or mandrel material is removed from the coating to result in the final part.

Vacuum deposition of high quality metal films on porous substrates

A composite mandrel has been developed consisting of a core of low density polymethylpentene foam overcoated with a thin layer of film‐forming polymer. The surface tension and viscosity of the coating solution are important parameters in obtaining a polymer film which forms a continuous, smooth skin over the core without penetrating into the foam matrix. Water soluble film formers with surface tensions in the range of 45 dyn/cm and minimum viscosities of a few hundred centipoises have been found most satisfactory for coating polymethylpentene foam. By means of this technique, continuous polymer fims with thicknesses of 10–20 μm have been formed on the surface of machined polymethylpentene foam blanks. Aluminum has been vacuum deposited onto these composite mandrels to produce metal films which appear smooth and generally defect free even at 10 000 times magnification.

High‐Z elements in laser fusion targets

Recent laser fusion experiments conducted by Los Alamos physicists have required the use of high‐Z elements in atypical applications. Gold, a commonly used element, has been deposited in low‐density smoke form onto plastic and glass spheres. Thorium and uranium have been requested as x‐ray backlighter materials, and wires etched to <10 μm have been produced for this purpose. Uranium has also been vapor deposited onto spheres and 7–10 μm fibers with varying degrees of success.

Pinhole plate diagnostic for neutral particle beam accelerator

Abstract An unusual method of forming a foil with highly accurate hole placements and overlayed stripper/neutralizer foil allows accurate beam divergence and density diagnostics when used in conjunction with a downstream fluorescent screen and high resolution photography.

Surface modification of polymeric materials and its effect on blood compatibility

The surfaces of commercially available polymeric materials have been modified through the chemical infusion process and physical vapor deposition. The surfaces of poly(methylmethacrylate) (PMMA) have been modified through a chemical infusion process by treatment of the sample with a solution containing varying amounts of titanium(IV)isopropoxide and polyvinylpyrrolidone (PVP). The surfaces of silicone rubber samples have been coated with a thin coating of titanium dioxide with an ion beam sputtering technique. The treated samples were characterized by scanning electron microscopy, optical microscopy, and neutron activation analysis. The infused samples were evaluated for blood compatibility using two biological assays: an adherence assay in which the adherence of human polymorphonuclear leukocytes to the samples was determined, and a hemolysis assay using rat blood erythrocytes to determine the hemolytic activity of the samples. Based on the results of these assays, the PMMA samples treated with PVP alone resulted in an improvement in reactivity with the blood cells. 16 refs., 4 figs.