Gerald Martin Halpern

Laser fusion microballoon wall‐thickness measurements: A comparative study

A comprehensive study of the measurement of the wall thickness of microballoons for laser‐induced fusion has been completed. Four different techniques have been investigated: microradiography, scanning electron microscopy, and two interference methods. Measurements of wall thickness on 13 microballoons have been made by all techniques. The results obtained with the four methods were equal within the experimental error of each.

Deuterated polyethylene microspheres of variable density for laser‐fusion targets

This paper describes the experimental procedure we have developed for producing spherical deuterated polyethylene targets with a continuum of densities in the range 20–60% that of solid (ρsolid?1.0 g/cm3). These spheres (termed ’’microsponges’’) are typically 80–300 μm in diameter and are highly porous networks with average pore sizes of a few microns or smaller. The technique consists of (i) forming solid (i.e., normal density) microspheres by pulverizing and spheroidizing the (CD2)n starting material, (ii) cross linking the polyethylene chains in a γ‐ray flux, (iii) swelling the cross‐linked network in an appropriate hot solvent such as p‐xylene, and (iv) rapidly extracting the solvent to ’’freeze‐in’’ the expanded structure in the final target. A quantitative model based upon the theory of swollen networks has been employed to correlate the measured densities with the experimental parameters, such as radiation dosage, solvent type, and swelling temperature.

DISCUSSION OF ''TWO-STREAM INSTABILITY IN PLASMA.''

Two stream instabilities in inhomogeneous two fluid plasma as simply growing transverse oscillations stimulated by external radiation sources