Many kinds of laser fusion targets have been used for the laser-target interaction experiments. In this report, we have summarized the fabrication techniques of three types of the targets; (i) gas filled microsphere targets, (ii) parafinic deuterium compound targets and (iii) cryogenic targets. These techniques should be useful to fabricate the high gain targets for the future laser fusion reactors.
Organic insulators, such as polyimide, epoxy resins and fiber reinforced epoxies (FRP), are irradiated in the fission reactor at about 5K and their mechanical properties are measured in liquid helium without warm-up. At the very low temperature, the materials are completely brittle and the serration in the stress-strain curves takes place on polyimide, epoxy resins and CFRP. After irradiation of the absorbed dose of 1.1×109 rad at about 5K, the breaking stress of epoxy resins reduces by 30-40% and FRP and polyimide exhibit a little decrease in the mechanical strength. FRP and polyimide have good radiation resistance on the mechanical behavior after dose of -1×109 rad as compared with other selected organic materials.
The Nb3Sn tape consisting of 27 filaments in a Nb matrix was made by means of the internal diffusion between a 5at.%Cu-Sn alloy and Nb. The Nb3Sn layer could be formed in several hours and was found to have a critic al temperature of 17.6K. Overall current density of 2.0×104A/cm2 at 100kG was obtained for a suitably heat treated sample for which the ratio of Nb3Sn to the composite was below 5%.