Computational design of high efficiency release targets for use at ISOL facilities

摘要

This paper describes efforts made at the Oak Ridge National Laboratory to design high-efficiency-release targets that simultaneously inorporate the short diffusion lengths, high permeabilities, controllable temperatures, and that removal properties requjired for the generation of useful radioactive ion beam (RIB) intensities for nuclear physics and astrophysics research using the isotope separation on-line (ISOL) technique. Short diffusion lengths are achieved either by using thin fibrous target materials or by coating thin layers of selected target material onto low-density carbon fibers such as reticulated vitreous carbon fiber (RVCF) or carbon-bonded-carbon-fiber (CBCF) to form highly permeable com[osite target matrices. Computational studies which simulate the generation and removal of primary beam deposited heat from target materials have been conducted to optimize the design of target/heat-sink systems for generating RIBs. The results derived from diffusion release-rate simulation studies for selected targets and thermal analyses of temperature distributions within a prototype target-heat-sink system subjected to primary ion beam irradiation will be presented in this report.