Key Physics Issues in Target Design for Heavy-Ion Fusion

Recent progress on a few key physics issues for the design of indirect-drive targets for heavy-ion fusion is reviewed. The critical dependence of the gain predictions on such issues as symmetry, stability, and radiation generation is illustrated by means of a model for the target gain. Design constraints set by the Rayleigh-Taylor instability are discussed. Then, beam-to-capsule energy coupling in hohlraums with a few converters is considered, with emphasis on radiation generation and symmetrization. Results are also given on an alternate, spherically symmetric indirect-drive target, with a diffuse converter; the conditions for effective radiation drive and hydrodynamic insulation are discussed.