Symmetry and stability issues in target design for heavy ion fusion

Results on several topics concerning the symmetry and the stability of the implosion of heavy ion inertial confinement fusion (ICF) targets are reported. The Rayleigh-Taylor instability of some direct drive targets, during inward acceleration, is studied by means of 2-D radiation hydrodynamics simulations; it turns out to be unavoidable. Radiation generation, confinement and symmetrization in some hohlraum targets for indirect drive ICF, including cylindrical radiation converters, is studied by 2-D and 3-D codes. It appears that at least six converters are needed to provide adequate radiation symmetrization and efficient radiation coupling to the fusion capsule. Preliminary results of studying a new concept or radiation driven target, including a spherically symmetric converter, are presented. In the final section some results are given on high resolution 2-D studies of the turbulent mixing induced by Rayleigh-Taylor instability. (author). 10 refs, 3 figs