Heavy-ion direct-drive T-lean targets for self-T breeding and plasma MHD direct conversion

Transverse and longitudinal beam compression in neutralizing plasma enable heavy ion beam direct drive in the ablative rocket regime at high rocket efficiency with ion ranges a fraction of the initial ablator thickness for low adiabat implosions. Ions can couple energy into thick fuel capsule ablators at the peak in rocket efficiency as efficiently as x-rays do in hohlraums, but without conversion loss of beam energy into x-rays. High ablation velocities with heavy ion direct drive mitigate hydrodynamic instabilities like x-ray drive. An analytic implosion model with a heavy-ion dE/dx deposition model, together with hydrodynamic implosion calculations (LASNEX and HYDRA) explore beam requirements for heavy ion direct drive for small 1 MJ drive DT targets and larger Tritium-lean ($>$ 90{\%} DD) targets. Both model and implosion codes indicate ion beams can couple $>$15{\%} of their incident energy into compressed fuel assemblies. Increasing ion energy during the drive pulse can reduce the parasitic beam losses on ablated plasma.