  An indirect-direct hybrid-drive work-dominated hotspot ignition scheme for
inertial confinement fusion is proposed: a layered fuel capsule inside a
spherical hohlraum with an octahedral symmetry is compressed first by
indirect-drive soft-x rays (radiation) and then by direct-drive lasers in last
pulse duration. In this scheme, an enhanced shock and a follow-up compression
wave for ignition with pressure far greater than the radiation ablation
pressure are driven by the direct-drive lasers, and provide large pdV work to
the hotspot to perform the work-dominated ignition. The numerical simulations
show that the enhanced shock stops the reflections of indirect-drive shock at
the main fuel-hotspot interface, and therefore significantly suppresses the
hydrodynamic instabilities and asymmetry. Based on the indirect-drive implosion
dynamics the hotspot is further compressed and heated by the enhanced shock and
follow-up compression wave, resulting in the work-dominated hotspot ignition
and burn with a maximal implosion velocity of ~400 km/s and a lower convergence
ratio of ~25. The fusion yield of 15 MJ using total laser energy of 1.32 MJ is
achieved.
