  We describe how a new framework for coupling a full-PIC algorithm with a
reduced PIC algorithm has been implemented into the code OSIRIS. We show that
OSIRIS with this new hybrid-PIC algorithm can efficiently and accurately model
high energy density scenarios such as ion acceleration in laser-solid
interactions and fast ignition of fusion targets. We model for the first time
the full density range of a fast ignition target in a fully self-consistent
hybrid-PIC simulation, illustrating the possibility of stopping the laser
generated electron flux at the core region with relatively high efficiencies.
Computational speedups greater than 1000 times are demonstrated, opening the
way for full-scale multi-dimensional modeling of high energy density scenarios
and for the guiding of future experiments.
