Integrated Kinetic Simulation of Laser-Plasma Interactions, Fast-
electron Generation and Transport in Fast Ignition

Andreas Kemp, L.Divol and B.Cohen, LLNL

We present new results on the physics of short-pulse laser-matter
interaction of kilojoule-picosecond pulses at full spatial and
temporal scale, using an approach that combines a 3D collisional
electromagnetic Particle-in-Cell code with an MHD-hybrid model of high-
density plasma. In the latter, collisions damp out plasma waves so the
displacement current can be neglected; and an Ohm's law with electron
inertia effects neglected determines the electric field [Cohen, Kemp,
Divol, J.Comp.Phys. 229 (2010)]. In addition to yielding orders of
magnitude in speed-up while avoiding numerical instabilities, this
allows us to model the whole short pulse laser plasma interaction
problem in a single unified framework: the laser-plasma interaction at
sub-critical densities, energy deposition at relativistic critical
densities, and fast-electron transport in solid densities. We address
key questions such as characterizing the multi-picosecond temporal
evolution of the laser energy conversion into hot electrons, i.e.,
conversion efficiency as well as angular- and energy distribution; the
impact of return currents on the laser-plasma interaction; and the
effect of self-generated electric and magnetic fields on electron
transport. We will report applications to current experiments at
LLNL's Titan laser and Omega EP, and to a Fast-Ignition point design.

This work was performed under the auspices of the U.S. Department of
Energy by Lawrence Livermore National Security, LLC, Lawrence
Livermore National Laboratory under Contract DE-AC52-07NA27344