Recent OSIRIS development for improved high-energy- density plasma simulations

OSIRIS is a parallelized, fully relativistic, explicit particle-in-cell code. Some studies of nonlinear optics of plasmas are very sensitive to noise and numerical instabilities. OSIRIS uses charge conserving current deposit to maintain Gauss’s law but recent implementation of a Boris correction (including a multigrid Poisson solver) combined with a direct current deposit provides a low-noise alternative. In addition, the Boris correction may allow for the use of higher-order stencils in the field solver to limit the numerical Cerenkov instability. Preliminary results comparing these options for SRS and the Weibel instability will be presented. Finally, performance on both a future single many core node and on large parallel simulations can be improved by partitioning data into small units known as tiles. This provides the ability to stream particle operations and provides flexibility needed to implement load-balancing schemes which may improve the parallel scalability of problems such as laser wakefield and laser-solid interactions. Details for this implementation into the non-CUDA version of OSIRIS 4.0 as well as preliminary timings of OSIRIS on the Intel Xeon Phi with and without tiling will be presented.