Department of Mechanical Engineering

Laser-plasma interactions and hot electron generation in shock ignition and Adapting a collision package in particle-in-cell simulations on GPU

Rui Yan and Jun Li

Hopeman 224

Part 1-presented by Rui Yan-

We present particle-in-cell (PIC) simulations for laser-plasma interactions in the recent 40+20-beam spherical shock ignition experiments on the Omega laser facility. Two-dimensional PIC simulations including electron-ion collisions and lasting more than 10 ps show a bursting pattern in both plasma waves and hot electron fluxes, which are attributed to the interplay between stimulated Raman scattering (SRS) and two-plasmon decay (TPD) instabilities. SRS is the main source for hot electrons but TPD can produce >100 keV ones. The observed hot electron temperatures compare favorably to those measured in the experiments.
* This work was supported by the U.S. Department of Energy under under Grant No. DE-FC02-04ER54789 and Cooperate Agreement No. DE-FC52- 08NA28302, by NSF under Grant No. PHY-0903797, and by NSFC under Grant No. 11129503. The research used resources of NERSC.

Part 2-presented by Jun Li-

A collision package is developed for a PIC (particle-in-cell) code on parallel graphics processors (GPU) with CUDA [X. Kong et al, J. Com. Phys, 230, 1676 (2011)]. The collision package is based on the cumulative collision theory [K. Nanbu, Phys.Rev.E, 55, 4642 (1997)]. It uses the sorting cell (or cluster) in the GPU-PIC code as the collision cell. The benchmarks on Dirac and Hoffman2 show that this collision package has a performance of 0.07~0.09 ns/particle/step, only a 1.4% increase to the performance of ~5 ns/particle/step without collisions. Test problems of beam-plasma scattering and electron plasma wave damping show that the collision frequencies calculated from the simulation results are consistent with theory. This work was supported by NNSA under Corporate Agreement No. DE-FC52-08NA28302; by DOE under Grant No. DE-FC02-04ER54789; by NSF under Grant No. PHY-0903797; and by NSCF under Grant No. 11129503. (Collaboration with M. C. Huang, ECE UR and W. B. Mori, UCLA)