S. F. Martins1, R. A. Fonseca1,2, W. B. Mori3, L. O. Silva1
1Instituto de Plasmas e Fusão Nuclear - Instituto Superior Técnico, Lisbon, Portugal
2DCTI/ISCTE, Lisbon, Portugal
3University of California Los Angeles, Los Angeles, USA
We describe the current state-of-the-art tools available for full particle-in-cell simulations, and detail the specific advantages for modeling of astrophysical scenarios. These tools, currently available in OSIRIS 2.0 [R. A. Fonseca et al, LNCS 2329, III-342 (2002)], involve higher precision field solvers, advanced current and field smoothing, dynamic load balancing for higher parallel efficiency, new hardware features, among others. Results are then presented for ab-initio PIC simulations of relativistic collisionless shocks in electron-ion unmagnetized plasmas. Particle tracking is used to analyze in detail the particle dynamics and the acceleration process. We observe an energy growth in time that can be reproduced by a Fermi-like mechanism with a reduced number of scatterings, in which the time between collisions increases as the particle gains energy, and the average acceleration efficiency is not ideal. The undergoing work on non-relativistic shocks is also addressed, and the main challenges depicted. Finally, a new scheme to generate relativistic fireballs in the laboratory is introduced, with details on the magnetic field generation from the Weibel instability, and the dependence of the physical processes on the initial parameters of the plasma beam and plasma.
Author entry (protected)