Kinetic simulations of electron pre-energization by magnetized collisionless shocks in expanding laboratory plasmas

Collisionless shocks are common features in space and astrophysical systems where supersonic plasma flows interact. Recently experimental capabilities and diagnostics evolved sufficiently to allow detailed laboratory investigations of high-Mach number shocks [1]. Magnetized collisionless shocks are known to be responsible for the generation of energetic particles due to Fermi process, given enough pre-energization to enter the diffusive acceleration stage. Using 1D and 2D PIC simulations, we investigate particle acceleration mechanisms relevant to laboratory magnetized collisionless shocks. We consider two geometries: two colliding quasi-1D slabs, which can be cross-validated with previous numerical studies, and an ablation model which mimics plasma profiles observed in the expanding plasma experiments. With a parametric scan over shock parameters, we obtain predictions for the magnitude of shock-accelerated electron populations in the upstream and shock layer and their dependence on shock and plasma parameters. Near-future experiments appear capable of reaching these conditions, which will allow laboratory study of particle acceleration by shocks. [1] D.B. Schaeffer et al., Phys. Rev. Lett. 122, 245001 (2019)