Detailed characterization of laboratory magnetized super-critical\n collisionless shock and of the associated proton energization

Abstract

Collisionless shocks are ubiquitous in the Universe and are held responsible\nfor the production of non-thermal particles and high-energy radiation. In the\nabsence of particle collisions in the system, theoretical works show that the\ninteraction of an expanding plasma with a pre-existing electromagnetic\nstructure (as in our case) is able to induce energy dissipation and allow for\nshock formation. Shock formation can alternatively take place when two plasmas\ninteract, through microscopic instabilities inducing electromagnetic fields\nwhich are able in turn to mediate energy dissipation and shock formation. Using\nour platform where we couple a fast-expanding plasma induced by high-power\nlasers (JLF/Titan at LLNL and LULI2000) with high-strength magnetic fields, we\nhave investigated the generation of magnetized collisionless shock and the\nassociated particle energization. We have characterized the shock to be\ncollisionless and super-critical. We report here on measurements of the plasma\ndensity, temperature, the electromagnetic field structures, and particle\nenergization in the experiments, under various conditions of ambient plasma and\nB-field. We have also modeled the formation of the shocks using macroscopic\nhydrodynamic simulations and the associated particle acceleration using kinetic\nparticle-in-cell simulations. As a companion paper of\n\\citet{yao2020laboratory}, here we show additional results of the experiments\nand simulations, providing more information to reproduce them and demonstrating\nthe robustness of our interpreted proton energization mechanism to be shock\nsurfing acceleration.\n