Fully Exploiting 3D-3V Phase Space to Understand Plasma Heating and Particle Acceleration in Collisionless Shocks

In weakly collisional plasmas, the physical mechanisms by which the plasma species are heated and particles are accelerated are governed by collisionless interactions between the electromagnetic fields and individual particles. The recently developed field-particle correlation technique was devised to identify and characterize the mechanisms that energize particles in the six-dimensional (3D-3V) phase space of kinetic plasmas, mechanisms underlying the fundamental plasma processes of kinetic turbulence, collisionless magnetic reconnection, and collisionless shocks. Here we present an overview of how the field-particle correlation method can be applied to gain deeper insight into the kinetic plasma processes that govern how particles are energized at collisionless shocks. Requiring only single-point measurements in space, the technique can be used to identify well-known acceleration mechanisms, such as shock drift acceleration and shock surfing acceleration. In addition, it shows promise to be able to separate the energization mediated by micro-instabilities arising in the shock transition from that due to the macroscopic shock fields.