The Division of Energy Between Ion Subpopulations in Collisionless Supercritical Quasiperpendicular Shocks

In collisionless shocks that exceed the first critical Mach number, you see a splitting of incoming particles at the shock interface between transmitted particles that are decelerated by the cross shock electric field and reflected particles which are accelerated through shock-drift acceleration (SDA). Through a series of quasiperpendicular shock simulations, generated with the parallel hybrid code dHybridR and spanning different upstream Mach number and shock-normal angle, we seek to identify how energy within a shock is partitioned between the transmitted and reflected/accelerated ion populations. We do so by defining volumes in velocity space which separate the transmitted and reflected ions. Using these volumes in conjunction with the distribution function and field-particle correlation allows for the energy flux to be calculated for these ion populations separately. Looking at the ion energy flux for the reflected ions, and what fraction of total energy flux they comprise in particular, gives a measure of how prominent a role SDA plays within a given shock. By looking at how this quantity varies across different shock parameters and identifying an expression to model this variation, we can determine the dependence of SDA and the nonthermal acceleration of ions on these different parameters.