Events Calendar

Energy Partitioning and Evolution in Collisionless Plasmas: Electron Heating in Shocks

Collin Brown; University of Iowa

We present novel methods for measuring the complex energy-transferring processes of collisionless plasmas that evoke kinetic mechanisms. Previously, determining the energy contributions by kinetic processes has been difficult as isolating individual kinetic mechanisms to determine the isolated energization is non-trivial and requires unique approaches for each class of mechanisms. We apply these methods towards perpendicular supercritical shocks, shocks traveling faster than the critical Mach number and evoking significant energy dissipation through kinetic mechanisms, to gain insight into the energization of non-homogenous and non-linear plasmas. The rapid conversion of supersonic flow energy into thermal energy and particle acceleration in shocks produces difficult-to-predict energy ratios between particle species. Our methods reorganize the plasma energization and energy flux terms to isolate the mechanisms causing the heating of electrons beyond adiabatic predictions. We find that the conversion of parallel to perpendicular electron pressure by wave-particle interaction enhances the energization of the diamagnetic drift by the motional electric field to cause it to heat beyond the typical amount that conserves the second adiabatic invariant. Additionally, we observe significant direct heating by wave-particle interactions via the parallel electric field and the gain of internal energy due to the reflection of electrons localized to the transition region of the shock. Ultimately, these methods are critical for processing in-situ measurements and simulations as they enable the measurement of energy-transferring processes in isolation.