Extensions of the magnetic pumping model for particle heating*

One of the outstanding problems across a variety of astrophysical phenomena is the generation of electron and ion power-law distributions with superthermal tails. Most theories of particle energization rely on energy injection at a specific scale, such as the energy injection at the kinetic scale after passing through the turbulent cascade. We have shown that magnetic pumping, a model in which particles are heated by the largest scale magnetic fluctuations, is a complementary heating mechanism to the turbulent cascade, resulting in power-law distributions like those observed in the solar wind [1]. The ability of compressional Alfv\'enic turbulence to magnetically trap superthermal particles renders magnetic pumping an effective Fermi heating process for particles with $v\gg \omega/k$, and produces superthermal power-law distributions. Recent progress and extensions of this model will be presented, including the application of this model to differential ion heating near the solar corona. [1] E. Lichko, J. Egedal, W. Daughton, and J. Kasper. \textit{Astrophys. J. Lett.} \textbf{2}, 850 (2017)