Reduced Kinetic Gkeyll Simulations of Alfven Wave Reflection From an Alfven Speed Gradient in LAPD

The heating of the solar corona and acceleration of the solar wind is likely driven by Alfvenic turbulence, which requires counter-propagating Alfvenic fluctuations. Alfven waves are observed to be driven from the base of the corona, but the source of inward propagating waves is not yet established. The leading candidate is reflection from an Alfven speed gradient in the solar atmosphere, and recent experiments on the LArge Plasma Device (LAPD) at UCLA have for the first time observed such gradient driven Alfven wave reflection [Bose et al ApJ 2024]. The reflection was also successfully modeled in two-fluid simulations using the Gkeyll simulation framework, finding good qualitative agreement with the experimental data. However, the two-fluid simulations are unable to capture electron Landau damping and collisional damping, both of which are important in LAPD and in the solar atmosphere. In this presentation, we employ a novel reduced kinetic model with Gkeyll called the parallel-kinetic-perpendicular-moment (PKPM) model to study Alfven wave reflection from an Alfven speed gradient in a system that includes all forms of damping, collisionless and collisional, that occur in LAPD and the solar atmosphere.