Two-fluid 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. Based on Magnetohydrodynamic (MHD) theories, the leading candidate is reflection from an Alfven speed gradient in the corona. However, prior experimental tests of Alfven wave reflection from a magnetic field gradient in the LArge Plasma Device (LAPD) at UCLA do not agree with the MHD reflection predictions, possibly due to physics beyond MHD. In this talk, we present the Gkeyll simulation framework as general use tool to model LAPD. In this case, we use the Gkeyll two-fluid solvers to explore the role physics beyond MHD may play in the reflection of Alfven waves. We compare Gkeyll simulations to previous LAPD experiments for which reflection was not observed, and we present recent LAPD experiments that do exhibit reflection. In both cases, we find that two-fluid physics well models Alfven wave reflectance in LAPD experiments.