Effects of Alpha Particle Fraction on Kinetic Plasma Turbulence

Abstract

Abstract Solar activities have an extraordinary impact on interplanetary space, enriching the plasma dynamics including turbulent heating of various species. The small fraction of alpha particles is believed to play a significant role in the turbulent dynamics of the solar wind. Here we present fully kinetic particle-in-cell simulations to reveal the influences of the alpha particles in decaying plasma turbulence. Multiple run cases with different controlled variations of proton and alpha density are performed to compare and evaluate the energy conversion processes. It is found that the alpha particles can suppress the energy conversion rate with increasing density. Besides, the alpha particles show more heating intermittency than the proton species. Interestingly, on the other hand, the electrons do not show any change in their dynamics, including overall heating. These two positive charge species have more correlation in temperature anisotropy as their densities are comparable. Our results provide valuable insights on the turbulence with different species compositions to a certain extent, especially with abundant heavy particles.