Parametric Decay Instability and Dissipation of Low-frequency Alfv\'en Waves in Low-beta Turbulent Plasmas

TL;DR

This study uses 3D hybrid simulations to explore how parametric decay instability (PDI) of Alfvén waves behaves in turbulent low-beta plasmas, revealing reduced growth and damping rates but significant ion heating, highlighting a new energy dissipation channel.

Contribution

It demonstrates that PDI persists in turbulent low-beta plasmas with altered growth and damping rates, providing a novel energy dissipation mechanism at large scales.

Findings

Turbulence reduces PDI growth rate compared to linear theory.

Ion acoustic wave damping rate is lower than Vlasov predictions.

Significant ion heating occurs via Landau damping of ion acoustic waves.

Abstract

Evolution of the parametric decay instability (PDI) of a circularly polarized Aflv\'en wave in a turbulent low-beta plasma background is investigated using 3D hybrid simulations. It is shown that the turbulence reduces the growth rate of PDI as compared to the linear theory predictions, but PDI can still exist. Interestingly, the damping rate of ion acoustic mode (as the product of PDI) is also reduced as compared to the linear Vlasov predictions. Nonetheless, significant heating of ions in the direction parallel to the background magnetic field is observed due to resonant Landau damping of the ion acoustic waves. In low-beta turbulent plasmas, PDI can provide an important channel for energy dissipation of low-frequency Alfv\'en waves at a scale much larger than the ion kinetic scales, different from the traditional turbulence dissipation models.