Plasma turbulence is ubiquitous in space and astrophysical environments across a wide range of scales and plays an essential role in plasma dynamics. In particular, in high-energy astrophysical systems such as black-hole accretion flows, turbulent dissipation is thought to be responsible for heating both ions and electrons. However, because ions radiate much less efficiently than electrons, their temperature is difficult to constrain directly from observations. Numerical simulations therefore provide an important means of understanding how turbulent energy is partitioned between ions and electrons.

The ion heating rate depends strongly on the properties of the turbulence. One particularly important property is the imbalance between counter-propagating Alfvénic fluctuations. Imbalanced turbulence is observed, for example, in the solar corona. In sufficiently imbalanced turbulence, a phenomenon known as the helicity barrier can arise, potentially leading to enhanced ion heating by suppressing the forward cascade of generalized helicity and altering the transfer of turbulent energy at kinetic scales.

In this study, we perform particle-in-cell (PIC) simulations of imbalanced turbulence in an ion–electron plasma to investigate how turbulence and plasma heating change with increasing imbalance. Unlike previous studies, which typically drive turbulence using prescribed Alfvénic fluctuations, we drive the system through external acceleration and magnetic-field forcing. This approach allows us to achieve an unprecedentedly high degree of imbalance in PIC simulations. Nevertheless, we find that a helicity barrier does not develop; instead, electrons are preferentially heated. In this seminar, I will discuss the behavior of highly imbalanced kinetic turbulence, the resulting partition of turbulent heating between ions and electrons, and possible reasons why the helicity barrier does not emerge in our simulations.