Density-gradient-driven drift-wave turbulence in the solar corona

AAM Embargoed until 2025-10-24, The solar corona is a highly filamentary environment with density gradients of diverse scales and strengths. If perpendicular to the background magnetic field, such gradients give rise to drift waves (DWs) via the drift wave instability, leading to plasma heating and particle, heat and momentum transport. Particularly in the context of the coronal heating and solar wind acceleration problems, it is instructive to study DWs to determine how they may affect the budgets of the coronal plasma. This paper investigates densitygradient- driven DWs in the solar corona using nonlinear gyrokinetic simulations, particularly fluctuation frequencies and coronal heating. Methods.We use the gyrokinetic code Gene to simulate DWturbulence in slab geometry, representing a coronal loop. Simulations are carried out at hydrogen mass ratio for cases with varying magnetic shear, density gradient scale lengths and electron β, each covering ranges relevant to the corona. Results. Frequencies between 0.1 mHz up to a few Hz are obtained, with larger values possible for hotter and smaller structures. Turbulence spectra exhibit tails consistent with kinetic Alfvén wave turbulence. Particle acceleration in the parallel direction occurs, although this process may account for observed volumetric heating rates only in regions with high gradients. In the perpendicular direction, conditions are generally such that fast stochastic heating can occur. Finally, the structure erosion timescales indicate that while DW turbulence may flatten gradients over time, most structures are expected to survive for days without additional driving. Conclusions. Drift waves are expected to be unstable in the solar corona and can, especially when arising from strong density gradients, create an environment suitable for particle acceleration and plasma heating both parallel and perpendicular to the magnetic field on the timescales of hours up to days. Future modelling will assess DW behaviour in stronger gradients and in more complex configurations.