Flux-tube-dependent propagation of Alfv\'en waves in the solar corona

TL;DR

This study investigates how Alfvén waves propagate and evolve in the solar corona, highlighting the influence of flux-tube geometry and wave reflection on turbulent heating and solar wind acceleration.

Contribution

It introduces a flux-tube-dependent model of Alfvén wave propagation in the solar corona using ideal MHD simulations, emphasizing the effects of flux-tube geometry and wave reflection.

Findings

Alfvén waves are reflected due to parametric decay instability.

Reflection efficiency depends on wave frequency and flux-tube geometry.

Parametric decay instability is suppressed by low-frequency reflections and flux-tube structure.

Abstract

Alfv\'en-wave turbulence has emerged as an important heating mechanism to accelerate the solar wind. The generation of this turbulent heating is dependent on the presence and subsequent interaction of counter-propagating alfv\'en waves. This requires us to understand the propagation and evolution of alfv\'en waves in the solar wind in order to develop an understanding of the relationship between turbulent heating and solar-wind parameters. We aim to study the response of the solar wind upon injecting monochromatic single-frequency alfv\'en waves at the base of the corona for various magnetic flux-tube geometries. We used an ideal magnetohydrodynamic (MHD) model using an adiabatic equation of state. An Alfv\'en pump wave was injected into the quiet solar wind by perturbing the transverse magnetic field and velocity components. Alfv\'en waves were found to be reflected due to the development of the parametric decay instability (PDI). Further investigation revealed that the PDI was suppressed both by efficient reflections at low frequencies as well as magnetic flux-tube geometries.