Modelling Fast-Alfv\'en Mode Conversion Using SPARC

TL;DR

This paper demonstrates the use of the SPARC code to model fast-Alfvén mode conversion in helioseismic waves through 3D MHD simulations, highlighting the importance of background stratification modifications over Lorentz Force limiters.

Contribution

It introduces a novel approach to simulate fast-Alfvén mode conversion by empirically adjusting background stratifications instead of using Lorentz Force limiters.

Findings

Lorentz Force limiters inhibit mode conversion.

Empirical stratification modifications enable realistic simulations.

Mode conversion is sensitive to magnetic flux damping.

Abstract

We successfully utilise the SPARC code to model fast-Alfv\'en mode conversion in the region $c_A \gg c_S$ via 3-D MHD numerical simulations of helioseismic waves within constant inclined magnetic field configurations. This was achieved only after empirically modifying the background density and gravitational stratifications in the upper layers of our computational box, as opposed to imposing a traditional Lorentz Force limiter, to ensure a manageable timestep. We found that the latter approach inhibits the fast-Alfv\'en mode conversion process by severely damping the magnetic flux above the surface.