Alfv\'enic waves in the inhomogeneous solar atmosphere

TL;DR

This paper reviews how inhomogeneities in the solar atmosphere, both along and across magnetic fields, influence Alfvénic wave propagation, revealing complex physics like resonances, turbulence, and instabilities.

Contribution

It provides a comprehensive overview of recent insights into the effects of plasma inhomogeneity on Alfvénic waves in the solar atmosphere.

Findings

Inhomogeneity alters wave modes and propagation characteristics.

Resonances, turbulence, and instabilities are enabled by inhomogeneity.

Understanding wave behavior aids in solar atmospheric energy transfer.

Abstract

The solar atmosphere is known to be replete with magneto-hydrodynamic wave modes, and there has been significant investment in understanding how these waves propagate through the Sun's atmopshere and deposit their energy into the plasma. The waves' journey is made interesting by the vertical variation in plasma quantities that define the solar atmosphere. In addition to this large-scale inhomogeneity, a wealth of fine-scale structure through the chromosphere and corona has been brought to light by high-resolution observations over the last couple of decades. This fine-scale sturcture represents inhomogeneity that is thought to be perpendicular to the local magnetic fields. The implications of this form of inhomogeneity on wave propagation is still being uncovered, but is known to fundamentally change the nature of MHD wave modes. It also enables interesting physics to arise including resonances, turbulence and instabilities. Here we review some of the key insights into how the inhomogeneity influences Alfv\'enic wave propagation through the Sun's atmosphere, discussing both inhomogeneities parallel and perpendicular to the magnetic field.