Spin Hall effect of radiofrequency waves in magnetized plasmas

TL;DR

This paper investigates the spin Hall effect of radiofrequency waves in magnetized plasmas, revealing significant deviations from traditional ray-tracing predictions, with implications for fusion plasma modeling.

Contribution

It demonstrates the importance of the spin Hall effect in radiofrequency wave propagation in magnetized plasmas and provides a gauge-invariant theoretical framework for its analysis.

Findings

Radiofrequency waves can deviate by up to ten wavelengths due to the spin Hall effect.

Theoretical predictions align with full-wave simulations, confirming the effect's significance.

The effect impacts wave trajectory modeling in fusion plasma experiments.

Abstract

In inhomogeneous media, electromagnetic-wave rays deviate from the trajectories predicted by the leading-order geometrical optics. This effect, called the spin Hall effect of light, is typically neglected in ray-tracing codes used for modeling waves in plasmas. Here, we demonstrate that the spin Hall effect can be significant for radiofrequency waves in toroidal magnetized plasmas whose parameters are in the ballpark of those used in fusion experiments. For example, an electron-cyclotron wave beam can deviate by as large as ten wavelengths ($\sim 0.1\,\text{m}$) relative to the lowest-order ray trajectory in the poloidal direction. We calculate this displacement using gauge-invariant ray equations of extended geometrical optics, and we also compare our theoretical predictions with full-wave simulations.