Image rotation in plasmas

TL;DR

This study reports the first observation of wave image rotation in plasmas, demonstrating control over wave structure rotation through plasma manipulation, with implications for fundamental physics and remote sensing technologies.

Contribution

It provides the first experimental evidence of wave image rotation in plasmas and shows control over this rotation using plasma rotation, aligning with light dragging theory.

Findings

Significant wave rotation observed in Alfvén waves

Control of wave rotation achieved via biased electrodes

Experimental results match light dragging theory for isotropic media

Abstract

Because of the speed of light compared to material motion, the dragging of light is difficult to observe under laboratory conditions. Here we report on the first observation of image rotation, i. e. a dragging by the medium of the wave's transverse structure, of Alfv\'en waves in plasmas. Exploiting the naturally slow group velocity of these waves, significant wave rotation is achieved for modest angular frequency. Control over the rotation of the wave's structure is demonstrated through the plasma rotation imposed by biased electrodes. Remarkably, experimental results are well reproduced by light dragging theory derived for isotropic media, even if magnetized plasmas are anisotropic. In addition to offering new insights into the fundamental issue of angular momentum coupling between waves and media, these findings also open possibilities for new remote rotation sensing tools.