Faraday-Fresnel rotation and splitting of orbital angular momentum carrying waves in a rotating plasma

TL;DR

This paper uncovers and analyzes the rotational Faraday-Fresnel effect in a rotating plasma, showing how plasma rotation causes phase shifts and splitting of orbital angular momentum waves, with implications for wave propagation in magnetized plasmas.

Contribution

It introduces the concept of Faraday-Fresnel rotation for OAM waves in rotating plasma and explains its origin through dispersion relation analysis, highlighting new effects on wave phase and group velocity.

Findings

Rotation induces a non-zero phase shift between OAM eigenmodes.

Rotation causes splitting of wave packet envelopes based on azimuthal mode.

The effect is linked to Doppler, centrifugal, and Coriolis forces.

Abstract

Rotational Fresnel drag - or orbital Faraday rotation - in a rotating magnetised plasma is uncovered and studied analytically for Trivelpiece-Gould and Whistler-Helicon waves carrying orbital angular momentum (OAM). Plasma rotation is shown to introduce a non-zero phase shift between OAM-carrying eigenmodes with opposite helicities, similarly to the phase-shift between spin angular momentum eigenmodes associated with the classical Faraday effect in a magnetised plasma at rest. By examining the dispersion relation for these two low-frequency modes in a Brillouin rotating plasma, this Faraday-Fresnel rotation effect is traced back to the combined effects of Doppler shift, centrifugal forces and Coriolis forces. In addition, rotation is further shown to lead to rotation- and azimuthal mode-dependent longitudinal group velocity, therefore predicting the Faraday-Fresnel splitting of the enveloppe of a wave packet containing a superposition of OAM-carrying eigenmodes with opposite helicities.