Rotating Alfv\'en waves in rotating plasmas

TL;DR

This paper investigates how rotating magnetized plasmas interact with torsional Alfvén waves carrying orbital angular momentum, revealing mechanisms for angular momentum transfer and effects like orbital Faraday rotation.

Contribution

It demonstrates the coupling between plasma rotation and OAM-carrying Alfvén waves, deriving the rotation frequency and torque expressions for these interactions.

Findings

Rotation causes orbital Faraday rotation effects.

Angular momentum transfer from waves to plasma is quantified.

Derived dispersion relation for modes with opposite OAM.

Abstract

Angular momentum coupling between a rotating magnetized plasma and torsional Alfv\'en waves carrying orbital angular momentum (OAM) is examined. It is not only demonstrated that rotation is the source of Fresnel-Faraday rotation - or orbital Faraday rotation effects - for OAM carrying Alfv\'en waves, but also that angular momentum from an OAM carrying Alfv\'en wave can be transferred to a rotating plasma through the inverse process. For the direct process, the transverse structure angular rotation frequency is derived by considering the dispersion relation for modes with opposite OAM content. For the inverse process, the torque exerted on the plasma is derived as a function of wave and plasma parameters.