Noether derivation of exact conservation laws for dissipationless reduced-fluid models

TL;DR

This paper derives energy-momentum conservation laws for reduced-fluid models using Noether's method, revealing effects like polarization, magnetization, and intrinsic torque that influence plasma rotation.

Contribution

It introduces a novel derivation of conservation laws for reduced-fluid models via Noether's method, highlighting the role of asymmetry and intrinsic torque in plasma dynamics.

Findings

Reduced canonical energy-momentum tensor exhibits polarization and magnetization effects.

Asymmetry in the stress tensor leads to intrinsic torque in plasma.

Intrinsic torque can drive spontaneous toroidal rotation in tokamaks.

Abstract

The energy-momentum conservation laws for general reduced-fluid (e.g., gyrofluid) models are derived by Noether method from a general reduced variational principle. The reduced canonical energy-momentum tensor (which is explicitly asymmetric and has the Minkowski form) exhibits polarization and magnetization effects associated with dynamical reduction. In particular, the asymmetry in the reduced canonical momentum-stress tensor produces a non-vanishing reduced intrinsic torque that can drive spontaneous toroidal rotation in axisymmetric tokamak plasmas.