Electromagnetic theory of turbulent acceleration of parallel flow and momentum conservation

TL;DR

This paper demonstrates that electromagnetic turbulent acceleration can generate intrinsic parallel plasma flow without violating momentum conservation, by identifying the correct conserved quantity involving gyrocenter canonical momentum.

Contribution

It clarifies the role of electromagnetic turbulence in intrinsic flow generation and establishes a conservation law for total parallel momentum including electromagnetic fields.

Findings

Electromagnetic turbulent acceleration does not contradict momentum conservation.

The conserved quantity is the total gyrocenter parallel canonical momentum.

A conservation equation for total parallel momentum including electromagnetic fields is derived.

Abstract

Intrinsic flow in plasma physics is a long-standing puzzle, since it is difficult to understand its origin without contradiction to momentum conservation in conventional wisdom. It is proved that the electromagnetic turbulent acceleration as a candidate for intrinsic parallel flow generation driven by pressure gradient along the total magnetic field line does not contradict momentum conservation. The conserved quantity corresponding to axial symmetry is the total gyrocenter parallel canonical momentum carried by both species or the total gyrocenter parallel momentum including the ion gyrocenter kinematic momentum and electromagnetic fields momentum, but not the ion kinematic momentum, or even the ion parallel flow. A conservation equation of total parallel momentum including the ion particles' kinematic momentum and electromagnetic fields momentum is also presented.