Comment on "Energy Transfer and Dual Cascade in Kinetic Magnetized Plasma Turbulence"

TL;DR

This paper critiques previous claims about energy transfer directions in kinetic magnetized plasma turbulence, using absolute equilibria and fundamental dynamics to clarify transfer behaviors and correct mathematical errors.

Contribution

It provides a corrected analysis of transfer directions in plasma turbulence, challenging prior constraints and emphasizing the role of absolute equilibria and fundamental dynamics.

Findings

Previous constraints on transfer directions are incorrect.

Absolute equilibria help clarify transfer and cascade behaviors.

Mathematical errors in prior analysis are identified and corrected.

Abstract

We argue that the constraints on transfers, given in the Letter [G. Plunk and T. Tatsuno, Phys. Rev. Lett. {\bf 106}, 165003 (2011)], but not correctly, do not give the transfer and/or cascade directions which however can be assisted by the absolute equilibria calculated in this Comment, following Kraichnan [R. H. Kraichnan, Phys. Fluids {\bf 102}, 1417 (1967)]. One of the important statements about the transfers with only one or no diagonal component can be shown to be inappropriate according to the fundamental dynamics. Some mathematical mistakes are pointed out.