Energetic bounds on gyrokinetic instabilities. Part I: Fundamentals

TL;DR

This paper derives universal energetic bounds on the growth of gyrokinetic instabilities, applicable to both linear and nonlinear regimes across various plasma geometries and conditions.

Contribution

It introduces fundamental upper bounds on free energy growth in gyrokinetics, independent of specific plasma configurations or collision effects.

Findings

Bounds apply to all local gyrokinetic instabilities

Results are valid for linear and nonlinear growth

Applicable to diverse plasma geometries

Abstract

Upper bounds on the growth of free energy in gyrokinetics are derived. These bounds apply to all local gyrokinetic instabilities in the geometry of a flux tube, i.e. a slender volume of plasma aligned with the magnetic field, regardless of the geometry of field, the number of particle species, or collisions. The results apply both to linear instabilities and to the nonlinear growth of finite-amplitude fluctuations.