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Gyrokinetic Theory and Dynamics of the Tokamak Edge
Author(s) -
Scott B.
Publication year - 2016
Publication title -
contributions to plasma physics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.531
H-Index - 47
eISSN - 1521-3986
pISSN - 0863-1042
DOI - 10.1002/ctpp.201610057
Subject(s) - physics , tokamak , microturbulence , turbulence , wavelength , mach number , momentum (technical analysis) , gyrokinetics , angular momentum , plasma , classical mechanics , magnetic field , mechanics , computational physics , quantum mechanics , finance , economics
The validity of modern gyrokinetic field theory is assessed for the tokamak edge. The basic structure of the Lagrangian and resulting equations and their conservation laws is reviewed. The conventional microturbulence ordering for expansion is small potential/arbitrary wavelength. The equilibrium ordering for expansion is long wavelength/arbitrary amplitude. The long‐wavelength form of the conventional Lagrangian is derived in detail. The two Lagrangians are shown to match at long wavelength if the E × B Mach number is small enough for its corrections to the gyroaveraging to be neglected. Therefore, the conventional derivation and its Lagrangian can be used at all wavelengths if these conditions are satisfied. Additionally, dynamical compressibility of the magnetic field can be neglected if the plasma beta is small. This allows general use of a shear‐Alfvén Lagrangian for edge turbulence and self consistent equilibrium‐scale phenomena for flows, currents, and heat fluxes for conventional tokamaks without further modification by higher‐order terms. Corrections in polarisation and toroidal angular momentum transport due to these higher‐order terms for global edge turbulence computations are shown to be small. (© 2016 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)