The Eulerian variational formulation of the gyrokinetic system in general spatial coordinates

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Hauptverfasser: Sugama, H., Matsuoka, S., Nunami, M., Satake, S.
Format: Preprint
Veröffentlicht: 2020
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_version_ 1866929389375062016
author Sugama, H.
Matsuoka, S.
Nunami, M.
Satake, S.
author_facet Sugama, H.
Matsuoka, S.
Nunami, M.
Satake, S.
contents The Eulerian variational formulation of the gyrokinetic system with electrostatic turbulence is presented in general spatial coordinates by extending our previous work [H. Sugama, {\it et al}., Phys.\ Plasmas {\bf 25}, 102506 (2018)]. The invariance of the Lagrangian of the system under an arbitrary spatial coordinate transformation is used to derive the local momentum balance equation satisfied by the gyrocenter distribution functions and the turbulent potential which are given as solutions of the governing equations. This derivation is in contrast with the conventional method using the spatial translation in which the asymmetric canonical pressure tensor generally enters the momentum balance equation. In the present study, the variation of the Lagrangian density with respect to the metric tensor is taken to directly obtain the symmetric pressure tensor which includes the effect of turbulence on the momentum transport. In addition, it is shown in this work how the momentum balance is modified when the collision and/or external source terms are added to the gyrokinetic equation. The results obtained here are considered useful for global gyrokinetic simulations investigating both neoclassical and turbulent transport processes even in general non-axisymmetric toroidal systems.
format Preprint
id arxiv_https___arxiv_org_abs_2009_00259
institution arXiv
publishDate 2020
record_format arxiv
spellingShingle The Eulerian variational formulation of the gyrokinetic system in general spatial coordinates
Sugama, H.
Matsuoka, S.
Nunami, M.
Satake, S.
Plasma Physics
The Eulerian variational formulation of the gyrokinetic system with electrostatic turbulence is presented in general spatial coordinates by extending our previous work [H. Sugama, {\it et al}., Phys.\ Plasmas {\bf 25}, 102506 (2018)]. The invariance of the Lagrangian of the system under an arbitrary spatial coordinate transformation is used to derive the local momentum balance equation satisfied by the gyrocenter distribution functions and the turbulent potential which are given as solutions of the governing equations. This derivation is in contrast with the conventional method using the spatial translation in which the asymmetric canonical pressure tensor generally enters the momentum balance equation. In the present study, the variation of the Lagrangian density with respect to the metric tensor is taken to directly obtain the symmetric pressure tensor which includes the effect of turbulence on the momentum transport. In addition, it is shown in this work how the momentum balance is modified when the collision and/or external source terms are added to the gyrokinetic equation. The results obtained here are considered useful for global gyrokinetic simulations investigating both neoclassical and turbulent transport processes even in general non-axisymmetric toroidal systems.
title The Eulerian variational formulation of the gyrokinetic system in general spatial coordinates
topic Plasma Physics
url https://arxiv.org/abs/2009.00259