Evaluation of the toroidal torque driven by external nonresonant nonaxisymmetric magnetic field perturbations in a tokamak
Abstract
The toroidal torque driven by external nonresonant magnetic perturbations (neoclassical toroidal viscosity) is an important momentum source affecting the toroidal plasma rotation in tokamaks. The wellknown forceflux relation directly links this torque to the nonambipolar neoclassical particle fluxes arising due to the violation of the toroidal symmetry of the magnetic field. Here, a quasilinear approach for the numerical computation of these fluxes is described, which reduces the dimension of a standard neoclassical transport problem by one without model simplifications of the linearized drift kinetic equation. The only limiting condition is that the nonaxisymmetric perturbation field is small enough such that the effect of the perturbation field on particle motion within the flux surface is negligible. Therefore, in addition to most of the transport regimes described by the banana (bounce averaged) kinetic equation also such regimes as, e.g., rippleplateau and resonant diffusion regimes are naturally included in this approach. Based on this approach, a quasilinear version of the code NEO2 [W. Kernbichler et al., Plasma Fusion Res. 3, S1061 (2008).] has been developed and benchmarked against a few analytical and numerical models. Results from NEO2 stay in good agreement with results from these models in their pertinent range of validity.
 Authors:
 Fusion@ÖAW, Institut für Theoretische Physik—Computational Physics, Technische Universität Graz Petersgasse 16, A–8010 Graz (Austria)
 (Ukraine)
 MaxPlanck Institut für Plasmaphysik, D17491 Greifswald (Germany)
 Publication Date:
 OSTI Identifier:
 22303637
 Resource Type:
 Journal Article
 Resource Relation:
 Journal Name: Physics of Plasmas; Journal Volume: 21; Journal Issue: 9; Other Information: (c) 2014 EURATOM; Country of input: International Atomic Energy Agency (IAEA)
 Country of Publication:
 United States
 Language:
 English
 Subject:
 70 PLASMA PHYSICS AND FUSION TECHNOLOGY; AXIAL SYMMETRY; DISTURBANCES; KINETIC EQUATIONS; MAGNETIC FIELDS; MAGNETIC SURFACES; NEOCLASSICAL TRANSPORT THEORY; PERTURBATION THEORY; PLASMA; TOKAMAK DEVICES; TORQUE
Citation Formats
Kasilov, Sergei V., Institute of Plasma Physics National Science Center “Kharkov Institute of Physics and Technology” ul. Akademicheskaya 1, 61108 Kharkov, Kernbichler, Winfried, Martitsch, Andreas F., Heyn, Martin F., and Maassberg, Henning. Evaluation of the toroidal torque driven by external nonresonant nonaxisymmetric magnetic field perturbations in a tokamak. United States: N. p., 2014.
Web. doi:10.1063/1.4894479.
Kasilov, Sergei V., Institute of Plasma Physics National Science Center “Kharkov Institute of Physics and Technology” ul. Akademicheskaya 1, 61108 Kharkov, Kernbichler, Winfried, Martitsch, Andreas F., Heyn, Martin F., & Maassberg, Henning. Evaluation of the toroidal torque driven by external nonresonant nonaxisymmetric magnetic field perturbations in a tokamak. United States. doi:10.1063/1.4894479.
Kasilov, Sergei V., Institute of Plasma Physics National Science Center “Kharkov Institute of Physics and Technology” ul. Akademicheskaya 1, 61108 Kharkov, Kernbichler, Winfried, Martitsch, Andreas F., Heyn, Martin F., and Maassberg, Henning. 2014.
"Evaluation of the toroidal torque driven by external nonresonant nonaxisymmetric magnetic field perturbations in a tokamak". United States.
doi:10.1063/1.4894479.
@article{osti_22303637,
title = {Evaluation of the toroidal torque driven by external nonresonant nonaxisymmetric magnetic field perturbations in a tokamak},
author = {Kasilov, Sergei V. and Institute of Plasma Physics National Science Center “Kharkov Institute of Physics and Technology” ul. Akademicheskaya 1, 61108 Kharkov and Kernbichler, Winfried and Martitsch, Andreas F. and Heyn, Martin F. and Maassberg, Henning},
abstractNote = {The toroidal torque driven by external nonresonant magnetic perturbations (neoclassical toroidal viscosity) is an important momentum source affecting the toroidal plasma rotation in tokamaks. The wellknown forceflux relation directly links this torque to the nonambipolar neoclassical particle fluxes arising due to the violation of the toroidal symmetry of the magnetic field. Here, a quasilinear approach for the numerical computation of these fluxes is described, which reduces the dimension of a standard neoclassical transport problem by one without model simplifications of the linearized drift kinetic equation. The only limiting condition is that the nonaxisymmetric perturbation field is small enough such that the effect of the perturbation field on particle motion within the flux surface is negligible. Therefore, in addition to most of the transport regimes described by the banana (bounce averaged) kinetic equation also such regimes as, e.g., rippleplateau and resonant diffusion regimes are naturally included in this approach. Based on this approach, a quasilinear version of the code NEO2 [W. Kernbichler et al., Plasma Fusion Res. 3, S1061 (2008).] has been developed and benchmarked against a few analytical and numerical models. Results from NEO2 stay in good agreement with results from these models in their pertinent range of validity.},
doi = {10.1063/1.4894479},
journal = {Physics of Plasmas},
number = 9,
volume = 21,
place = {United States},
year = 2014,
month = 9
}

Toroidal torque generated by neoclassical viscosity caused by external nonresonant, nonaxisymmetric perturbations has a significant influence on toroidal plasma rotation in tokamaks. In this article, a derivation for the expressions of toroidal torque and radial transport in resonant regimes is provided within quasilinear theory in canonical actionangle variables. The proposed approach treats all lowcollisional quasilinear resonant neoclassical toroidal viscosity regimes including superbananaplateau and driftorbit resonances in a unified way and allows for magnetic drift in all regimes. It is valid for perturbations on toroidally symmetric flux surfaces of the unperturbed equilibrium without specific assumptions on geometry or aspect ratio. Themore »

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