Evaluation of toroidal torque by nonresonant magnetic perturbations in tokamaks for resonant transport regimes using a Hamiltonian approach
Abstract
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. The resulting expressions are shown to match the existing analytical results in the large aspect ratio limit. Numerical results from the newly developed code NEORT are compared to calculations by the quasilinear version of the code NEO2 at low collisionalities. The importance of the magnetic shear term in the magnetic drift frequency and a significant effect of the magnetic drift on driftorbit resonances are demonstrated.
 Authors:
 Fusion@ÖAW, Institut für Theoretische Physik  Computational Physics, Technische Universität Graz, Petersgasse 16, 8010 Graz (Austria)
 (Ukraine)
 Publication Date:
 OSTI Identifier:
 22599890
 Resource Type:
 Journal Article
 Resource Relation:
 Journal Name: Physics of Plasmas; Journal Volume: 23; Journal Issue: 8; Other Information: (c) 2016 EURATOM; Country of input: International Atomic Energy Agency (IAEA)
 Country of Publication:
 United States
 Language:
 English
 Subject:
 70 PLASMA PHYSICS AND FUSION TECHNOLOGY; ASPECT RATIO; AXIAL SYMMETRY; COMPARATIVE EVALUATIONS; DISTURBANCES; EQUILIBRIUM; HAMILTONIANS; MAGNETIC SURFACES; NEOCLASSICAL TRANSPORT THEORY; PERTURBATION THEORY; PLASMA; QUASILINEAR PROBLEMS; TOKAMAK DEVICES; TORQUE; VISCOSITY
Citation Formats
Albert, Christopher G., Heyn, Martin F., Kapper, Gernot, Kernbichler, Winfried, Martitsch, Andreas F., Kasilov, Sergei V., and Institute of Plasma Physics, National Science Center “Kharkov Institute of Physics and Technology,” ul. Akademicheskaya 1, 61108 Kharkov. Evaluation of toroidal torque by nonresonant magnetic perturbations in tokamaks for resonant transport regimes using a Hamiltonian approach. United States: N. p., 2016.
Web. doi:10.1063/1.4961084.
Albert, Christopher G., Heyn, Martin F., Kapper, Gernot, Kernbichler, Winfried, Martitsch, Andreas F., Kasilov, Sergei V., & Institute of Plasma Physics, National Science Center “Kharkov Institute of Physics and Technology,” ul. Akademicheskaya 1, 61108 Kharkov. Evaluation of toroidal torque by nonresonant magnetic perturbations in tokamaks for resonant transport regimes using a Hamiltonian approach. United States. doi:10.1063/1.4961084.
Albert, Christopher G., Heyn, Martin F., Kapper, Gernot, Kernbichler, Winfried, Martitsch, Andreas F., Kasilov, Sergei V., and Institute of Plasma Physics, National Science Center “Kharkov Institute of Physics and Technology,” ul. Akademicheskaya 1, 61108 Kharkov. Mon .
"Evaluation of toroidal torque by nonresonant magnetic perturbations in tokamaks for resonant transport regimes using a Hamiltonian approach". United States.
doi:10.1063/1.4961084.
@article{osti_22599890,
title = {Evaluation of toroidal torque by nonresonant magnetic perturbations in tokamaks for resonant transport regimes using a Hamiltonian approach},
author = {Albert, Christopher G. and Heyn, Martin F. and Kapper, Gernot and Kernbichler, Winfried and Martitsch, Andreas F. and Kasilov, Sergei V. and Institute of Plasma Physics, National Science Center “Kharkov Institute of Physics and Technology,” ul. Akademicheskaya 1, 61108 Kharkov},
abstractNote = {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. The resulting expressions are shown to match the existing analytical results in the large aspect ratio limit. Numerical results from the newly developed code NEORT are compared to calculations by the quasilinear version of the code NEO2 at low collisionalities. The importance of the magnetic shear term in the magnetic drift frequency and a significant effect of the magnetic drift on driftorbit resonances are demonstrated.},
doi = {10.1063/1.4961084},
journal = {Physics of Plasmas},
number = 8,
volume = 23,
place = {United States},
year = {Mon Aug 15 00:00:00 EDT 2016},
month = {Mon Aug 15 00:00:00 EDT 2016}
}

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 thatmore »

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