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Abstract
This article extends theoretical details based on a short paper originally submitted
to the 2022 EPS conference in plasma physics [1]. The quasilinear theory of resonant transport regimes in a tokamak is developed for the general case of orbits forming various classes separated in phase space by homoclinic orbits with infinite bounce time. Beyond standard orbits (banana and passing orbits) also all types of nonstandard orbits (e.g. “potato” orbits) are taken into account. In case of a weak radial electric field, such orbits are usually present only near the magnetic axis. If the radial electric field cannot be treated as weak, there can be arbitrary many classes, located elsewhere. The present approach covers all such cases and is demonstrated on a specific example of a radial electric field profile. The resulting quasilinear kinetic equation is applicable to compute neoclassical toroidal viscous (NTV) torque in a tokamak with nonaxisymmetric magnetic field perturbations. A fully nonlocal approach to NTV computation has been realized in the upgraded version of the code NEORT. Based on a generalization of magnetic flux surfaces to drift surfaces, the notion of a local thermodynamic equilibrium is extended for our purpose. We obtain an expression for the integral toroidal torque within a chosen flux surface and dicuss means to compute such integrals taking singularities in bounce and precession frequencies into account.
to the 2022 EPS conference in plasma physics [1]. The quasilinear theory of resonant transport regimes in a tokamak is developed for the general case of orbits forming various classes separated in phase space by homoclinic orbits with infinite bounce time. Beyond standard orbits (banana and passing orbits) also all types of nonstandard orbits (e.g. “potato” orbits) are taken into account. In case of a weak radial electric field, such orbits are usually present only near the magnetic axis. If the radial electric field cannot be treated as weak, there can be arbitrary many classes, located elsewhere. The present approach covers all such cases and is demonstrated on a specific example of a radial electric field profile. The resulting quasilinear kinetic equation is applicable to compute neoclassical toroidal viscous (NTV) torque in a tokamak with nonaxisymmetric magnetic field perturbations. A fully nonlocal approach to NTV computation has been realized in the upgraded version of the code NEORT. Based on a generalization of magnetic flux surfaces to drift surfaces, the notion of a local thermodynamic equilibrium is extended for our purpose. We obtain an expression for the integral toroidal torque within a chosen flux surface and dicuss means to compute such integrals taking singularities in bounce and precession frequencies into account.
Original language  English 

Article number  012012 
Journal  Journal of Physics: Conference Series 
Volume  2397 
Issue number  1 
DOIs  
Publication status  Published  12 Dec 2022 
Event  Joint VarennaLausanne International Workshop 2022: Theory of Fusion Plasmas  Villa Monastero, Varenna, Italy Duration: 11 Sept 2022 → 16 Sept 2022 
ASJC Scopus subject areas
 Physics and Astronomy(all)
Projects
 1 Finished

EUROFusion  Transport and Heating in Fusion Plasmas
Kernbichler, W., Albert, C., Eder, M., Kasilov, S., Markl, M., Buchholz, R., Graßler, G. S., Kamendje, R. L., Babin, R. & Lainer, P.
1/01/21 → 31/12/23
Project: Research project