Microtearing modes in tokamak discharges

Journal Article · Wed Jun 15 00:00:00 EDT 2016 · Physics of Plasmas

DOI:https://doi.org/10.1063/1.4953609· OSTI ID:22600119

Rafiq, T.; Kritz, A. H. ^[1]; Weiland, J. ^[2]; Luo, L. ^[3]; Pankin, A. Y. ^[4]

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1. Department of Physics, Lehigh University, Bethlehem, Pennsylvania 18015 (United States)
2. Department of Applied Physics, Chalmers University, S41296 Gothenburg (Sweden)
3. IBM Research, Oak Ridge, Tennessee 37831 (United States)
4. Tech-X Corporation, Boulder, Colorado 80308 (United States)

Microtearing modes (MTMs) have been identified as a source of significant electron thermal transport in tokamak discharges. In order to describe the evolution of these discharges, it is necessary to improve the prediction of electron thermal transport. This can be accomplished by utilizing a model for transport driven by MTMs in whole device predictive modeling codes. The objective of this paper is to develop the dispersion relation that governs the MTM driven transport. A unified fluid/kinetic approach is used in the development of a nonlinear dispersion relation for MTMs. The derivation includes the effects of electrostatic and magnetic fluctuations, arbitrary electron-ion collisionality, electron temperature and density gradients, magnetic curvature, and the effects associated with the parallel propagation vector. An iterative nonlinear approach is used to calculate the distribution function employed in obtaining the nonlinear parallel current and the nonlinear dispersion relation. The third order nonlinear effects in magnetic fluctuations are included, and the influence of third order effects on a multi-wave system is considered. An envelope equation for the nonlinear microtearing modes in the collision dominant limit is introduced in order to obtain the saturation level. In the limit that the mode amplitude does not vary along the field line, slab geometry, and strong collisionality, the fluid dispersion relation for nonlinear microtearing modes is found to agree with the kinetic dispersion relation.

• OSTI ID: 22600119
• Journal Information: Physics of Plasmas, Vol. 23, Issue 6; Other Information: (c) 2016 Author(s); Country of input: International Atomic Energy Agency (IAEA); ISSN 1070-664X
• Country of Publication: United States
• Language: English

Related Subjects

70 PLASMA PHYSICS AND FUSION TECHNOLOGY
AMPLITUDES
COMPUTERIZED SIMULATION
DISPERSION RELATIONS
DISPERSIONS
DISTRIBUTION FUNCTIONS
ELECTRON TEMPERATURE
ELECTRON-ION COLLISIONS
ELECTRONS
FLUCTUATIONS
FLUIDS
GEOMETRY
IONS
ITERATIVE METHODS
NONLINEAR PROBLEMS
TOKAMAK DEVICES
TRANSPORT THEORY
VECTORS