Journal article
Reimagining full wave rf quasilinear theory in a tokamak
Journal of plasma physics, Vol.87(2), 905870215
04/01/2021
DOI: 10.1017/S002237782100026X
Abstract
The velocity dependent resonant interaction of particles with applied radiofrequency (rf) waves during heating and current drive in the presence of pitch angle scattering collisions gives rise to narrow collisional velocity space boundary layers that dramatically enhance the role of collisions as recently shown by Catto (J. Plasma Phys., vol. 86, 2020, 815860302). The behaviour is a generalization of the narrow collisional boundary layer that forms during Landau damping as found by Johnston (Phys. Fluids, vol. 14, 1971, pp. 2719-2726) and Auerbach (Phys. Fluids, vol. 20, 1977, pp. 1836-1844). For a wave of parallel wave number k(parallel to) interacting with weakly collisional plasma species of collision frequency. and thermal speed vth, the effective collision frequency becomes of order.(k(parallel to) v(th)/nu)(2/3) >> nu. The narrow boundary layers that arise because of the diffusive nature of the collisions allow a physically meaningful wave-particle interaction time to be defined that is the inverse of this effective collision frequency. The collisionality implied by the narrow boundary layer results in changes in the standard quasilinear treatment of applied rf fields in tokamaks while remaining consistent with causality. These changes occur because successive poloidal interactions with the rf are correlated in tokamak geometry and because the resonant velocity space dependent interactions are controlled by the spatial and temporal behaviour of the perturbed full wave fields rather than just the spatially local Landau and Doppler shifted cyclotron wave-particle resonance condition associated with unperturbedmotion of the particles. The correlation of successive poloidal circuits of the tokamak leads to the appearance in the quasilinear operator of transit averaged resonance conditions localized in velocity space boundary layers that maintain negative definite entropy production.
Details
- Title: Subtitle
- Reimagining full wave rf quasilinear theory in a tokamak
- Creators
- Peter J. Catto - Massachusetts Institute of TechnologyElizabeth A. Tolman - Massachusetts Institute of Technology
- Resource Type
- Journal article
- Publication Details
- Journal of plasma physics, Vol.87(2), 905870215
- DOI
- 10.1017/S002237782100026X
- ISSN
- 0022-3778
- eISSN
- 1469-7807
- Publisher
- Cambridge Univ Press
- Number of pages
- 33
- Grant note
- DE-FG02-91ER-54109 / U. S. Department of Energy; United States Department of Energy (DOE) Bezos Membership at the Institute for Advanced Study
- Language
- English
- Date published
- 04/01/2021
- Academic Unit
- Physics and Astronomy
- Record Identifier
- 9985113757202771
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