Scaling laws for electron kinetic effects in tokamak scrape-off layer plasmas
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Published version
Author(s)
Power, D
Mijin, S
Wigram, M
Militello, F
Kingham, RJ
Type
Journal Article
Abstract
Tokamak edge (scrape-off layer (SOL)) plasmas can exhibit non-local transport in the direction parallel to the magnetic field due to steep temperature gradients. This effect along with its consequences has been explored at equilibrium for a range of conditions, from sheath-limited to detached, using the 1D kinetic electron code SOL-KiT, where the electrons are treated kinetically and compared to a self-consistent fluid model. Line-averaged suppression of the kinetic heat flux (compared to Spitzer-Härm) of up to 50% is observed, contrasting with up to 98% enhancement of the sheath heat transmission coefficient, γe. Simple scaling laws in terms of basic SOL parameters for both effects are presented. By implementing these scalings as corrections to the fluid model, we find good agreement with the kinetic model for target electron temperatures. It is found that the strongest kinetic effects in γe are observed at low-intermediate collisionalities, and tend to increase (keeping upstream collisionality fixed) at increasing upstream densities and temperatures. On the other hand, the heat flux suppression is found to increase monotonically as upstream collisionality decreases. The conditions simulated encompass collisionalities relevant to current and future tokamaks.
Date Issued
2023-08
Date Acceptance
2023-06-08
Citation
Nuclear Fusion, 2023, 63 (8), pp.1-16
ISSN
0029-5515
Publisher
IOP Publishing
Start Page
1
End Page
16
Journal / Book Title
Nuclear Fusion
Volume
63
Issue
8
Copyright Statement
© 2023 The Author(s). Published on behalf of IAEA by IOP Publishing Ltd. Original Content from this work may be used under the
terms of the Creative Commons Attribution 4.0 licence. Any
further distribution of this work must maintain attribution to the author(s) and
the title of the work, journal citation and DOI.
terms of the Creative Commons Attribution 4.0 licence. Any
further distribution of this work must maintain attribution to the author(s) and
the title of the work, journal citation and DOI.
License URL
Identifier
https://iopscience.iop.org/article/10.1088/1741-4326/acdca6
Publication Status
Published
Article Number
086013
Date Publish Online
2023-06-23