Geng, Chen, Dickinson, David orcid.org/0000-0002-0868-211X and Wilson, Howard Read orcid.org/0000-0003-3333-7470 (2020) The physics of a small-scale tearing mode in collisionless slab plasmas. Plasma Physics and Controlled Fusion. 085009. ISSN 1361-6587
Abstract
Microtearing modes have been widely reported as a tearing parity electron temperature gradient driven plasma instability that leads to fine scale tearing of the magnetic flux surfaces thereby resulting in reconnection of magnetic field lines and formation of magnetic islands. In slab geometry it has previously been shown that the drive mechanism requires a finite collision frequency. However, recent gyrokinetic simulations in toroidal systems have found a microtearing mode existing at low and zero collision frequency. It is shown here that linear gyrokinetic simulations can demonstrate a collisionless fine-scale tearing parity instability even in slab geometry. Detailed studies reveal that these slab modes are sensitive to electron finite Larmor radius effects, and have a radial wavenumber much smaller than the binormal wavenumber, which is comparable to the ion Larmor radius. Furthermore, they exist even in the electrostatic limit and electromagnetic effects actually have a stabilising influence on this collisionless tearing mode. An analytic model shows that this collisionless small scale tearing mode is consistent with a tearing parity slab electron temperature gradient (ETG) mode, which can be more unstable than the twisting parity ETG mode that is often studied. This small-scale tearing parity mode can lead to magnetic islands, which, in turn, can influence turbulent transport in magnetised plasmas.
Metadata
Item Type: | Article |
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Authors/Creators: |
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Copyright, Publisher and Additional Information: | © 2020 The Author(s). |
Dates: |
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Institution: | The University of York |
Academic Units: | The University of York > Faculty of Sciences (York) > Physics (York) |
Funding Information: | Funder Grant number EPSRC EP/R034737/1 |
Depositing User: | Pure (York) |
Date Deposited: | 06 Aug 2020 09:10 |
Last Modified: | 08 Feb 2025 00:37 |
Published Version: | https://doi.org/10.1088/1361-6587/ab97f1 |
Status: | Published |
Refereed: | Yes |
Identification Number: | 10.1088/1361-6587/ab97f1 |
Open Archives Initiative ID (OAI ID): | oai:eprints.whiterose.ac.uk:164163 |
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Description: The physics of a small-scale tearing mode in collisionless slab plasmas
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Filename: Geng_2020_Plasma_Phys._Control._Fusion_62_085009.pdf
Description: The physics of a small-scale tearing mode in collisionless slab plasmas
Licence: CC-BY 2.5