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Recent progress of magnetic reconnection research in the MAST spherical tokamak

Tanabe, H.; Yamada, T.; Watanabe, T.; Gi, K.; Inomoto, M.; Imazawa, R.; Gryaznevich, M.; Michael, Clive; Crowley, B.; Conway, N. J.; Scannell, R.; Harrison, J.; Fitzgerald, I.; Meakins, A.; Hawkes, N.; McClements, K. G.; O'Gorman, T.; Cheng, C. Z.; Ono, Y.

Description

In the last three years, magnetic reconnection research in the MAST spherical tokamak achieved major progress by the use of new 32 chord ion Doppler tomography and 130 channel YAG and 300 channel Ruby Thomson scattering diagnostics. In addition to the previously achieved high power plasma heating during merging, detailed full temperature profile measurements including the diffusion region have been achieved for the first time. 2D imaging measurements of ion and electron temperature...[Show more]

dc.contributor.authorTanabe, H.
dc.contributor.authorYamada, T.
dc.contributor.authorWatanabe, T.
dc.contributor.authorGi, K.
dc.contributor.authorInomoto, M.
dc.contributor.authorImazawa, R.
dc.contributor.authorGryaznevich, M.
dc.contributor.authorMichael, Clive
dc.contributor.authorCrowley, B.
dc.contributor.authorConway, N. J.
dc.contributor.authorScannell, R.
dc.contributor.authorHarrison, J.
dc.contributor.authorFitzgerald, I.
dc.contributor.authorMeakins, A.
dc.contributor.authorHawkes, N.
dc.contributor.authorMcClements, K. G.
dc.contributor.authorO'Gorman, T.
dc.contributor.authorCheng, C. Z.
dc.contributor.authorOno, Y.
dc.date.accessioned2017-04-11T01:32:24Z
dc.date.available2017-04-11T01:32:24Z
dc.identifier.issn1070-664X
dc.identifier.urihttp://hdl.handle.net/1885/114525
dc.description.abstractIn the last three years, magnetic reconnection research in the MAST spherical tokamak achieved major progress by the use of new 32 chord ion Doppler tomography and 130 channel YAG and 300 channel Ruby Thomson scattering diagnostics. In addition to the previously achieved high power plasma heating during merging, detailed full temperature profile measurements including the diffusion region have been achieved for the first time. 2D imaging measurements of ion and electron temperature profiles have revealed that magnetic reconnection mostly heats ions globally in the downstream region of outflow jet and electrons locally around the X-point. The toroidal field in MAST “over 0.3T” strongly inhibits cross-field thermal transport, and the characteristic peaked electron temperature profile around the X-point is sustained on a millisecond time scale. In contrast, ions are mostly heated in the downstream region of outflow acceleration and around the stagnation point formed by reconnected flux mostly by viscosity dissipation and shock-like compressional damping of the outflow jet. Toroidal confinement also contributes to the characteristic ion temperature profile, forming a ring structure aligned with the closed flux surface. There is an effective confinement of the downstream thermal energy due to a thick layer of reconnected flux. The characteristic structure is sustained for longer than an ion-electron energy relaxation time ( 4 ms), and the energy exchange between ions and electrons contributes to the bulk electron heating in the downstream region. The toroidal guide field mostly contributes to the formation of a localized electron heating structure around the X-point but not to bulk ion heating downstream.
dc.description.sponsorshipThis work was supported by Grant-in-Aid for Scientific Research 22246119, 22656208, 25820434, 15H05750, and 15K20921, JSPS Core-to-Core program 22001, JSPS institutional Program for Young Researcher Overseas Visits, and NIFS Collaboration Research Programs (NIFS11KNWS001, NIFSKLEH024 and NIFS11KUTR060). This work was also partly funded by the RCUK Energy Programme under Grant No. EP/I501045 and the European Communities.
dc.format8 pages
dc.format.mimetypeapplication/pdf
dc.publisherAIP Publishing
dc.rights© 2017 Author(s). All article content, except where otherwise noted, is licensed under a Creative Commons Attribution (CC BY) license (http://creativecommons.org/licenses/by/4.0/).
dc.sourcePhysics of Plasmas
dc.subjectmagnetic
dc.subjectreconnection
dc.subjectMAST
dc.subjectspherical
dc.subjecttokamak
dc.subject32 chord ion
dc.subjectDoppler
dc.subjecttomography
dc.subject130 channel YAG
dc.subject300 channel Ruby Thomson
dc.subjectscattering
dc.subjectdiagnostics
dc.subjectplasma
dc.subjectheating
dc.titleRecent progress of magnetic reconnection research in the MAST spherical tokamak
dc.typeJournal article
local.identifier.citationvolume24
dcterms.dateAccepted2017-02-16
dc.date.issued2017
local.publisher.urlhttps://publishing.aip.org/
local.type.statusPublished Version
local.contributor.affiliationMichael, Clive, Plasma Research Laboratory, CPMS Research School of Physics and Engineering, The Australian National University
local.identifier.essn1089-7674
local.bibliographicCitation.issue5
local.bibliographicCitation.startpage056108
local.identifier.doi10.1063/1.4977922
dcterms.accessRightsOpen Access
CollectionsANU Research Publications

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