ECCD-induced sawtooth crashes at W7-X

dc.contributor.authorZanini, Marco
dc.contributor.authorLaqua, H.P.
dc.contributor.authorThomsen, H.
dc.contributor.authorStange, T.
dc.contributor.authorBrandt, Christian
dc.contributor.authorBraune, H.
dc.contributor.authorBrunner, Kai Jakob
dc.contributor.authorFuchert, G.
dc.contributor.authorHirsch, M.
dc.contributor.authorKnauer, J.
dc.contributor.authorHöfel, U.
dc.contributor.authorMarsen, S.
dc.contributor.authorPasch, E.
dc.contributor.authorRahbarnia, K.
dc.contributor.authorSchilling, Jonathan
dc.contributor.authorTurkin, Y.
dc.contributor.authorWolf, Robert C.
dc.contributor.authorZocco, Alessandro
dc.date.accessioned2022-02-14T15:36:29Z
dc.date.available2022-02-14T15:36:29Z
dc.date.issued2020-09-09
dc.date.updated2022-02-06T01:18:10Z
dc.description.abstractThe optimised superconducting stellarator W7-X generates its rotational transform by means of external coils, therefore no toroidal current is necessary for plasma confinement. Electron cyclotron current drive experiments were conducted for strikeline control and safe divertor operation. During current drive experiments periodic and repetitive crashes of the central electron temperature, similar to sawtooth crashes in tokamaks, were detected. Measurements from soft x-ray tomography and electron cyclotron emission show that the crashes are preceded by weak oscillating precursors and a displacement of the plasma core, consistent with a (m, n) = (1, 1) mode. The displacement occurs within 100μs, followed by expulsion and redistribution of the core into the external part of the plasma. Two types of crashes, with different frequencies and amplitudes are detected in the experimental program. For these non-stationary parameters a strong dependence on the toroidal current is found. A 1-D heuristic model for current diffusion is proposed as a first step to explain the characteristic crash time. Initial results show that the modelled current diffusion timescale is consistent with the initial crash frequency and that the toroidal current rise shifts the position where the instability is triggered, resulting in larger crash amplitudes.en
dc.description.sponsorshipEC/H2020/633053/EU/Implementation of activities described in the Roadmap to Fusion during Horizon 2020 through a Joint programme of the members of the EUROfusion consortium/Euratomen
dc.identifier.eissn1741-4326
dc.identifier.issn0029-5515
dc.identifier.urihttps://depositonce.tu-berlin.de/handle/11303/16369
dc.identifier.urihttp://dx.doi.org/10.14279/depositonce-15145
dc.language.isoenen
dc.rights.urihttps://creativecommons.org/licenses/by/3.0/en
dc.subject.ddc530 Physikde
dc.subject.otherstellaratoren
dc.subject.othersawtoothen
dc.subject.otherECCDen
dc.titleECCD-induced sawtooth crashes at W7-Xen
dc.typeArticleen
dc.type.versionpublishedVersionen
dcterms.bibliographicCitation.articlenumber106021en
dcterms.bibliographicCitation.doi10.1088/1741-4326/aba72ben
dcterms.bibliographicCitation.issue10en
dcterms.bibliographicCitation.journaltitleNuclear Fusionen
dcterms.bibliographicCitation.originalpublishernameIOPen
dcterms.bibliographicCitation.originalpublisherplaceBristolen
dcterms.bibliographicCitation.volume60en
tub.accessrights.dnbfreeen
tub.affiliationFak. 2 Mathematik und Naturwissenschaften::Zentrum für Astronomie und Astrophysikde
tub.affiliation.facultyFak. 2 Mathematik und Naturwissenschaftende
tub.affiliation.instituteZentrum für Astronomie und Astrophysikde
tub.publisher.universityorinstitutionTechnische Universität Berlinen

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