Bootstrap current control studies in the Wendelstein 7-X stellarator using the free-plasma-boundary version of the SIESTA MHD equilibrium code

dc.affiliation.dptoUC3M. Departamento de Físicaes
dc.affiliation.grupoinvUC3M. Grupo de Investigación: Física de Plasmases
dc.contributor.authorPeraza Rodríguez, Hugo Alberto
dc.contributor.authorReynolds Barredo, José Miguel
dc.contributor.authorSánchez Fernández, Luis Raúl
dc.contributor.authorTribaldos Macía, Víctor
dc.contributor.authorGeiger, John F.
dc.contributor.funderMinisterio de Economía y Competitividad (España)es
dc.contributor.funderUniversidad Carlos III de Madrides
dc.description.abstractThe recently developed free-plasma-boundary version of the SIESTA MHD equilibrium code (Hirshman et al 2011 Phys. Plasmas 18 062504; Peraza-Rodriguez et al 2017 Phys. Plasmas 24 082516) is used for the first time to study scenarios with considerable bootstrap currents for the Wendelstein 7-X (W7-X) stellarator. Bootstrap currents in the range of tens of kAs can lead to the formation of unwanted magnetic island chains or stochastic regions within the plasma and alter the boundary rotational transform due to the small shear in W7-X. The latter issue is of relevance since the island divertor operation of W7-X relies on a proper positioning of magnetic island chains at the plasma edge to control the particle and energy exhaust towards the divertor plates. Two scenarios are examined with the new free-plasma-boundary capabilities of SIESTA: a freely evolving bootstrap current one that illustrates the difficulties arising from the dislocation of the boundary islands, and a second one in which off-axis electron cyclotron current drive (ECCD) is applied to compensate the effects of the bootstrap current and keep the island divertor configuration intact. SIESTA finds that off-axis ECCD is indeed able to keep the location and phase of the edge magnetic island chain unchanged, but it may also lead to an undesired stochastization of parts of the confined plasma if the EC deposition radial profile becomes too narrow.en
dc.description.sponsorshipResearch was funded in part by the Spanish National Project No. ENE2015-68265. Research carried in part at the Max-PlanckInstitute for Plasma Physics in Greifswald (Germany), whose hospitality is gratefully acknowledged. SIESTA free-boundary runs have been carried out in Uranus, a supercomputer cluster located at Universidad Carlos III de Madrid and funded jointly by EU-FEDER funds and by the Spanish Government via the National Projects No. UNC313-4E-2361, No. ENE2009-12213- C03-03, No. ENE2012-33219, and No. ENE2012-31753.en
dc.identifier.bibliographicCitationPeraza-Rodriguez, H., Reynolds-Barredo, J. M., Sanchez, R., Tribaldos, V., & Geiger, J. (2018). Bootstrap current control studies in the Wendelstein 7-X stellarator using the free-plasma-boundary version of the SIESTA MHD equilibrium code. In Plasma Physics and Controlled Fusion, 60(2), 025023-025032en
dc.identifier.publicationtitlePLASMA PHYSICS AND CONTROLLED FUSIONen
dc.publisherIOP Publishingen
dc.relation.projectIDGobierno de España. ENE2009-12213-C03-03es
dc.relation.projectIDGobierno de España. ENE2012-33219es
dc.relation.projectIDGobierno de España. ENE2012-31753es
dc.relation.projectIDIndefinido. UNC313-4E-2361es
dc.relation.projectIDGobierno de España. ENE2015-68265-Pes
dc.rights© 2018 IOP Publishing Ltden
dc.rightsAtribución-NoComercial-SinDerivadas 3.0 España*
dc.rights.accessRightsopen accessen
dc.subject.otherIdeal mhden
dc.subject.otherWendelstein 7-Xen
dc.subject.otherMagnetic islandsen
dc.titleBootstrap current control studies in the Wendelstein 7-X stellarator using the free-plasma-boundary version of the SIESTA MHD equilibrium codeen
dc.typeresearch article*
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