Show simple item record

AuthorOberparleiter, Michaeldc.contributor.author
Date of accession2016-03-15T10:40:47Zdc.date.accessioned
Available in OPARU since2016-03-15T10:40:47Zdc.date.available
Year of creation2015dc.date.created
AbstractFor the application of the nuclear fusion of hydrogen as a heat source for electricity generation understanding of the magnetic fuel confinement is crucial. Most of the cross-field transport in modern-day tokamaks is carried by turbulence driven by steep pressure gradients. Background neoclassical transport, however, provides a steady level of cross-field flux even in cases when turbulence becomes weak or suppressed. The goal of this work is to quantify how neoclassical (NC) effects and turbulence can influence each other. For this purpose the nonlinear gyrokinetic turbulence code GENE is employed. Firstly, its ability to self-consistently calculate the NC radial electric field is successfully benchmarked against the radial force balance equation and NC transport in the plasma region close to the center of a tokamak is studied. In the next step a model system where a long-wavelength external potential is imposed on ion temperature gradient-driven (ITG) turbulence is investigated. It is found that the self-generated shear flow pattern of the turbulence adapts to the imposed pattern and a small external shear is sufficient to notably reduce turbulent transport. Motivated by this global ITG simulations with fixed pressure gradient profiles are performed with and without inclusion of NC effects. Their comparison reveals that the NC field enhances turbulent transport by 20-30 % for a ratio of ion gyroradius and device radius larger than 1/300. An explanation is that the NC field aligns a region of low shear with the maximum of the gradient profile where the turbulent drive is strongest. Further investigation reveals that NC effects also change the dependence of the system on collisionality or safety factor. Finally, in physically more comprehensive simulations with fixed power input and a self-consistently evolving temperature profile, the additional NC transport channel is found to reduce the frequency and amplitude of intermittent turbulent transport bursts.dc.description.abstract
Languageendc.language.iso
PublisherUniversität Ulmdc.publisher
LicenseStandarddc.rights
Link to license texthttps://oparu.uni-ulm.de/xmlui/license_v3dc.rights.uri
KeywordGyrokineticsdc.subject
KeywordGyrokinetikdc.subject
KeywordNeoclassical transportdc.subject
KeywordNeoklassischer Transportdc.subject
Dewey Decimal GroupDDC 530 / Physicsdc.subject.ddc
LCSHHot plasmasdc.subject.lcsh
LCSHNuclear fusiondc.subject.lcsh
LCSHPlasma turbulencedc.subject.lcsh
LCSHTokamaksdc.subject.lcsh
TitleInteraction between the neoclassical equilibrium and microturbulence in gyrokinetic simulationsdc.title
Resource typeDissertationdc.type
DOIhttp://dx.doi.org/10.18725/OPARU-3333dc.identifier.doi
PPN833228811dc.identifier.ppn
URNhttp://nbn-resolving.de/urn:nbn:de:bsz:289-vts-96650dc.identifier.urn
GNDHeißes Plasmadc.subject.gnd
GNDKernfusiondc.subject.gnd
GNDPlasmaphysikdc.subject.gnd
GNDTokamakdc.subject.gnd
FacultyFakultät für Naturwissenschaftenuulm.affiliationGeneral
Date of activation2015-08-05T10:49:57Zuulm.freischaltungVTS
Peer reviewneinuulm.peerReview
Shelfmark print versionW: W-H 14.313uulm.shelfmark
DCMI TypeTextuulm.typeDCMI
VTS ID9665uulm.vtsID
CategoryPublikationenuulm.category
Bibliographyuulmuulm.bibliographie


Files in this item

Thumbnail

This item appears in the following Collection(s)

Show simple item record