Forschungszentrum Jülich, Zentralbibliothek
Three-dimensional plasma transport in open chaotic magnetic fields : a computational assessment for tokamak edge layers
Abstract
dc:descriptionThe development of nuclear fusion as an alternative energy source requires the research on magnetically confined, high temperature plasmas. In particular, the quantification of plasma flows in the domain near exposed material surfaces of the plasma container by computer simulations is of key importance, both for guiding interpretation of present fusion experiments and for aiding the ongoing design activities for large future devices such as ITER, W7-X or the DEMO reactor. There is a large number of computational issues related to the physics of hot, fully ionized and magnetized plasmas near surfaces of the vacuum chamber. This thesis is dedicated to one particular such challenge, namely the numerical quantification of self-consistent kinetic neutral gas and plasma fluid flows in very complex 3D (partially chaotic) magnetic fields, in the absence of any common symmetries for plasma and neutral gas dynamics. Such magnetic field configurations are e.g. generated by externally applied magnetic perturbations at the plasma edge, and are of great interest for the control of particle and energy exhausts. In the present thesis the 3D edge plasma and neutral particle transport code EMC3-EIRENE is applied to two distinct configurations of open chaotic magnetic system: at the TEXTOR and DIII-D tokamaks. Improvements of the edge transport model and extensions of the transport code are presented, which have allowed such simulations for the first time for 3D scenarios at DIII-D with ITER similar plasmas. A strong 3D effect of the chaotic magnetic field on the DIII-D edge plasma is found and analyzed in detail. It is found that a pronounced striation pattern of target particle and heat fluxes at DIII-D can only be obtained up to a certain upper limiting level of anomalous cross-field transport. Hence, in comparison to experimental data, these findings allow to narrow down the range of this model parameter. One particular interest at TEXTOR is the achievement of a regime with reduced particle and heat fluxes towards the divertor target within a 3D perturbed boundary, the so called helical divertor configuration. It is shown in this thesis that plasma states, which are both consistent with the limited experimental data and show transition to reduced particle and heat fluxes, can indeed be observed in numerical simulations of the TEXTOR helical divertor. This is, however, at the expense of also reduced upstream temperatures, which might not be consistent with an advanced tokamak operation (in which the hottest possible confined plasma periphery should be combined with the coldest possible plasma-wall contact zone).
Degree
thesis:*- Grantor dc:publisher
- Forschungszentrum Jülich, Zentralbibliothek
- Year dc:date
- 2009
Author and committee
dc:creator, dc:contributor.*- Author dc:creator
-
- Frerichs, Heinke Gerd
- Contributors dc:contributor
-
- Kull, Hans-Jörg
Subjects
dc:subject × 11Rights
dc:rights- Statement dc:rights
-
- info:eu-repo/semantics/openAccess
- Language dc:language
- eng