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iter_3dmodeling_oliverschmitz-1.pdf2014-06-02 09:56:58Oliver Schmitz
iter_3dmodeling_oliverschmitz.pdf2014-06-02 09:54:10Oliver Schmitz

Modeling of plasma edge transport and divertor fluxes with three-dimensional magnetic control fields applied for ELM control at ITER

Author: Oliver Schmitz
Requested Type: Consider for Invited
Submitted: 2014-06-02 09:55:34

Co-authors: M.Becoulet, P. Cahyna, T.E.Evans, Y. Feng, N.A. Ferraro, H. Frerichs, A. Kischner, A.Kukushkin, T.Lunt, A.Loarte, R.Pitts, D. Reiser, D. Reiter, G. Saibene, U.Samm, S.Wiesen

Contact Info:
University of Wisconsin - Madison, Department of E
1500 Engineering Drive
Madison, Wisconsin   53706
USA

Abstract Text:
A set of in-vessel magnetic control coils is planned for control of type-I edge localized modes (ELMs) by resonant magnetic perturbation (RMP) fields at ITER. During RMP ELM control formation of a three-dimensional plasma boundary was measured on several devices. The plasma wall interaction is transformed from axisymmetry into a 3D situation. In this contribution results from 3D plasma fluid transport and kinetic neutral transport modeling with the EMC3-Eirene code are shown and they are directly related to experimental observations. Particular emphasis is put to the relation between the internal plasma response and the shape and geometry of the 3-D boundary structure. A sequence of four perturbed magnetic topologies is addressed in EMC3-Eirene modeling.

Overlapping helical lobes at the separatrix are formed by the invariant manifolds of the hyperbolic fixed point (divertor X-point). They yield generation of helical magnetic flux bundles with short magnetic connection length from inside the separatrix to the divertor target. This represents the new, 3D helical scrape off layer, which intersects the divertor target in a helical, striated magnetic footprint. It is shown that the 3D SOL channels enhance the outward particle transport even if a strong internal shielding of the RMP field is considered. Their existence result in increased convective particle flows towards the target and the level of sonic flow depends on the divertor recycling. The formation of striated heat and particle flux patterns in nowadays experiments supports the existence of these 3D SOL channels and hence such a strong impact on the particle transport. The modeling results show that this mechanism also perturbs the particle balance at ITER. However, we find that the level of density pump out born from these flux channels can be compensated by an increase in the pellet fueling leveling to about 50% of the actual pellet fueling capability of ITER.

Characterization: 1.4

Comments:

Workshop on Exploratory Topics in Plasma and Fusion Research (EPR) and US-Japan Compact Torus (CT) Workshop
August 5-8, 2014
Madison, Wisconsin

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