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abstract_w7x_radcool_effenberg.pdf2014-05-30 11:11:06Florian Effenberg

Investigation of impact of radiation cooling on startup plasmas at Wendelstein 7-X with EMC3-EIRENE simulations

Author: Florian Effenberg
Requested Type: Poster Only
Submitted: 2014-05-30 11:09:41

Co-authors: Y. Feng, S. Bozhenkov, H. Frerichs, H. Hoelbe, D. Reiter, O. Schmitz, T. S. Pedersen

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

Abstract Text:

The stellarator Wendelstein 7-X will operate in a limiter configuration in the first plasma operation phase. In this field configuration the edge does not include magnetic islands and the scrape-off layer (SOL) is defined by five poloidal graphite limiters at the toroidal symmetry planes. They have to protect the wall and metallic frame structure of target elements to be installed in later operation phases. Although the limiter configuration is based on a field structure of nearly closed flux surfaces the limiters generate a non-isotropic edge topology of poloidally varying shortest connection lengths. Exploring options to reduce the heat flux to these components is important for optimization of the performance and duration of these first plasmas.

The 3D plasma transport Monte-Carlo code EMC3-EIRENE is based on a fluid model for electrons and ions, a kinetic model for neutral particles, and a simplified fluid approach for impurity ions. Transport simulations are performed for startup plasmas taking impurities due to carbon sputtering from the limiters and active local gas injection into account. The impact on plasma transport and the reduction of heat load to plasma facing components by radiative edge cooling is investigated.

Characterization: 1.4,4.0

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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