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stephey_epr_abstract.pdf2014-05-29 12:10:05Laurie Stephey

Exploration of neutral and impurity exhaust in the HSX stellarator by a pumped limiter

Author: Laurie A Stephey
Requested Type: Poster Only
Submitted: 2014-05-29 12:09:11

Co-authors: A. Akerson, A. Bader, O. Schmitz, D. T. Anderson, F. S. B. Anderson, J. N. Talmadge, C. Hegna

Contact Info:
University of Wisconsin- Madison
1415 Engineering Drive
Madison, Wisconsin   53706
USA

Abstract Text:
A preliminary study of neutral recycling and plasma fueling will be attempted using a pumped limiter in HSX to concentrate the plasma source. This limiter will have significant pumping capability to remove the neutrals and gain control of the plasma source. In order to eliminate the sourcing uncertainties in a hydrogen plasma, helium plasmas, with full recycling and a negligible wall sink, will be used. Additionally, core fueling by Franck-Condon atoms should be reduced. These experimental tools to explore control methods of the neutral source in HSX will be used to develop and expand a single reservoir particle balance model to determine a complete balance of sources and sinks in the HSX device. Neutral line emission filtered images can be used to measure the particle flux at the limiter. IR images of the limiter, along with the THEODOR code [1], will be used to calculate the heat flux to the limiter. These measurements of density, temperature, and fueling at the limiter will be combined with upstream Langmuir probe measurements [2] to diagnose the regime of operation (i.e., sheath-limited, high-recycling, or detached) that is created by the pumped limiter. These results will be qualitatively compared to recent simulations on HSX [3] using the coupled codes EMC3-EIRENE [4] and will provide insight into the applicability of the simple and complex SOL models to the 3D HSX edge. [1] A. Hermann. "Limitations for divertor heat flux calculations of fast events in tokamaks." 28th EPS Conference on Controlled Fusion and Plasma Physics, 2001. [2] A. Akerson et al. "Investigation of perpendicular and parallel transport in the edge of HSX stellarator and comparisons with EMC3-EIRENE". EPR poster, 2014. [3] A. Bader et al. "Simulations of edge configurations in quasi-helically symmetric geometry using EMC3-EIRENE". J. Nucl. Fusion. Vol. 53, No. 11, 2013. [4] Y. Feng et al. "3D edge modeling and island divertor physics." Contrb. Plasma Physics. 44 (2004).

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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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