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On the microinstability properties of quasi-helically symmetric stellarators

Author: C C Hegna
Requested Type: Poster Only
Submitted: 2014-05-30 16:35:23

Co-authors: M. N. Rorvig

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

Abstract Text:
A forefront area of stellarator research is the use of three-dimensional shaping to optimize microinstability properties and the associated turbulent transport. In particular, recent studies have largely focused on ion temperature gradient (ITG) modes where efforts to improve the stability properties have emerged [1]. In this work, we explore ITG stability in quasi-helically symmetric (QHS) configurations. A distinguishing feature of QHS is the presence of a relatively short connection length. This has the effect on the ITG of making it more slab-like, particularly at short wavelength [2], rather the conventional toroidal driven modes present in tokamaks and quasi-axisymmetric stellararators [1]. As such, parallel dynamics play a relatively more prominent role and emphasize a different set of 3-D shaping components than are present in toroidal ITG modes.

[1] H. E. Mynick, N. Pomphrey, P.Xanthopoulos, Phys. Rev. Lett. 105, 0954004 (2010); Phys. Plasmas 18, 056101 (2011).
[2] G. G. Plunk, P. Helander, P. Xanthopoulos and J. W. Connor, Phys. Plasmas 21, 032112 (2014).

* Research supported by U. S. DoE under grant nos. DE-FG02-99ER54546 and DE-SC0006103.

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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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