[Table of Contents]

Plasma and Fusion Research

Volume 3, S1004 (2008)

Regular Articles

Effect of Rotational Transform and Magnetic Shear on Confinement of Stellarators
Enrique ASCASÍBAR, Daniel LÓPEZ-BRUNA, Francisco CASTEJÓN, Víctor I. VARGAS, Víctor TRIBALDOS, Henning MAASSBERG1), Craig D. BEIDLER1), Rudolf BRAKEL1), Andreas DINKLAGE1), Joachim GEIGER1), Jeffrey H. HARRIS2,3), Andreas KUS1), Tohru MIZUUCHI4), Sadayoshi MURAKAMI4), Shoichi OKAMURA5), Roland PREUSS1), Fumimichi SANO4), Ulrich STROTH6), Yasuhiro SUZUKI5), Joseph TALMADGE7), Yuri TURKIN3), Kiyomasa Y. WATANABE5), Hiroshi YAMADA5) and Masayuki YOKOYAMA5)
CIEMAT, Madrid 28040, Spain
1)
Max-Planck-Institut für Plasmaphysik, EURATOM Association, Greifswald 17491, Germany
2)
Oak Ridge National Laboratory, Oak Ridge, TN 37831-6169, USA
3)
Australian National University, Canberra ACT 0200, Australia
4)
Kyoto University, Uji 611-0011, Japan
5)
National Institute for Fusion Science, Toki 509-5292, Japan
6)
Institut für Plasmaforschung, Universität Stuttgart, Stuttgart 70569, Germany
7)
University of Wisconsin, Madison, WI 53706-1481, USA
(Received 16 November 2007 / Accepted 15 February 2008 / Published 5 August 2008)

Abstract

This work surveys the main results concerning the effects of the rotational transform, its low order rational values and its shear on the confining properties of low shear devices. It is meant to promote further studies aimed at clarifying their role in future, reactor grade, devices. 1-D transport studies are encouraged as the effects of rotational transform on confinement appear to be of local nature. Low order rational values of the rotational transform are associated with both degraded and improved confinement, being the magnetic shear a plausible cause for the difference. Very small shear values are enough to avoid deletereous effects of the low order rationals in high rotational transform discharges, but further experiments are needed to elucidate whether there is a threshold shear that depends on the rotational transform itself.

Keywords

stellarator, heliotron, rotational transform, magnetic shear, confinement

DOI: 10.1585/pfr.3.S1004

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This paper may be cited as follows:

Enrique ASCASÍBAR, Daniel LÓPEZ-BRUNA, Francisco CASTEJÓN, Víctor I. VARGAS, Víctor TRIBALDOS, Henning MAASSBERG, Craig D. BEIDLER, Rudolf BRAKEL, Andreas DINKLAGE, Joachim GEIGER, Jeffrey H. HARRIS, Andreas KUS, Tohru MIZUUCHI, Sadayoshi MURAKAMI, Shoichi OKAMURA, Roland PREUSS, Fumimichi SANO, Ulrich STROTH, Yasuhiro SUZUKI, Joseph TALMADGE, Yuri TURKIN, Kiyomasa Y. WATANABE, Hiroshi YAMADA and Masayuki YOKOYAMA, Plasma Fusion Res. 3, S1004 (2008).