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Physics of Plasmas -- May 2000 -- Volume 7, Issue 5 pp. 1809-1815

Magnetohydrodynamics stability of compact stellarators

G. Y. Fu and L. P. Ku

Princeton Plasma Physics Laboratory, Princeton, New Jersey 08543

W. A. Cooper

CRPP, EPFL, Lausanne, Switzerland

S. H. Hirshman

Oak Ridge National Laboratory, Oak Ridge, Tennessee 37830

D. A. Monticello, M. H. Redi, and A. Reiman

Princeton Plasma Physics Laboratory, Princeton, New Jersey 08543

R. Sanchez

Universidad Carlos III de Madrid, Madrid, Spain

D. A. Spong

Oak Ridge National Laboratory, Oak Ridge, Tennessee 37830

(Received 16 November 1999; accepted 30 December 1999)

Recent stability results of external kink modes and vertical modes in compact stellarators are presented. The vertical mode is found to be stabilized by externally generated poloidal flux. A simple stability criterion is derived in the limit of large aspect ratio and constant current density. For a wall at infinite distance from the plasma, the amount of external flux needed for stabilization is given by F_i = (²–)/(² + 1), where is the axisymmetric elongation and F_i is the fraction of the external rotational transform. A systematic parameter study shows that the external kink mode in a quasiaxisymmetric stellarator (QAS) can be stabilized at high beta (~5%) without a conducting wall by magnetic shear via three-dimensional (3D) shaping. It is found that external kinks are driven by both parallel current and pressure gradient. The pressure contributes significantly to the overall drive through the curvature term and the Pfirsch–Schluter current. ©2000 American Institute of Physics.

PII: S1070-664X(00)91005-X
DOI: 10.1063/1.874002
PACS: 52.55.Hc, 52.30.-q, 52.35.Py, 52.35.Qz, 52.25.Kn        Additional Information

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Citing Articles

1. Recent advances in the design of quasiaxisymmetric stellarator plasma configurations
   A. Reiman et al., Phys. Plasmas 8, 2083 (2001)
2. Physics issues in the design of high-beta, low-aspect-ratio stellarator experiments
   G. H. Neilson et al., Phys. Plasmas 7, 1911 (2000)