Suppression of vertical instability in elongated current-carrying plasmas by applying stellarator rotational transform

Journal Article · Thu May 15 00:00:00 EDT 2014 · Physics of Plasmas

DOI:https://doi.org/10.1063/1.4878615· OSTI ID:22300206

ArchMiller, M. C.; Cianciosa, M. R.; Ennis, D. A.; Hanson, J. D.; Hartwell, G. J.; Hebert, J. D.; Herfindal, J. L.; Knowlton, S. F.; Ma, X.; Maurer, D. A.; Pandya, M. D.; Traverso, P. ^[1]

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1. Physics Department, Auburn University, Auburn, Alabama 36849 (United States)

The passive stability of vertically elongated current-carrying toroidal plasmas has been investigated in the Compact Toroidal Hybrid, a stellarator/tokamak hybrid device. In this experiment, the fractional transform f, defined as the ratio of the imposed external rotational transform from stellarator coils to the total rotational transform, was varied from 0.04 to 0.50, and the elongation κ was varied from 1.4 to 2.2. Plasmas that were vertically unstable were evidenced by motion of the plasma in the vertical direction. Vertical drifts are measured with a set of poloidal field pickup coils. A three chord horizontally viewing interferometer and a soft X-ray diode array confirmed the drifts. Plasmas with low fractional transform and high elongation are the most susceptible to vertical instability, consistent with analytic predictions that the vertical mode in elongated plasmas can be stabilized by the poloidal field of a relatively weak stellarator equilibrium.

• OSTI ID: 22300206
• Journal Information: Physics of Plasmas, Vol. 21, Issue 5; Other Information: (c) 2014 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA); ISSN 1070-664X
• Country of Publication: United States
• Language: English

Related Subjects

70 PLASMA PHYSICS AND FUSION TECHNOLOGY
CURRENTS
ELONGATION
HYBRIDIZATION
PLASMA DRIFT
PLASMA INSTABILITY
ROTATIONAL TRANSFORM
SOFT X RADIATION
STABILITY
TOKAMAK DEVICES