Local measurements of tearing mode flows and the magnetohydrodynamic dynamo in the Madison Symmetric Torus reversed-field pinch

Journal Article · Sun Aug 15 00:00:00 EDT 2010 · Physics of Plasmas

DOI:https://doi.org/10.1063/1.3458667· OSTI ID:21432198

Ennis, D A; Gangadhara, S; Den Hartog, D J; Ebrahimi, F; Fiksel, G; Prager, S C ^[1]; Craig, D ^[2]; Anderson, J K ^[1]

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1. University of Wisconsin-Madison, Madison, Wisconsin 53706-1390 (United States)
2. Wheaton College, Wheaton, Illinois 60187-5501 (United States)

The first localized measurements of tearing mode flows in the core of a hot plasma are presented using nonperturbing measurements of the impurity ion flow. Emission from charge exchange recombination is collected by a novel high optical throughput duo spectrometer providing localized ({+-}1 cm) measurements of C{sup +6} impurity ion velocities resolved to <500 m/s with high bandwidth (100 kHz). Poloidal tearing mode flows in the Madison Symmetric Torus reversed-field pinch are observed to be localized to the mode resonant surface with a radial extent much broader than predicted by linear magnetohydrodynamic (MHD) theory but comparable to the magnetic island width. The relative poloidal flow amplitudes among the dominant core modes do not reflect the proportions of the magnetic amplitudes. The largest correlated flows are associated with modes having smaller magnetic amplitudes resonant near the midradius. The MHD dynamo due to these flows on the magnetic axis is measured to be adequate to balance the mean Ohm's law during reduced tearing activity and is significant but does not exclude other dynamo mechanisms from contributing during a surge in reconnection activity.

• OSTI ID: 21432198
• Journal Information: Physics of Plasmas, Vol. 17, Issue 8; Other Information: DOI: 10.1063/1.3458667; (c) 2010 American Institute of Physics; ISSN 1070-664X
• Country of Publication: United States
• Language: English

Related Subjects

70 PLASMA PHYSICS AND FUSION TECHNOLOGY
CHARGE EXCHANGE
HOT PLASMA
MAGNETIC ISLANDS
MAGNETOHYDRODYNAMICS
PLASMA IMPURITIES
RECOMBINATION
REVERSE-FIELD PINCH
TEARING INSTABILITY
FLUID MECHANICS
HYDRODYNAMICS
IMPURITIES
INSTABILITY
MAGNETIC FIELD CONFIGURATIONS
MECHANICS
PINCH EFFECT
PLASMA
PLASMA INSTABILITY
PLASMA MACROINSTABILITIES