Stabilization of sawteeth in tokamaks by sheared poloidal flows

Journal Article · Wed Jan 01 04:00:00 EST 1992 · Physics of Fluids B; (United States)

DOI:https://doi.org/10.1063/1.860436· OSTI ID:5550536

Kleva, R G ^[1]

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1. Laboratory for Plasma Research, University of Maryland, College Park, Maryland 20742-3511 (United States)

The resistive internal kink mode in a current profile with a central safety factor {ital q}(0){lt}1 is shown to be stabilized by sheared poloidal flows. The internal kink mode is found to be stabilized when the local gradient in the poloidal rotation frequency {omega} at the {ital q}=1 resonant surface {ital r}{sub 1} is larger than the local gradient in the shear Alfven frequency {omega}{sub A}={ital k}{sub {parallel}}({ital r}){ital V}{sub A}, where {ital V}{sub A} is the Alfven velocity and the parallel wave number {ital k}{sub {parallel}}({ital r})={ital R}{sup {minus}1}(1{minus}1/{ital q}({ital r})) with {ital R} the major radius of the torus and {ital q}({ital r}) the safety factor profile in the minor radial coordinate {ital r}; i.e., {vert bar}{ital d}{omega}/{ital dr}{vert bar}{sub {ital r}{sub 1}}{ge}{vert bar}{ital d}{omega}{sub A}/{ital dr}{vert bar}{sub {ital r}1}. The internal kink is stabilized by sub-Alfvenic flows in which the peak velocity is only a very small fraction of the Alfven velocity. When the shear in the rotation frequency at the resonant surface is too weak to linearly stabilize the internal kink mode, then the kink mode can still be nonlinearly stabilized, resulting in incomplete reconnection, if the shear in the rotation increases just outside the resonant surface at larger radii.

• OSTI ID: 5550536
• Journal Information: Physics of Fluids B; (United States), Journal Name: Physics of Fluids B; (United States) Vol. 4:1; ISSN 0899-8221; ISSN PFBPE
• Country of Publication: United States
• Language: English

Related Subjects

70 PLASMA PHYSICS AND FUSION TECHNOLOGY
700310 -- Plasma Confinement-- (1992-)
700340* -- Plasma Waves
Oscillations
& Instabilities-- (1992-)
ALFVEN WAVES
CLOSED PLASMA DEVICES
CONFIGURATION
CONFINEMENT
CURRENT DENSITY
CYLINDRICAL CONFIGURATION
FLUID MECHANICS
HYDRODYNAMICS
HYDROMAGNETIC WAVES
INSTABILITY
KINK INSTABILITY
MAGNETOHYDRODYNAMICS
MECHANICAL PROPERTIES
MECHANICS
PLASMA CONFINEMENT
PLASMA INSTABILITY
PLASMA MACROINSTABILITIES
PLASMA SIMULATION
SHEAR PROPERTIES
SIMULATION
STABILIZATION
THERMONUCLEAR DEVICES
TOKAMAK DEVICES