Zonal flow sawteeth and the time period between edge-localized transport bursts in tokamaks

Journal Article · Mon Jan 15 00:00:00 EST 2007 · Physics of Plasmas

DOI:https://doi.org/10.1063/1.2424560· OSTI ID:20960091

Kleva, Robert G; Guzdar, Parvez N ^[1]

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1. Institute for Research in Electronics and Applied Physics University of Maryland, College Park, Maryland 20742 (United States)

The time period between particle and energy transport bursts in simulations of tokamak edge turbulence is determined by the magnitude of the diamagnetic drift parameter {alpha}{sub d}{identical_to}{omega}{sub *}/{gamma}{sub 0}, where the diamagnetic drift frequency {omega}{sub *}={rho}{sub s}c{sub s}/L{sub 0}L{sub n} and the characteristic ballooning mode growth rate {gamma}{sub 0}=c{sub s}/(RL{sub n}/2){sup 1/2}. Here, R is the major radius of the torus, L{sub n} is the density gradient scale length, {rho}{sub s} is the ion gyroradius, and c{sub s} is the ion acoustic speed. The scale length L{sub 0} is given by L{sub 0}=2{pi}qR {nu}{sub ei}{rho}{sub s}/2{omega}{sub e}R){sup 1/2}(2R/L{sub n}){sup 1/4}, where q is the safety factor, {nu}{sub ei} is the electron-ion collision frequency, and {omega}{sub e} is the electron cyclotron frequency. When the diamagnetic drift frequency becomes larger than the ballooning mode growth rate ({alpha}{sub d}>1), then the transport in the tokamak edge is characterized by regularly recurring bursts of particles and energy with a single well-defined frequency. As {alpha}{sub d} increases above unity, the time period between the bursts becomes much longer. The temporal dependence of the energy in the zonal flow generated nonlinearly has the appearance of sawteeth.

• OSTI ID: 20960091
• Journal Information: Physics of Plasmas, Vol. 14, Issue 1; Other Information: DOI: 10.1063/1.2424560; (c) 2007 American Institute of Physics; 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
BALLOONING INSTABILITY
BOUNDARY LAYERS
CYCLOTRON FREQUENCY
DENSITY
ELECTRON-ION COLLISIONS
ELECTRONS
IONS
NONLINEAR PROBLEMS
PLASMA
PLASMA CONFINEMENT
PLASMA DENSITY
PLASMA DIAMAGNETISM
PLASMA SIMULATION
SAFETY
SAWTOOTH OSCILLATIONS
TOKAMAK DEVICES
TURBULENCE
VELOCITY