Zonal flow sawteeth and the time period between edgelocalized transport bursts in tokamaks
Abstract
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 electronion 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 welldefined 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.
 Authors:
 Institute for Research in Electronics and Applied Physics University of Maryland, College Park, Maryland 20742 (United States)
 Publication Date:
 OSTI Identifier:
 20960091
 Resource Type:
 Journal Article
 Resource Relation:
 Journal Name: Physics of Plasmas; Journal Volume: 14; Journal Issue: 1; Other Information: DOI: 10.1063/1.2424560; (c) 2007 American Institute of Physics; Country of input: International Atomic Energy Agency (IAEA)
 Country of Publication:
 United States
 Language:
 English
 Subject:
 70 PLASMA PHYSICS AND FUSION TECHNOLOGY; BALLOONING INSTABILITY; BOUNDARY LAYERS; CYCLOTRON FREQUENCY; DENSITY; ELECTRONION COLLISIONS; ELECTRONS; IONS; NONLINEAR PROBLEMS; PLASMA; PLASMA CONFINEMENT; PLASMA DENSITY; PLASMA DIAMAGNETISM; PLASMA SIMULATION; SAFETY; SAWTOOTH OSCILLATIONS; TOKAMAK DEVICES; TURBULENCE; VELOCITY
Citation Formats
Kleva, Robert G., and Guzdar, Parvez N. Zonal flow sawteeth and the time period between edgelocalized transport bursts in tokamaks. United States: N. p., 2007.
Web. doi:10.1063/1.2424560.
Kleva, Robert G., & Guzdar, Parvez N. Zonal flow sawteeth and the time period between edgelocalized transport bursts in tokamaks. United States. doi:10.1063/1.2424560.
Kleva, Robert G., and Guzdar, Parvez N. Mon .
"Zonal flow sawteeth and the time period between edgelocalized transport bursts in tokamaks". United States.
doi:10.1063/1.2424560.
@article{osti_20960091,
title = {Zonal flow sawteeth and the time period between edgelocalized transport bursts in tokamaks},
author = {Kleva, Robert G. and Guzdar, Parvez N.},
abstractNote = {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 electronion 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 welldefined 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.},
doi = {10.1063/1.2424560},
journal = {Physics of Plasmas},
number = 1,
volume = 14,
place = {United States},
year = {Mon Jan 15 00:00:00 EST 2007},
month = {Mon Jan 15 00:00:00 EST 2007}
}

The character of particle and energy transport in simulations of tokamak edge turbulence is determined by the magnitude of the density gradient. Edge turbulence becomes increasingly intermittent as the edge density gradient increases. Beyond a critical limit in the edge density gradient, the transport is dominated by short, repetitive bursts of particles and energy outward toward the wall. These bursts are extremely ballooning in character, strongly localized on the large major radius side of the torus. The duration of a burst is given by the ballooning mode growth time t{sub 0}=(RL{sub n}){sup 1/2}/c{sub s}, where c{sub s} is the soundmore »

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