TEXT tokamak edge turbulence modeling

Leboeuf, J. N.; Lee, Dae Keun; Carreras, B. A.; Domínguez, N.; Harris, J. H.; Hedrick, C.L.; Hidalgo, C.; Holmes, J. A.; Ruiter, J.R.; Diamond, P. H.; Ware, A. S.; Ritz, Ch. P.; Wootton, A. J.; Rowan, W. L.; Bravenec, R. V.

doi:10.1063/1.859596

Cited by 50 publications

(12 citation statements)

References 7 publications

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“…Ionization-driven drift wave instabilities have been considered as potential candidates to explain inward-directed particle fluxes [34]. Though ionization in the H-1 occurs in the inner plasma regions [22], introducing a potential drive for the ionization drift waves, there are several counter arguments.…”

Section: Discussionmentioning

confidence: 99%

Effect of the radial electric field on the fluctuation-produced transport in the H-1 heliac

Shats

1999

Plasma Phys. Control. Fusion

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Abstract. Highly coherent low-frequency fluctuations are studied experimentally in the low electron temperature plasma in the H-1 toroidal heliac. The fluctuations, presumably pressuregradient-driven resistive MHD modes, produce considerable radial particle transport. A build-up of strong sheared radial electric field leads to dramatic modifications in the fluctuation-driven transport. These modifications correlate with sudden changes in the plasma confinement, resembling low-tohigh transitions in other machines. Strong negative shear in the radial electric field eventually leads to the suppression of the fluctuations, while the onset of the strong positive shear correlates with the reversal of the fluctuation-driven particle flux, leading to the inward-directed pinch. It is concluded that the radial electric field modifies radial profiles of the fluctuation propagation velocity due to the Doppler shift, and it is this velocity shear which is important for the transport modifications.

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Section: Discussionmentioning

confidence: 99%

Effect of the radial electric field on the fluctuation-produced transport in the H-1 heliac

Shats

1999

Plasma Phys. Control. Fusion

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“…38 The question of the role of low-q surfaces in confinement has a long history. [39][40][41][42][43] Low-q surfaces have in the past been associated with microtearing modes, magnetic islands of unexplained origin, etc., all with the aim of providing a physical basis for the notion of profile consistency. Previous work 44 has also suggested that spikes or humps in the fluctuation intensity profile may sit at low-q resonances, and that these localized intensity gradients may drive sheared poloidal flow via the Reynolds stress.…”

Section: ͑49͒mentioning

confidence: 99%

Multiscale interaction of a tearing mode with drift wave turbulence: A minimal self-consistent model

McDevitt

Diamond

2006

Physics of Plasmas

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A minimal self-consistent model of the multiscale interaction of a tearing mode with drift wave turbulence is presented. A tearing instability in a cylindrical plasma interacting with electrostatic drift waves is considered, for reasons of simplicity. Wave kinetics and adiabatic theory are used to treat the feedback of tearing mode flows on the drift waves via shearing and radial advection. The stresses exerted by the self-consistently evolved drift wave population density on the tearing mode are calculated by mean field methods. The principal effect of the drift waves is to pump the resonant low-m mode via a negative viscosity, consistent with the classical notion of an inverse cascade in quasi-two-dimensional turbulence. This process can occur alone or in synergy with current gradient drive of the low-m mode. Speculations of the relation of this multiscale process to the more general issue of the fate of energy transferred to large scales by an inverse cascade are presented. The existence of nonlinearly driven vortices pinned to low-q surfaces as a class of highly anisotropic dissipative structures which terminate the inverse cascade is proposed. The evolution of a finite size magnetic island is discussed.

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“…There is experimental evidence showing that the induced turbulent transpon can account for most of the particle transport in the edge región of the plasma in tokamaks and stellarators [1,2]. However, although our understanding of the plasma turbulence has been improved during the last few years, the dominant free energy source responsible for the turbulence (Vn, VT, VZ,...) has not been identified yet [3,4].…”

mentioning

confidence: 99%

“…In the present experiments, plasmas have been obtained using electron cyclotron heating (ECH). Discharges with PECH = 200-400 kW, & J (4)(5)(6) x 10" ~m -~, stored energy SE = 1-2 kJ and magnetic field B = 1 T have been studied. Plasma edge turbulence has been characterized by means of Langmuir probes using the experimental methods described previously [2, 61.…”

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confidence: 99%

Experimental evidence of edge turbulence driven by multiple mechanisms in ATF

et al. 1993

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The scaling properties of edge fluctuations have been investigated using Langmuir probes in the edge región of the Advanced Toroidal Facility (ATF). Fluctuations in the ion saturation current (Is/Is) and transpon inferred from the fluctuations increase with increasing density gradient, while keeping unchanged local electrón temperature. The modificatíon of the electrón temperature in the range (10-50) eV, keeping constant the density profile, does not have any significant influence on I s /I s. In regions were E r /B ~ 0, the poloidal phase velocity of the fluctuations is given by v p h = 2T e /L n B. More than one of any so far proposed mechanisms must be invoked to explain all the experimental observations.

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TEXT tokamak edge turbulence modeling

Cited by 50 publications

References 7 publications

Effect of the radial electric field on the fluctuation-produced transport in the H-1 heliac

Effect of the radial electric field on the fluctuation-produced transport in the H-1 heliac

Multiscale interaction of a tearing mode with drift wave turbulence: A minimal self-consistent model

Experimental evidence of edge turbulence driven by multiple mechanisms in ATF

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