Theoretical analysis of the influence of external biasing on long range turbulent transport in the scrape-off layer

Ghendrih, Ph.; Sarazin, Y.; Attuel, Guillaume; Benkadda, S.; Beyer, Peter; Falchetto, G.; Figarella, C.; Garbet, X.; Grandgirard, V.; Ottaviani, M.

doi:10.1088/0029-5515/43/10/001

Cited by 76 publications

(63 citation statements)

References 25 publications

(31 reference statements)

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“…In such a regime, the turbulent particle flux is found to be strongly intermittent. Density fronts propagate ballistically [591,593,594,595] and a large fraction of the total particle flux is transported by rare and large transport events [596]. In these simulations, no scale separation is found between the smallest density gradient scale, typically ~ ρ s , the mean density gradient ~ 55 ρ s and the long range ballistic propagation of a given density front ~ 200 ρ s .…”

Section: Present Modelling Effort Of Cross-field Turbulencementioning

confidence: 92%

Chapter 4: Power and particle control

Loarte¹,

et al. 2007

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Abstract.Progress, since the ITER Physics Basis publication, in understanding the processes that will determine the properties of the plasma edge and its interaction with material elements in ITER is described. Experimental areas where significant progress has taken place are : energy transport in the SOL in particular of the anomalous transport scaling, particle transport in the SOL that plays a major role in the interaction of diverted plasmas with the main chamber material elements, ELM energy deposition on material elements and the transport mechanism for the ELM energy from the main plasma to the plasma facing components, the physics of plasma detachment and neutral dynamics including the edge density profile structure and the control of plasma particle content and He removal, the erosion of low and high Z materials in fusion devices, their transport to the core plasma and their migration at the plasma edge including the formation of mixed materials, the processes determining the size and location of the retention of tritium in fusion devices and methods to remove it and the processes determining the efficiency of the various fuelling methods as well as their development towards the ITER requirements. This experimental progress has been accompanied by the development of modelling tools for the physical processes at the edge plasma and plasma-materials interaction and the further validation of these models by comparing their predictions with the new experimental results. Progress in the modelling development and validation has been mostly concentrated in the following areas : refinement of the predictions for ITER with plasma edge modelling codes by inclusion of detailed geometrical features of the divertor and the introduction of physical effects, which can play a 2 major role in determining the divertor parameters at the divertor for ITER conditions such as hydrogen radiation transport and neutral-neutral collisions, modelling of the ion orbits at the plasma edge, which can play a role in determining power deposition at the divertor target, models for plasma-materials and plasma dynamics interaction during ELMs and disruptions, models for the transport of impurities at the plasma edge to describe the core contamination by impurities and the migration of eroded materials at the edge plasma and its associated tritium retention and models for the turbulent processes that determine the anomalous transport of energy and particles across the SOL. The implications for the expected performance of the reference regimes in ITER, the operation of the ITER device and the lifetime of the plasma facing materials are discussed. Introduction.This chapter outlines the significant progress achieved since the ITER Physics Basis in understanding basic scrape-off layer (SOL) and divertor processes in a tokamak. The interaction of plasma with first-wall surfaces will have considerable impact on the performance of fusion plasmas, the lifetime of plasma facing components, and the retention of tritium in next step Burning Plasma E...

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Section: Present Modelling Effort Of Cross-field Turbulencementioning

confidence: 92%

Chapter 4: Power and particle control

Loarte¹,

et al. 2007

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“…(1) and (2). An example with a sheath closure for J jj and curvature drive for the force term 79 is shown in Fig. 4.…”

Section: E Statistical Evidence For Blobs and Holesmentioning

confidence: 99%

“…37,69,79 For nonspinning blobs, sheared flow was shown to inhibit radial transport, 16,37 but for spinning blobs the effect depends on the direction of the sheared flow relative to that of the blob spin. 69 In theory, sheared flow also affects the rate of blob formation by controlling the strength of the edge turbulence (see Sec.…”

Section: Of Ref 40)mentioning

confidence: 99%

“…The effect of strong sheared-flow layers (produced by biasing) was studied by theory, simulations and experiments in several papers; 37,69,79,216 this work gives a qualitative picture of the effect of the self-generated flows in the H-mode. These simulations show that the effect of sheared poloidal flows is to strongly suppress the blob transport across the shear layer.…”

Section: Strong Sheared Flows: Blobs (H-mode)mentioning

confidence: 99%

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Convective transport by intermittent blob-filaments: Comparison of theory and experiment

2011

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A blob-filament (or simply “blob”) is a magnetic-field-aligned plasma structure which is considerably denser than the surrounding background plasma and highly localized in the directions perpendicular to the equilibrium magnetic field B. In experiments and simulations, these intermittent filaments are often formed near the boundary between open and closed field lines, and seem to arise in theory from the saturation process for the dominant edge instabilities and turbulence. Blobs become charge-polarized under the action of an external force which causes unequal drifts on ions and electrons; the resulting polarization-induced E × B drift moves the blobs radially outwards across the scrape-off-layer (SOL). Since confined plasmas generally are subject to radial or outwards expansion forces (e.g., curvature and ∇B forces in toroidal plasmas), blob transport is a general phenomenon occurring in nearly all plasmas. This paper reviews the relationship between the experimental and theoretical results on blob formation, dynamics and transport and assesses the degree to which blob theory and simulations can be compared and validated against experiments.

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“…First results on the latter topic have been obtained in [60,7,61], but as turbulence has significantly more degrees of freedom than lowdimensional chaotic systems, new efficient control schemes have to be developed.…”

Section: Challenges To Modeling and Simulationmentioning

confidence: 99%

Turbulent transport and the plasma edge

Naulin¹

2007

Journal of Nuclear Materials

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Theoretical analysis of the influence of external biasing on long range turbulent transport in the scrape-off layer

Cited by 76 publications

References 25 publications

Chapter 4: Power and particle control

Chapter 4: Power and particle control

Convective transport by intermittent blob-filaments: Comparison of theory and experiment

Turbulent transport and the plasma edge

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