Comparison of particle transport in the scrape-off layer plasmas of Alcator C-Mod and DIII-D

Lipschultz, B.; Whyte, D.G.; LaBombard, B.

doi:10.1088/0741-3335/47/10/001

Cited by 67 publications

(117 citation statements)

References 39 publications

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“…Comparisons between DIII-D and C-Mod yield the same trends [101]. The opacity of the far SOL to neutral penetration may offer part of the explanation for the appearance of a shoulder [101]; if wall-recycled neutrals ionise in the far SOL, they are rapidly transported back to the wall as ions.…”

Section: Particle Transport In the Solmentioning

confidence: 66%

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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: Particle Transport In the Solmentioning

confidence: 66%

“…The abovementioned comparisons between C-Mod, DIII-D, and JET shows SOL profiles (including D eff and v eff ) that are similar in shape and magnitude when scaled according to dimensionless plasma physics parameters [100,101]. In particular, v eff is found to have a weak dependence on those dimensionless parameters.…”

Section: Particle Transport In the Solmentioning

confidence: 99%

Chapter 4: Power and particle control

Loarte¹,

et al. 2007

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“…Several experiments have shown evidence of density profile flattening at high Greenwald fraction, f G n=n G , or low plasma current I p . These include C-Mod, 27,28,264 DIII-D 24,264 and TCV. 52,93 In each case, the density profile becomes increasingly flat, and the density at the wall increases, as a function of f G or 1/I p .…”

Section: Experimental Evidence For Collisionality Dependencementioning

confidence: 99%

“…Ref. 264 describes a series of dimensionless scaling experiments on C-Mod and DIII-D showing that the SOL transport is very similar in the two machines. When profiles of v eff ðxÞ were plotted for collisionalities spanning an order of magnitude on C-Mod, it was found that v eff increased with collisionality near the separatrix, consistent with earlier work, 28,265 but was insensitive to collisionality near the wall.…”

Section: Experimental Evidence For Collisionality Dependencementioning

confidence: 99%

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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“…This approach was justified by experimental findings in Alcator C-mod [Lipschultz_PPCF05] and DIII-D [Whyte_PPCF05,Rudakov_NF05] that showed significant interaction of the plasma with the main chamber walls occurs in high plasma density operations. In these experiments, the 13 CH 4…”

Section: Introductionmentioning

confidence: 99%

Scrape-off layer transport and deposition studies in DIII-D

Groth

Allen

Boedo³

et al. 2007

Physics of Plasmas

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Trace 13 CH 4 injection experiments into the main scrape-off layer of low density L-mode and high-density H-mode plasmas have been performed in the DIII-D tokamak[Luxon_NF02] to mimic the transport and deposition of carbon arising from a main chamber sputtering source. These experiments indicated entrainment of the injected carbon in plasma flow in the main SOL, and transport toward the inner divertor. Ex-situ surface analysis showed enhanced 13 C surface concentration at the corner formed by the divertor floor and the angled target plate of the inner divertor in L-mode; in H-mode, both at the corner and along the surface bounding the private flux region inboard of the outer strike point. Interpretative modeling was made consistent with these experimental results by imposing a parallel carbon ion flow in the main SOL toward the inner target, and a radial pinch toward the separatrix. Predictive modeling carried out to better understand the underlying plasma transport processes suggests that the deuterium flow in the main SOL is related to the degree of detachment of the inner divertor leg. These simulations show that carbon ions are entrained with the deuteron flow in the main SOL via frictional coupling, but higher charge state carbon ions may be suspended upstream of the inner M. Groth et al.Scrape-off layer transport and deposition studies in DIII-D GA-A25625, DRAFT 3 APS/DPP Invited ms 2 divertor X-point region due to balance of the friction force and the ion temperature gradient.

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Comparison of particle transport in the scrape-off layer plasmas of Alcator C-Mod and DIII-D

Cited by 67 publications

References 39 publications

Chapter 4: Power and particle control

Chapter 4: Power and particle control

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

Scrape-off layer transport and deposition studies in DIII-D

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