EDGE2D code simulations of SOL flows and in–out divertor asymmetries in JET

Kirnev, G.; Corrigan, G.; Coster, D.; Erents, S.K.; Fundamenski, W.; Matthews, G. F.; Pitts, R.A.

doi:10.1016/j.jnucmat.2004.09.032

Cited by 31 publications

(29 citation statements)

References 22 publications

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“…Consistent with our direct measurements of € Γ θ and simple neutral mean-free-path considerations, many edge simulations have found neutral penetration to be insufficient to 'close the loop' on the observed HFS plasma flow pattern [25,26 ] and impurity deposition patterns [27,28 ]. The authors of these studies have suggested that an inward particle pinch might play a role in the HFS scrape-off layer, pulling ions back into the confined plasma.…”

Section: Inward Particle Pinch On Hfs Midplane?supporting

confidence: 83%

“…This has prompted speculation that an inward convection mechanism may exist on the HFS midplane or divertor leg (e.g. [25,26]) -perhaps a turbulent transport mechanism, akin to the 'blobs' that are found on the LFS. In addition, transport analysis of CH4 introduced into the DIII-D SOL and its deposition pattern in the inner divertor region suggest that some kind of inward transport mechanism is active there [27,28].…”

Section: Introductionmentioning

confidence: 99%

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Transport and drift-driven plasma flow components in the Alcator C-Mod boundary plasma

Smick¹,

LaBombard²,

Hutchinson³

2013

Nucl. Fusion

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Boundary layer flows in the Alcator C-Mod tokamak are systematically examined as magnetic topology (upper versus lower-null) and plasma density are changed. Utilizing a unique set of scanning Langmuir-Mach probes, including one on the high-field side midplane, the poloidal variation of plasma flow components in the parallel, diamagnetic and radial directions are resolved in detail. It is found that the plasma flow pattern can be decomposed into two principal parts: (1) a drift-driven component, which lies within a magnetic flux surface and is divergence-free and (2) a transport-driven component, which gives rise to near-sonic parallel flows on the high-field side scrape-off layer. Toroidal rotation, Pfirsch-Schlüter and transport-driven contributions are unambiguously identified. Transport-driven parallel flows are found to dominate the high-field side particle fluxes; the total poloidal-directed flow accounts for ~1/3 to all of the ion flux arriving on the inner divertor. As a result, heat convection is found to be an important player in this region, consistent with the observation of divertor asymmetries that depend on the direction of B ×∇B relative to the active x-point. In contrast, the poloidal projection of parallel flow in the low-field scrape-off layer largely cancels with E r ×B flow; toroidal rotation is the dominant plasma motion there. The magnitude of the transport-driven poloidal flow is found to be quantitatively consistent with fluctuation-induced radial particle fluxes on the low-field side, identifying this as the primary drive mechanism. Fluctuation-induced fluxes on the high-field side are found to be essentially zero, excluding turbulent inward transport as the mechanism that closes the circulation loop in this region.

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Section: Inward Particle Pinch On Hfs Midplane?supporting

confidence: 83%

Section: Introductionmentioning

confidence: 99%

Transport and drift-driven plasma flow components in the Alcator C-Mod boundary plasma

Smick¹,

LaBombard²,

Hutchinson³

2013

Nucl. Fusion

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“…This flow is directed from the outer to inner divertor for the usual B direction (ion B×∇B drift towards the divertor), like in experiment, and roughly compensates the E×B drift in the SOL [525], resulting in a toroidal rotation of the SOL plasma. However, the experiments show factor 2 to 5 higher Mach numbers [111,313,526], and the effect of the drifts on divertor asymmetry, especially with reversed magnetic field, still remains to be demonstrated in the modelling [27,527].…”

Section: Development Of Predictive Codesmentioning

confidence: 99%

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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“…A common conclusion is that poloidally asymmetric parallel flows are both a cause and a symptom of these differences [9]. Along with these experimental studies, numerical models have been used to get insights on the underlying physical mechanisms that lead to such asymmetries [10][11][12][13]. The common conclusion is that the inclusion of anomalous, ballooning-like cross-field transport is required in order to reproduce the general qualitative behaviour observed in the experiments.…”

Section: Introductionmentioning

confidence: 99%

Effect of the limiter position on the scrape-off layer width, radial electric field and intrinsic flows

et al. 2014

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The effect of the limiter position on the scrape-off layer (SOL) width, radial electric field and intrinsic flows is investigated via global, three-dimensional turbulence simulations in four different limiter configurations. The limiter position affects the SOL dynamics in a number of ways, for example by changing the effective connection length or by modifying the unstable modes present in the system. The simulations show that the SOL width is much smaller and less poloidally asymmetric when the plasma is limited on the low-field side than on the high-field side, which can be explained by a change in the turbulence regime between the two configurations. The radial electric field is determined by the combined effect of the sheath physics and the electron adiabaticity condition, and its poloidal structure depends on the limiter position, as it can be fairly well explained through an analytical model. Intrinsic parallel flows established in the SOL, typically leading to co-current toroidal rotation with a magnitude that strongly depends on the limiter position, can also be fairly well reproduced analytically for each limiter configuration.

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EDGE2D code simulations of SOL flows and in–out divertor asymmetries in JET

Cited by 31 publications

References 22 publications

Transport and drift-driven plasma flow components in the Alcator C-Mod boundary plasma

Transport and drift-driven plasma flow components in the Alcator C-Mod boundary plasma

Chapter 4: Power and particle control

Effect of the limiter position on the scrape-off layer width, radial electric field and intrinsic flows

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