Driving mechanism of sol plasma flow and effects on the divertor performance in JT-60U

Asakura, N.; Takenaga, H.; Sakurai, S.; Porter, G. D.; Rognlien, T. D.; Rensink, M.E.; Shimizu, K.; Higashijima, S.; Kubo, H.

doi:10.1088/0029-5515/44/4/004

Cited by 78 publications

(94 citation statements)

References 23 publications

(29 reference statements)

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“…SOLPS modelling however predicts smaller values, roughly by factor 3, as shown below. On JT-60U, measured ion flows were also found to be by factor ~ 2 above those predicted by the UEDGE code [6].…”

Section: Introductionmentioning

confidence: 83%

A possible role of radial electric field in driving parallel ion flow in scrape-off layer of divertor tokamaks

Chankin¹,

Coster²,

Asakura³

et al. 2007

Nucl. Fusion

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The radial electric field in known to be one of the drivers of parallel ion flow in the SOL. It contributes to the ion Pfirsch-Schlüter flow and also determines the 'return parallel flow' that can arise to compensate poloidal E×B drift. It was established recently that 2D fluid codes EDGE2D and SOLPS underestimate the predicted E r in the SOL compared to experimentally measured values. The underestimate is likely to be related with kinetic effects of parallel transport by heat-carrying electrons. The present work demonstrates that this underestimate can be responsible for the large discrepancy between measured and simulated parallel ion flows in the SOL observed in a number of experiments. Were the radial electric field modelled correctly by the codes, a significant increase in the predicted Mach number of the parallel ion flow could be expected. For the part of the ion flow that depends on the toroidal field direction, this would greatly reduce, or even possibly eliminate, the difference between the experiment and model, as concluded from the comparison between measured and simulated radial electric fields and Mach numbers of the parallel ion flow in JET and ASDEX Upgrade.2

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Section: Introductionmentioning

confidence: 83%

A possible role of radial electric field in driving parallel ion flow in scrape-off layer of divertor tokamaks

Chankin¹,

Coster²,

Asakura³

et al. 2007

Nucl. Fusion

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“…Argon accumulation was found to be modest and well within acceptable levels [140]. JT-60U [141], JET [115] and C-Mod (inner wall probe only) [114], (after [142]). …”

Section: Use Of Extrinsic Impurity Radiation To Reduce Divertor Heat mentioning

confidence: 89%

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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“…[7][8][9] The scrape-off layer (SOL) flow at various poloidal locations has been measured in many divertor tokamaks with both normal and reversed fields. [10][11][12][13][14] Most of the experimental results are obtained by Mach probes. A number of possible mechanisms to drive the parallel SOL flow have been suggested, including ion Pfirsch-Schlüter (PS) flow, ballooning transport, flow reversal driven by localized ionization, momentum transfer, and co-current toroidal momentum generated in the SOL by ion !B and centrifugal drifts.…”

Section: Introductionmentioning

confidence: 99%

“…10 There are some experimental evidences that the PS flow appears to make an important contribution to the observed parallel flow, because the direction of the parallel flow is reversed when the magnetic field is reversed. [10][11][12][13]15 In addition, It has been demonstrated by the measurements of the SOL flow in different divertor configurations at both high field side (HFS) and low field side (LFS) in Alcator C-Mod tokamak 12,13 that a ballooning-like transport is the most important contributing mechanism to the asymmetry in the HFS-LFS SOL flow, albeit some other mechanisms, including toroidal plasma rotation and PS ion currents, also contribute. 5,12 Detailed analysis of poloidal particle flux has also been made to reveal dominating mechanisms for the SOL particle transport.…”

Section: Introductionmentioning

confidence: 99%

“…5,12 Detailed analysis of poloidal particle flux has also been made to reveal dominating mechanisms for the SOL particle transport. 11 Experimental of the divertor asymmetry between the configurations with the ion !B drift away and toward the active X-point, thus demonstrating the effect of classical drifts. Furthermore, the plasma flow has been measured with the fast moving reciprocating probe at the outer midplane.…”

Section: Introductionmentioning

confidence: 99%

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Divertor asymmetry and scrape-off layer flow in various divertor configurations in Experimental Advanced Superconducting Tokamak

Liu

Guo

et al. 2012

Physics of Plasmas

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Divertor asymmetry and its dependence on the ion !B direction has been investigated in the Experimental Advanced Superconducting Tokamak by changing the divertor configuration from lower single null (LSN), via double null (DN), to upper single null (USN) during one single discharge. Divertor plasmas exhibit the usual in-out asymmetry in particle and heat fluxes in LSN with the ion !B direction toward the lower X-point, favoring the outer divertor, especially at high density. The in-out asymmetry is reversed when changing the divertor configuration from LSN to USN, thus clearly demonstrating the effect of classical drifts. DN exhibits an even stronger in-out divertor asymmetry, favoring the outer divertor. A significant top-down asymmetry is also seen for DN, with greater particle and heat fluxes to the bottom divertor. In addition, the parallel plasma flow has been measured by a fast moving Mach probe at the outer midplane, which shows similar magnitude to the Pfirsch-Schlüter flow. Its contribution to the poloidal particle flux is also assessed and comparison is made with that from the poloidal E Â B drift. V C 2012 American Institute of Physics. [http://dx

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Driving mechanism of sol plasma flow and effects on the divertor performance in JT-60U

Cited by 78 publications

References 23 publications

A possible role of radial electric field in driving parallel ion flow in scrape-off layer of divertor tokamaks

A possible role of radial electric field in driving parallel ion flow in scrape-off layer of divertor tokamaks

Chapter 4: Power and particle control

Divertor asymmetry and scrape-off layer flow in various divertor configurations in Experimental Advanced Superconducting Tokamak

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