Edge Plasma Transport in the Helical Divertor Configuration in LHD

Masuzaki, S.; Kobayashi, M.; Murase, Takuhei; Morisaki, T.; Tokitani, M.; Ohyabu, N.; Yamada, H.; Komori, A.

doi:10.1002/ctpp.200900047

Cited by 10 publications

(14 citation statements)

References 11 publications

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“…However, there is an insufficiently understood footprint modification depending on the edge electron temperature (T e,edge ). In the experiment, private-side peak appears on the divertor flux profile when T e,edge is high, and it disappears when T e,edge is low [6]. In the numerical modeling, however, such experimentally observed private-side peak has not been reproduced by using the 3D transport code EMC3-EIRENE even with introducing spatially non-uniform cross-field transport coefficients [7].…”

Section: Introductionmentioning

confidence: 90%

Characterized divertor footprint profile modification with the edge pressure gradient in the Large Helical Device

Tanaka¹,

Masuzaki²,

Kawamura³

et al. 2018

Plasma Phys. Control. Fusion

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The first attempt to characterize the divertor footprint profile in the heliotron device LHD was done, by using a number of Langmuir probes and the multivariable analysis technique.In order to clarify the generation mechanism of the private-side peak on the footprint profile, which has not been reproduced in the modeling study, over 6000 time points were extracted by excluding time points with profile modifications due to already-known reasons. A characterization index ⁄ was newly defined from the multivariable analysis result, and its dependences on upstream parameters were investigated. As a result, it was found that the footprint profile correlates with the pressure gradient at the edge inside the core region with a fixed beta, suggesting that change of the plasma pressure profile could modify the edge magnetic field structure even if the volume integral of the plasma pressure was constant.

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Section: Introductionmentioning

confidence: 90%

Characterized divertor footprint profile modification with the edge pressure gradient in the Large Helical Device

Tanaka¹,

Masuzaki²,

Kawamura³

et al. 2018

Plasma Phys. Control. Fusion

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“…In the case of LHD, the strike line structure on the helical divertor [4] is influenced by the complex magnetic edge topology. Previous attempts [5] to verify numerical models of the divertor heat flux at LHD with Langmuir probe measurements showed good qualitative agreement. Changes in different density regimes could be correlated to changing cross field transport.…”

Section: Introductionmentioning

confidence: 76%

Comparison of Observed Divertor Heat Flux and Modeling Results at LHD

Drewelow

Masuzaki

Bozhenkov

et al. 2013

Plasma and Fusion Research

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The divertor strike line pattern on the helical divertor of LHD was observed with an infra red camera. The derived heat flux pattern show multiple distinct strike lines depending on the equilibrium magnetic configuration. Predictions of such divertor heat loads thus require a modeling of the magnetic configuration and the heat transport in the magnetic edge. Equilibrium magnetic topologies were analyzed with HINT2, while the plasma fluid model code EMC3 was used to simulate the energy transport in the edge. The measured multi peak structure of the divertor heat flux is correlated to the intersection points of elongated loop shaped flux tubes of long L C field lines. But the fluid model could not recreate the total energy load and the multiple heat flux peaks on the divertor. A Variation in the plasma density n e as a transport parameter in order to fit the simulated heat flux to the measured one shows a contradicting tendency.

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“…Instead, the last cell of the divertor legs in the plasma domain is traced along field lines to the divertor surface, providing the particle deposition pattern on the divertor plates [19][20][21].…”

Section: Simulation Setupmentioning

confidence: 99%

Modeling of helium transport and exhaust in the LHD edge

Bader

Kobayashi

Schmitz

et al. 2016

Plasma Phys. Control. Fusion

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Experimental results from LHD show a reduction of helium concentration in the plasma with the introduction of a magnetic island on the m/n = 1/1 resonant surface in the plasma edge. Simulations of the plasma with and without the island are carried out with the coupled code EMC3-EIRENE and compared to Charge Exchange Recombination Spectroscopy measurements of ionized core helium, and Visible Spectroscopy measurements of edge neutral helium. The numerical simulations indicate that the experimental parameters lie in a high density regime where the impurity transport is dominated by the outward directed friction force. The EMC3-EIRENE simulations capture the reduction in helium transport well and indicate that: 1) the reduction in core helium is a result of increased outward transport caused by the magnetic island and an increased opening of the edge-surface layer to the divertor plates; 2) the dominant source of neutral helium is best modeled by recycled helium at the targets; and 3) ionized helium density profiles are best matched in the simulations when there is a large core helium source in addition to a smaller edge source.

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Edge Plasma Transport in the Helical Divertor Configuration in LHD

Cited by 10 publications

References 11 publications

Characterized divertor footprint profile modification with the edge pressure gradient in the Large Helical Device

Characterized divertor footprint profile modification with the edge pressure gradient in the Large Helical Device

Comparison of Observed Divertor Heat Flux and Modeling Results at LHD

Modeling of helium transport and exhaust in the LHD edge

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