Plasma decontamination during preliminary ergodic divertor experiments in TORE SUPRA

Breton, C.; Michelis, C. De; Mattioli, M.; Monier‐Garbet, P.; Agostini, Eric; Fall, T.; Hess, W.; Lasalle, J.; Evans, T.E.; Grosman, A.; Ghendrih, Ph.; Pecquet, A.‐L.; Poutchy, L.; Samain, A.; Vallet, J.C.

doi:10.1088/0029-5515/31/9/017

Cited by 39 publications

(31 citation statements)

References 15 publications

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“…There have been many observations of impurity screening or core decontamination in tokamaks with MP application [22,23,111,[123][124][125][126] and in helical devices with a stochastic layer [127][128][129][130][131][132][133][134] or with the island divertor configurations [75,135]. Evidence of decontamination or screening effects is found for several impurity species, e.g.…”

Section: Observations Of Core Decontamination or Impurity Screening W...mentioning

confidence: 99%

3D effects of edge magnetic field configuration on divertor/scrape-off layer transport and optimization possibilities for a future reactor

Kobayashi

Ida

et al. 2015

Nucl. Fusion

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This paper assesses the 3D effects of edge magnetic field structure on divertor/SOL transport, based on inter-machine comparison of experimental data and on the recent progress of 3D edge transport simulation. The 3D effects are elucidated as a consequence of competition between transports parallel (//) and perpendicular () to magnetic field, in open field lines cut by divertor plates, or in magnetic islands. The competition has strong impacts on divertor functions, such as determination of the divertor density regime, impurity screening and detachment control. The effects of magnetic perturbation on the edge electric field and turbulent transport are also discussed. Parameterization to measure the 3D effects on the edge transport is attempted for the individual divertor functions. Based on the suggested key parameters, an operation domain of the 3D divertor configuration is discussed for future devices.

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Section: Observations Of Core Decontamination or Impurity Screening W...mentioning

confidence: 99%

3D effects of edge magnetic field configuration on divertor/scrape-off layer transport and optimization possibilities for a future reactor

Kobayashi

Ida

et al. 2015

Nucl. Fusion

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“…There have been many observations of impurity screening or core decontamination in tokamaks with RMP application [76,77,78], and in helical devices with a stochastic layer [79,80] or with the island divertor configurations [81,82]. It is not clear yet at all whether these phenomena are caused by the edge impurity screening or attributed to core transport or some other effects such as a change of source characteristic, etc.…”

Section: Impact On Sol and Divertor Impurity Transportmentioning

confidence: 99%

Impact of 3D magnetic field structure on boundary and divertor plasmas in stellarator/heliotron devices

Kobayashi

Feng

et al. 2015

Journal of Nuclear Materials

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This paper overviews recent progress on the experimental identification and physics interpretation of 3D effects of magnetic field geometry on divertor transport. The 3D effects are elucidated as a consequence of competition between transports parallel (//) and perpendicular () to magnetic field, in open field lines cut by divertor plates, or in magnetic islands. The competition has strong impacts on divertor functions, such as determination of density regime, impurity screening, and detachment control. The effects of magnetic perturbation on the edge electric field and turbulent transport are also discussed. Based on the experiments and numerical simulations, key parameters governing the 3D transport physics for the individual divertor functions, e.g. pumping efficiency through divertor density regime, impurity screening and detachment control, are discussed.

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“…On the other hand, extensive studies on the impurity behavior due to ergodization of the edge magnetic fields have been carried out on Tore Supra. In Tore Supra the activation of the ED led to a significant reduction in the concentration of intrinsic impurities and to an appreciable enhancement of the radiation from the plasma edge 8 . The ED worked differently on each ionization state of highly charged impurity ions 9 .…”

Section: Introductionmentioning

confidence: 99%

Experimental study of impurity screening in the edge ergodic layer of the Large Helical Device using carbon emissions of CIII to CVI

et al. 2009

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observed in VUV and EUV regions to study the edge carbon impurity transport in the LHD ergodic layer. Here, CIII and CIV indicate the carbon influx at the outside boundary of the ergodic layer and CV and CVI indicate the ions in higher ionization stages which have already experienced the transport in the ergodic layer. The intensity ratio of CV+CVI to CIII+CIV, therefore, represents the degree of impurity screening, which has been analyzed with different edge plasma parameters and ergodic magnetic field structures. The ratio decreases by two orders of magnitude with an increase of electron density, n e , in the range of 1810 19 m -3 . The CV and CVI emissions tend to decrease with n e , whereas the CIII and CIV emissions monotonically increase with n e .-2 -The result suggests an enhancement of the impurity screening in the higher n e range due to the increasing ion-impurity collision frequency ( Zi 1/ s =3.4×10 plays an important role in the edge impurity transport within the ergodic layer. When the ergodic layer structure is thicker, the ratio systematically decreases mainly due to a reduction of CV+CVI emissions. The ratio is also studied by changing the radial position of an externally supplied m/n=1/1 islands. When the island is positioned in the ergodic layer, the ratio indicates a remarkable change, i.e. reduction of CV+CVI and increase ofCIII+CIV. These experiments demonstrate that the modification of the ergodic magnetic field structure makes a clear change to the edge impurity transport. When the background ion species is changed from hydrogen to helium, the ratio is clearly reduced, at least at n e 4×10 19 m -3 , suggesting the enhancement of the impurity screening effect due to the increased collisionality. Finally, the experimental result is simulated using 3-dimenstional edge transport code of EMC3-EIRENE. The density dependence of the carbon ratio can be well reproduced with a simulation code suggesting that impurity screening is induced in the ergodic magnetic field layer.

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Plasma decontamination during preliminary ergodic divertor experiments in TORE SUPRA

Cited by 39 publications

References 15 publications

3D effects of edge magnetic field configuration on divertor/scrape-off layer transport and optimization possibilities for a future reactor

3D effects of edge magnetic field configuration on divertor/scrape-off layer transport and optimization possibilities for a future reactor

Impact of 3D magnetic field structure on boundary and divertor plasmas in stellarator/heliotron devices

Experimental study of impurity screening in the edge ergodic layer of the Large Helical Device using carbon emissions of CIII to CVI

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