The ASDEX upgrade divertor IIb - A closed divertor for strongly shaped plasmas

R. Neu; J. C. Fuchs; A. Kallenbach; C. Maggi; V. Rohde; F. Ryter; T. Eich; J. Gafert; O. Gruber; G. Haas; A. Herrmann; M. Kaufmann; M. Laux; V. Mertens; H. W. Müller; J. Neuhauser; T. Pütterich; J. Stober; S. W. Yoon

doi:10.1088/0029-5515/43/10/021

The ASDEX upgrade divertor IIb - A closed divertor for strongly shaped plasmas

R. Neu, J. C. Fuchs, A. Kallenbach, C. Maggi, V. Rohde, F. Ryter, T. Eich, J. Gafert, O. Gruber, G. Haas, A. Herrmann, M. Kaufmann, M. Laux, V. Mertens, H. W. Müller, J. Neuhauser, T. Pütterich, J. Stober, S. W. Yoon

Max Planck Institute for Plasma Physics

Research output: Contribution to journal › Article › peer-review

22 Scopus citations

Abstract

A new divertor configuration (DIV-IIb) has been implemented in ASDEX Upgrade. In order to accommodate a large variety of plasma shapes with bottom triangularities (δ_bot) up to 0.48, the outer strikepoint region was modified and the roof baffle was lowered and diminished at its outer part in comparison with the previous divertor (DIV-II). The inner part of the divertor strikepoint module remains unchanged, but a smooth transition to the central column is provided at the divertor entrance to minimize local hydrogen recycling. An increase in power density is observed due to geometrical reasons at the outer target, whereas the divertor radiation for similar configurations and discharge conditions is unchanged. The pumping characteristics for D and He are almost retained, suggesting a large influence of the inner divertor leg, the configuration of which remains as before. Detachment in L-mode discharges fits well into a scaling deduced from JET data and earlier ASDEX Upgrade data. A significant reduction (20%) of the L-H threshold is observed compared with DIV-II. Its density dependence is weaker than in the previous DIV-II configuration and there are hints for an influence of triangularity on power threshold. Finally, clear evidence for a parasitic plasma below the divertor roof baffle is found.

Original language	English
Pages (from-to)	1191-1196
Number of pages	6
Journal	Nuclear Fusion
Volume	43
Issue number	10
DOIs	https://doi.org/10.1088/0029-5515/43/10/021
State	Published - Oct 2003
Externally published	Yes

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Neu, R., Fuchs, J. C., Kallenbach, A., Maggi, C., Rohde, V., Ryter, F., Eich, T., Gafert, J., Gruber, O., Haas, G., Herrmann, A., Kaufmann, M., Laux, M., Mertens, V., Müller, H. W., Neuhauser, J., Pütterich, T., Stober, J., & Yoon, S. W. (2003). The ASDEX upgrade divertor IIb - A closed divertor for strongly shaped plasmas. Nuclear Fusion, 43(10), 1191-1196. https://doi.org/10.1088/0029-5515/43/10/021

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title = "The ASDEX upgrade divertor IIb - A closed divertor for strongly shaped plasmas",

abstract = "A new divertor configuration (DIV-IIb) has been implemented in ASDEX Upgrade. In order to accommodate a large variety of plasma shapes with bottom triangularities (δbot) up to 0.48, the outer strikepoint region was modified and the roof baffle was lowered and diminished at its outer part in comparison with the previous divertor (DIV-II). The inner part of the divertor strikepoint module remains unchanged, but a smooth transition to the central column is provided at the divertor entrance to minimize local hydrogen recycling. An increase in power density is observed due to geometrical reasons at the outer target, whereas the divertor radiation for similar configurations and discharge conditions is unchanged. The pumping characteristics for D and He are almost retained, suggesting a large influence of the inner divertor leg, the configuration of which remains as before. Detachment in L-mode discharges fits well into a scaling deduced from JET data and earlier ASDEX Upgrade data. A significant reduction (20%) of the L-H threshold is observed compared with DIV-II. Its density dependence is weaker than in the previous DIV-II configuration and there are hints for an influence of triangularity on power threshold. Finally, clear evidence for a parasitic plasma below the divertor roof baffle is found.",

author = "R. Neu and Fuchs, {J. C.} and A. Kallenbach and C. Maggi and V. Rohde and F. Ryter and T. Eich and J. Gafert and O. Gruber and G. Haas and A. Herrmann and M. Kaufmann and M. Laux and V. Mertens and M{\"u}ller, {H. W.} and J. Neuhauser and T. P{\"u}tterich and J. Stober and Yoon, {S. W.}",

year = "2003",

month = oct,

doi = "10.1088/0029-5515/43/10/021",

language = "English",

volume = "43",

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journal = "Nuclear Fusion",

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Neu, R, Fuchs, JC, Kallenbach, A, Maggi, C, Rohde, V, Ryter, F, Eich, T, Gafert, J, Gruber, O, Haas, G, Herrmann, A, Kaufmann, M, Laux, M, Mertens, V, Müller, HW, Neuhauser, J, Pütterich, T, Stober, J & Yoon, SW 2003, 'The ASDEX upgrade divertor IIb - A closed divertor for strongly shaped plasmas', Nuclear Fusion, vol. 43, no. 10, pp. 1191-1196. https://doi.org/10.1088/0029-5515/43/10/021

TY - JOUR

T1 - The ASDEX upgrade divertor IIb - A closed divertor for strongly shaped plasmas

AU - Neu, R.

AU - Fuchs, J. C.

AU - Kallenbach, A.

AU - Maggi, C.

AU - Rohde, V.

AU - Ryter, F.

AU - Eich, T.

AU - Gafert, J.

AU - Gruber, O.

AU - Haas, G.

AU - Herrmann, A.

AU - Kaufmann, M.

AU - Laux, M.

AU - Mertens, V.

AU - Müller, H. W.

AU - Neuhauser, J.

AU - Pütterich, T.

AU - Stober, J.

AU - Yoon, S. W.

PY - 2003/10

Y1 - 2003/10

N2 - A new divertor configuration (DIV-IIb) has been implemented in ASDEX Upgrade. In order to accommodate a large variety of plasma shapes with bottom triangularities (δbot) up to 0.48, the outer strikepoint region was modified and the roof baffle was lowered and diminished at its outer part in comparison with the previous divertor (DIV-II). The inner part of the divertor strikepoint module remains unchanged, but a smooth transition to the central column is provided at the divertor entrance to minimize local hydrogen recycling. An increase in power density is observed due to geometrical reasons at the outer target, whereas the divertor radiation for similar configurations and discharge conditions is unchanged. The pumping characteristics for D and He are almost retained, suggesting a large influence of the inner divertor leg, the configuration of which remains as before. Detachment in L-mode discharges fits well into a scaling deduced from JET data and earlier ASDEX Upgrade data. A significant reduction (20%) of the L-H threshold is observed compared with DIV-II. Its density dependence is weaker than in the previous DIV-II configuration and there are hints for an influence of triangularity on power threshold. Finally, clear evidence for a parasitic plasma below the divertor roof baffle is found.

AB - A new divertor configuration (DIV-IIb) has been implemented in ASDEX Upgrade. In order to accommodate a large variety of plasma shapes with bottom triangularities (δbot) up to 0.48, the outer strikepoint region was modified and the roof baffle was lowered and diminished at its outer part in comparison with the previous divertor (DIV-II). The inner part of the divertor strikepoint module remains unchanged, but a smooth transition to the central column is provided at the divertor entrance to minimize local hydrogen recycling. An increase in power density is observed due to geometrical reasons at the outer target, whereas the divertor radiation for similar configurations and discharge conditions is unchanged. The pumping characteristics for D and He are almost retained, suggesting a large influence of the inner divertor leg, the configuration of which remains as before. Detachment in L-mode discharges fits well into a scaling deduced from JET data and earlier ASDEX Upgrade data. A significant reduction (20%) of the L-H threshold is observed compared with DIV-II. Its density dependence is weaker than in the previous DIV-II configuration and there are hints for an influence of triangularity on power threshold. Finally, clear evidence for a parasitic plasma below the divertor roof baffle is found.

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U2 - 10.1088/0029-5515/43/10/021

DO - 10.1088/0029-5515/43/10/021

M3 - Article

AN - SCOPUS:0242380280

SN - 0029-5515

VL - 43

SP - 1191

EP - 1196

JO - Nuclear Fusion

JF - Nuclear Fusion

IS - 10

ER -

The ASDEX upgrade divertor IIb - A closed divertor for strongly shaped plasmas

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