Results from recent detachment experiments in alternative divertor configurations on TCV

C. Theiler; B. Lipschultz; J. Harrison; B. Labit; H. Reimerdes; C. Tsui; W. A.J. Vijvers; J. A. Boedo; B. P. Duval; S. Elmore; P. Innocente; U. Kruezi; T. Lunt; R. Maurizio; F. Nespoli; U. Sheikh; A. J. Thornton; S. H.M. Van Limpt; K. Verhaegh; N. Vianello

doi:10.1088/1741-4326/aa5fb7

Results from recent detachment experiments in alternative divertor configurations on TCV

C. Theiler, B. Lipschultz, J. Harrison, B. Labit, H. Reimerdes, C. Tsui, W. A.J. Vijvers, J. A. Boedo, B. P. Duval, S. Elmore, P. Innocente, U. Kruezi, T. Lunt, R. Maurizio, F. Nespoli, U. Sheikh, A. J. Thornton, S. H.M. Van Limpt, K. Verhaegh, N. Vianello

Physics

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

Abstract

Divertor detachment is explored on the TCV tokamak in alternative magnetic geometries. Starting from typical TCV single-null shapes, the poloidal flux expansion at the outer strikepoint is varied by a factor of 10 to investigate the X-divertor characteristics, and the total flux expansion is varied by 70% to study the properties of the super-X divertor. The effect of an additional X-point near the target is investigated in X-point target divertors. Detachment of the outer target is studied in these plasmas during Ohmic density ramps and with the ion ∇B drift away from the primary X-point. The detachment threshold, depth of detachment, and the stability of the radiation location are investigated using target measurements from the wall-embedded Langmuir probes and two-dimensional CIII line emissivity profiles across the divertor region, obtained from inverted, toroidally-integrated camera data. It is found that increasing poloidal flux expansion results in a deeper detachment for a given line-averaged density and a reduction in the radiation location sensitivity to core density, while no large effect on the detachment threshold is observed. The total flux expansion, contrary to expectations, does not show a significant influence on any detachment characteristics in these experiments. In X-point target geometries, no evidence is found for a reduced detachment threshold despite a 2-3 fold increase in connection length. A reduced radiation location sensitivity to core plasma density in the vicinity of the target X-point is suggested by the measurements.

Original language	English
Article number	072008
Number of pages	16
Journal	Nuclear Fusion
Volume	57
Issue number	7
DOIs	https://doi.org/10.1088/1741-4326/aa5fb7
Publication status	Published - 21 Mar 2017

Bibliographical note

Keywords

Alternative divertors
Detachment
Super-X divertor
X-divertor
X-point target divertor

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10.1088/1741-4326/aa5fb7Licence: CC BY

Theiler_2017_Nucl._Fusion_57_072008
© 2017, Ecole Polytechnique Federale de Lausanne.
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Cite this

Theiler, C., Lipschultz, B., Harrison, J., Labit, B., Reimerdes, H., Tsui, C., Vijvers, W. A. J., Boedo, J. A., Duval, B. P., Elmore, S., Innocente, P., Kruezi, U., Lunt, T., Maurizio, R., Nespoli, F., Sheikh, U., Thornton, A. J., Van Limpt, S. H. M., Verhaegh, K., & Vianello, N. (2017). Results from recent detachment experiments in alternative divertor configurations on TCV. Nuclear Fusion, 57(7), Article 072008. https://doi.org/10.1088/1741-4326/aa5fb7

@article{31d00d74cee54098857218d13f04cdad,

title = "Results from recent detachment experiments in alternative divertor configurations on TCV",

abstract = "Divertor detachment is explored on the TCV tokamak in alternative magnetic geometries. Starting from typical TCV single-null shapes, the poloidal flux expansion at the outer strikepoint is varied by a factor of 10 to investigate the X-divertor characteristics, and the total flux expansion is varied by 70% to study the properties of the super-X divertor. The effect of an additional X-point near the target is investigated in X-point target divertors. Detachment of the outer target is studied in these plasmas during Ohmic density ramps and with the ion ∇B drift away from the primary X-point. The detachment threshold, depth of detachment, and the stability of the radiation location are investigated using target measurements from the wall-embedded Langmuir probes and two-dimensional CIII line emissivity profiles across the divertor region, obtained from inverted, toroidally-integrated camera data. It is found that increasing poloidal flux expansion results in a deeper detachment for a given line-averaged density and a reduction in the radiation location sensitivity to core density, while no large effect on the detachment threshold is observed. The total flux expansion, contrary to expectations, does not show a significant influence on any detachment characteristics in these experiments. In X-point target geometries, no evidence is found for a reduced detachment threshold despite a 2-3 fold increase in connection length. A reduced radiation location sensitivity to core plasma density in the vicinity of the target X-point is suggested by the measurements.",

keywords = "Alternative divertors, Detachment, Super-X divertor, X-divertor, X-point target divertor",

author = "C. Theiler and B. Lipschultz and J. Harrison and B. Labit and H. Reimerdes and C. Tsui and Vijvers, {W. A.J.} and Boedo, {J. A.} and Duval, {B. P.} and S. Elmore and P. Innocente and U. Kruezi and T. Lunt and R. Maurizio and F. Nespoli and U. Sheikh and Thornton, {A. J.} and {Van Limpt}, {S. H.M.} and K. Verhaegh and N. Vianello",

note = "{\textcopyright} 2017, Ecole Polytechnique Federale de Lausanne.",

year = "2017",

month = mar,

day = "21",

doi = "10.1088/1741-4326/aa5fb7",

language = "English",

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Theiler, C, Lipschultz, B, Harrison, J, Labit, B, Reimerdes, H, Tsui, C, Vijvers, WAJ, Boedo, JA, Duval, BP, Elmore, S, Innocente, P, Kruezi, U, Lunt, T, Maurizio, R, Nespoli, F, Sheikh, U, Thornton, AJ, Van Limpt, SHM, Verhaegh, K & Vianello, N 2017, 'Results from recent detachment experiments in alternative divertor configurations on TCV', Nuclear Fusion, vol. 57, no. 7, 072008. https://doi.org/10.1088/1741-4326/aa5fb7

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AU - Theiler, C.

AU - Lipschultz, B.

AU - Harrison, J.

AU - Labit, B.

AU - Reimerdes, H.

AU - Tsui, C.

AU - Vijvers, W. A.J.

AU - Boedo, J. A.

AU - Duval, B. P.

AU - Elmore, S.

AU - Innocente, P.

AU - Kruezi, U.

AU - Lunt, T.

AU - Maurizio, R.

AU - Nespoli, F.

AU - Sheikh, U.

AU - Thornton, A. J.

AU - Van Limpt, S. H.M.

AU - Verhaegh, K.

AU - Vianello, N.

PY - 2017/3/21

Y1 - 2017/3/21

N2 - Divertor detachment is explored on the TCV tokamak in alternative magnetic geometries. Starting from typical TCV single-null shapes, the poloidal flux expansion at the outer strikepoint is varied by a factor of 10 to investigate the X-divertor characteristics, and the total flux expansion is varied by 70% to study the properties of the super-X divertor. The effect of an additional X-point near the target is investigated in X-point target divertors. Detachment of the outer target is studied in these plasmas during Ohmic density ramps and with the ion ∇B drift away from the primary X-point. The detachment threshold, depth of detachment, and the stability of the radiation location are investigated using target measurements from the wall-embedded Langmuir probes and two-dimensional CIII line emissivity profiles across the divertor region, obtained from inverted, toroidally-integrated camera data. It is found that increasing poloidal flux expansion results in a deeper detachment for a given line-averaged density and a reduction in the radiation location sensitivity to core density, while no large effect on the detachment threshold is observed. The total flux expansion, contrary to expectations, does not show a significant influence on any detachment characteristics in these experiments. In X-point target geometries, no evidence is found for a reduced detachment threshold despite a 2-3 fold increase in connection length. A reduced radiation location sensitivity to core plasma density in the vicinity of the target X-point is suggested by the measurements.

AB - Divertor detachment is explored on the TCV tokamak in alternative magnetic geometries. Starting from typical TCV single-null shapes, the poloidal flux expansion at the outer strikepoint is varied by a factor of 10 to investigate the X-divertor characteristics, and the total flux expansion is varied by 70% to study the properties of the super-X divertor. The effect of an additional X-point near the target is investigated in X-point target divertors. Detachment of the outer target is studied in these plasmas during Ohmic density ramps and with the ion ∇B drift away from the primary X-point. The detachment threshold, depth of detachment, and the stability of the radiation location are investigated using target measurements from the wall-embedded Langmuir probes and two-dimensional CIII line emissivity profiles across the divertor region, obtained from inverted, toroidally-integrated camera data. It is found that increasing poloidal flux expansion results in a deeper detachment for a given line-averaged density and a reduction in the radiation location sensitivity to core density, while no large effect on the detachment threshold is observed. The total flux expansion, contrary to expectations, does not show a significant influence on any detachment characteristics in these experiments. In X-point target geometries, no evidence is found for a reduced detachment threshold despite a 2-3 fold increase in connection length. A reduced radiation location sensitivity to core plasma density in the vicinity of the target X-point is suggested by the measurements.

KW - Alternative divertors

KW - Detachment

KW - Super-X divertor

KW - X-divertor

KW - X-point target divertor

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DO - 10.1088/1741-4326/aa5fb7

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AN - SCOPUS:85020861714

SN - 0029-5515

VL - 57

JO - Nuclear Fusion

JF - Nuclear Fusion

IS - 7

M1 - 072008

ER -

Results from recent detachment experiments in alternative divertor configurations on TCV

Abstract

Bibliographical note

Keywords

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Bruce Lipschultz

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Results from recent detachment experiments in alternative divertor configurations on TCV

Abstract

Bibliographical note

Keywords

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Bruce Lipschultz

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