Overview and interpretation of L-H threshold experiments on JET with the ITER-like Wall

E. Delabie, C. Maggi, H. Meyer, T.M. Biewer, C. Bourdelle, M. Brix, I.S. Carvalho, M. Cleber, P. Drewelow, N. Hawkes, J. Hillesheim, A. Meigs, L. Meneses, F. Rimini, Paula Siren, E. Solano, M. Stamp

Research output: Chapter in Book/Report/Conference proceedingConference article in proceedingsScientific

Abstract

The expected threshold power (PL􀀀H) required to access H-mode operation on ITER is extrapolated from a multi-machine scaling that is strongly weighted to a dataset of JET carbon wall discharges [1]. Experiments on JET with the Be/W wall show a minimum in PL􀀀H as function of density and a favorable reduction in the threshold power of 30% at medium to high densities [2]. The carbon wall threshold can be recovered with nitrogen injection. An increase in the threshold power by up to a factor 2 and a reduction of the density at which the minimum occurs was found when the outer strike point position was moved from the horizontal to the vertical target. The existence of a critical min(Er;dia) is consistent with the threshold data from each of the divertor congurations but does not explain the dierences between them. The observation of a strong asymmetry between the inner and outer divertor that develops during a power ramp is correlated with the L-H threshold in the high density branch and indicates a direct eect of the scrape o layer or divertor conditions on the threshold. This mechanism also provides a qualitative explanation for dithering L-H transitions.
Original languageEnglish
Title of host publication25th IAEA Fusion Energy Conference
Subtitle of host publicationProgramme, Abstracts, and Contributions
PublisherInternational Atomic Energy Agency IAEA
PagesEX/P5-24
Number of pages8
Publication statusPublished - 2014
MoE publication typeB3 Non-refereed article in conference proceedings
Event25th Fusion Energy Conference, IAEA FEC 2014 - St.Petersburg, Russian Federation
Duration: 13 Oct 201418 Oct 2014
http://www-naweb.iaea.org/napc/physics/FEC/FEC2014/fec_sourcebook_online.pdf (Full proceedings)

Conference

Conference25th Fusion Energy Conference, IAEA FEC 2014
Abbreviated titleIAEA FEC 2014
CountryRussian Federation
CitySt.Petersburg
Period13/10/1418/10/14
Internet address

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thresholds
carbon
ramps
asymmetry
injection
scaling
nitrogen

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Delabie, E., Maggi, C., Meyer, H., Biewer, T. M., Bourdelle, C., Brix, M., ... Stamp, M. (2014). Overview and interpretation of L-H threshold experiments on JET with the ITER-like Wall. In 25th IAEA Fusion Energy Conference: Programme, Abstracts, and Contributions (pp. EX/P5-24). International Atomic Energy Agency IAEA.
Delabie, E. ; Maggi, C. ; Meyer, H. ; Biewer, T.M. ; Bourdelle, C. ; Brix, M. ; Carvalho, I.S. ; Cleber, M. ; Drewelow, P. ; Hawkes, N. ; Hillesheim, J. ; Meigs, A. ; Meneses, L. ; Rimini, F. ; Siren, Paula ; Solano, E. ; Stamp, M. / Overview and interpretation of L-H threshold experiments on JET with the ITER-like Wall. 25th IAEA Fusion Energy Conference: Programme, Abstracts, and Contributions. International Atomic Energy Agency IAEA, 2014. pp. EX/P5-24
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abstract = "The expected threshold power (PL􀀀H) required to access H-mode operation on ITER is extrapolated from a multi-machine scaling that is strongly weighted to a dataset of JET carbon wall discharges [1]. Experiments on JET with the Be/W wall show a minimum in PL􀀀H as function of density and a favorable reduction in the threshold power of 30{\%} at medium to high densities [2]. The carbon wall threshold can be recovered with nitrogen injection. An increase in the threshold power by up to a factor 2 and a reduction of the density at which the minimum occurs was found when the outer strike point position was moved from the horizontal to the vertical target. The existence of a critical min(Er;dia) is consistent with the threshold data from each of the divertor congurations but does not explain the dierences between them. The observation of a strong asymmetry between the inner and outer divertor that develops during a power ramp is correlated with the L-H threshold in the high density branch and indicates a direct eect of the scrape o layer or divertor conditions on the threshold. This mechanism also provides a qualitative explanation for dithering L-H transitions.",
author = "E. Delabie and C. Maggi and H. Meyer and T.M. Biewer and C. Bourdelle and M. Brix and I.S. Carvalho and M. Cleber and P. Drewelow and N. Hawkes and J. Hillesheim and A. Meigs and L. Meneses and F. Rimini and Paula Siren and E. Solano and M. Stamp",
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Delabie, E, Maggi, C, Meyer, H, Biewer, TM, Bourdelle, C, Brix, M, Carvalho, IS, Cleber, M, Drewelow, P, Hawkes, N, Hillesheim, J, Meigs, A, Meneses, L, Rimini, F, Siren, P, Solano, E & Stamp, M 2014, Overview and interpretation of L-H threshold experiments on JET with the ITER-like Wall. in 25th IAEA Fusion Energy Conference: Programme, Abstracts, and Contributions. International Atomic Energy Agency IAEA, pp. EX/P5-24, 25th Fusion Energy Conference, IAEA FEC 2014, St.Petersburg, Russian Federation, 13/10/14.

Overview and interpretation of L-H threshold experiments on JET with the ITER-like Wall. / Delabie, E.; Maggi, C.; Meyer, H.; Biewer, T.M.; Bourdelle, C.; Brix, M.; Carvalho, I.S.; Cleber, M.; Drewelow, P.; Hawkes, N.; Hillesheim, J.; Meigs, A.; Meneses, L.; Rimini, F.; Siren, Paula; Solano, E.; Stamp, M.

25th IAEA Fusion Energy Conference: Programme, Abstracts, and Contributions. International Atomic Energy Agency IAEA, 2014. p. EX/P5-24.

Research output: Chapter in Book/Report/Conference proceedingConference article in proceedingsScientific

TY - GEN

T1 - Overview and interpretation of L-H threshold experiments on JET with the ITER-like Wall

AU - Delabie, E.

AU - Maggi, C.

AU - Meyer, H.

AU - Biewer, T.M.

AU - Bourdelle, C.

AU - Brix, M.

AU - Carvalho, I.S.

AU - Cleber, M.

AU - Drewelow, P.

AU - Hawkes, N.

AU - Hillesheim, J.

AU - Meigs, A.

AU - Meneses, L.

AU - Rimini, F.

AU - Siren, Paula

AU - Solano, E.

AU - Stamp, M.

N1 - HUO: Poster presentation CO:U FOM Institute DIFFER, Association EURATOM-FOM, Nieuwegein, The Netherlands CO:Max-Planck-Institut für Plasmaphysik, Germany CO:Culham Science Centre, United Kingdom CO:Oak Ridge National Laboratory, TN, USA CO:U CEA-IRFM, Saint Paul lez Durance, France CO:Culham Science Centre, United Kingdom CO:U Institute of Plasmas and Nuclear Fusion, Association EURATOM/IST, Lisbon, Portugal CO:Forschungszentrum Jülich GmbH, Germany CO:Max-Planck-Institut für Plasmaphysik, Germany CO:U The National Fusion Laboratory, CIEMAT, Madrid, Spain CA2: BA2121

PY - 2014

Y1 - 2014

N2 - The expected threshold power (PL􀀀H) required to access H-mode operation on ITER is extrapolated from a multi-machine scaling that is strongly weighted to a dataset of JET carbon wall discharges [1]. Experiments on JET with the Be/W wall show a minimum in PL􀀀H as function of density and a favorable reduction in the threshold power of 30% at medium to high densities [2]. The carbon wall threshold can be recovered with nitrogen injection. An increase in the threshold power by up to a factor 2 and a reduction of the density at which the minimum occurs was found when the outer strike point position was moved from the horizontal to the vertical target. The existence of a critical min(Er;dia) is consistent with the threshold data from each of the divertor congurations but does not explain the dierences between them. The observation of a strong asymmetry between the inner and outer divertor that develops during a power ramp is correlated with the L-H threshold in the high density branch and indicates a direct eect of the scrape o layer or divertor conditions on the threshold. This mechanism also provides a qualitative explanation for dithering L-H transitions.

AB - The expected threshold power (PL􀀀H) required to access H-mode operation on ITER is extrapolated from a multi-machine scaling that is strongly weighted to a dataset of JET carbon wall discharges [1]. Experiments on JET with the Be/W wall show a minimum in PL􀀀H as function of density and a favorable reduction in the threshold power of 30% at medium to high densities [2]. The carbon wall threshold can be recovered with nitrogen injection. An increase in the threshold power by up to a factor 2 and a reduction of the density at which the minimum occurs was found when the outer strike point position was moved from the horizontal to the vertical target. The existence of a critical min(Er;dia) is consistent with the threshold data from each of the divertor congurations but does not explain the dierences between them. The observation of a strong asymmetry between the inner and outer divertor that develops during a power ramp is correlated with the L-H threshold in the high density branch and indicates a direct eect of the scrape o layer or divertor conditions on the threshold. This mechanism also provides a qualitative explanation for dithering L-H transitions.

M3 - Conference article in proceedings

SP - EX/P5-24

BT - 25th IAEA Fusion Energy Conference

PB - International Atomic Energy Agency IAEA

ER -

Delabie E, Maggi C, Meyer H, Biewer TM, Bourdelle C, Brix M et al. Overview and interpretation of L-H threshold experiments on JET with the ITER-like Wall. In 25th IAEA Fusion Energy Conference: Programme, Abstracts, and Contributions. International Atomic Energy Agency IAEA. 2014. p. EX/P5-24