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


    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
    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)


    Conference25th Fusion Energy Conference, IAEA FEC 2014
    Abbreviated titleIAEA FEC 2014
    CountryRussian Federation
    Internet address

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    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, 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 (pp. EX/P5-24). International Atomic Energy Agency IAEA. http://www-naweb.iaea.org/napc/physics/FEC/FEC2014/fec2014-preprints/434_EXP524.pdf