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Abstract

A campaign of pure helium discharges in the JET tokamak equipped with the MarkIIGB diverter has been performed. This paper describes some of the experimental observations of diverter detachment obtained in L-mode density ramp He discharges and presents a selection of results from the application of B2.5-Eirene code modelling to a JET He plasma. Detachment is very different from that observed in equivalent D discharges. Particle fluxes remain attached up to higher densities and, with decreasing input power, particle detachment occurs earlier in density. However, in contrast to comparable D plasmas, the low measured target T(e) at all but the lowest n(e) in helium leads to an earlier decrease in power flux. Simulations show that detachment is caused by the escape of He neutrals from the target vicinity where, together with the He{+} ions they radiate along the separatrix and above the X-point area, starving regions downstream of power.

This was originally an oral paper presented at the 15th International Conference on Plasma Surface Interactions in Controlled Fusion Devices (PSI-15), organised by the National Institute for Fusion Science, Japan, and held at Gifu, Japan, May 27-31, 2002

Additional information

Authors: WISCHMEIER M, Centre de Recherches en Physique des Plasmas, Association EURATOM-Confédération Suisse, Ecole Polytechnique Fédérale de Lausanne (CH);PITTS A, Centre de Recherches en Physique des Plasmas, Association EURATOM-Confédération Suisse, Ecole Polytechnique Fédérale de Lausanne (CH);COSTER D, Max-Planck-Institut für Plasmaphysik, EURATOM-Association, Garching (DE);EICH T, Max-Planck-Institut für Plasmaphysik, EURATOM-Association, Garching (DE);BONIN X, Max-Planck-Institut für Plasmaphysik, EURATOM-Association, Griefswald (DE);HUBER D, FZJ-Forschungszentrum Jülich, Association Euratom-FZJ, Jülich (DE);JACHMICH S, FZJ-Forschungszentrum Jülich, Association Euratom-FZJ, Jülich (DE);INGESSON L C, FOM-Inst. Plasmafysica, Association Euratom-FOM, Nieuwegein (NL);KUKUSHLIN A, ITER International Team, Garching (DE);LOARTE A, EFDA-CSU, Max-Planck-Institut für Plasmaphysik, Garching (DE);MATTHEWS G F, Euratom-UKAEA Fusion Association, Culham Science Center, Abingdon (GB);TSITRONE E, Association EURATOM-CEA Cadarache, Saint-Paul-Lez-Durance (FR)
Bibliographic Reference: An article published in: Journal of Nuclear Materials, Vols 313-316, March 2003, pp. 980-985 It can be accessed online by subscribers, or ordered online by non-subscribers, at: http://dx.doi.org/10.1016/S0022-3115%2802%2901427-7
Availability: The original oral paper is included in report LRP 727/02, available free from: École Polytechnique Fédérale de Lausanne, Ecublens, CH-1015 Lausanne, Fax +41-21-693474
ISBN: ISSN: 0458-5895
Record Number: 200215184 / Last updated on: 2003-10-21
Category: PUBLICATION
Original language: en
Available languages: en