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Abstract

We present results obtained from modelling the septum assessment experiments of the JET MkIIGB divertor with the B2-Eirene code package. Similar L-mode discharges have been performed with and without septum, varying density and gas puffing location. High and low inner wall clearance simulations are also compared, as this parameter has been shown experimentally to play an important role in the final density limit. According to the simulations, the neutrals ionization pattern is not affected by the septum, consistent with experiment. The septum does improve the pumped particle flux in the outer divertor, the inner divertor results depending on plasma-wall clearance, but this only concerns a small fraction of the recycling flux at the targets (less than 2%) and does not influence the overall divertor plasma very much. Comparison between inner and outer gas fuelling with a moderate gas puff rate shows no difference in the simulations without septum, while a slight asymmetry is observed in the simulations with septum, showing that the septum allows acting separately on the inner and outer divertor. We conclude that a neutral flow exists linking outer and inner divertors with particles travelling around the plasma in the main chamber.

Additional information

Authors: TSITRONE E, Association EURATOM-CEA, CEA Cadarache, St-Paul-lez-Durance (FR);BONNIN X, Association EURATOM-CEA, CEA Cadarache, St-Paul-lez-Durance (FR);GHENDRIH P, Association EURATOM-CEA, CEA Cadarache, St-Paul-lez-Durance (FR);ANDREW P ET AL, Euratom/UKAEA Fusion Association, Culham Science Centre, Abingdon (GB);COSTER D, Max-Planck-Institut fur Plasmaphysik, IPP Euratom Assoziation, Garching (DE);JACHMICH S, LPP, ERM/KMS, Association Euratom-Belgian state, Brussels (BE);KUKUSHKIN A, ITER JCT, Garching JWS, Garching (DE);LOARTE A, EFDA CSU Garching, Max-Planck-Institut fiir Plasmaphysik, Garching (DE);PITTS R, CRPP, Association Euratom-Confederation Suisse, EPFL, Lausanne (CH);WISCHMEIER M, CRPP, Association Euratom-Confederation Suisse, EPFL, Lausanne (CH);RAPP J, EFDA-JET CSU, Culham Science Centre, Abingdon (GB);HUBER A, Institut fiir Plasmaphysik, Forschungszentrum Jülich, Euratom Association, Jülich (DE);REITER D, Institut fiir Plasmaphysik, Forschungszentrum Jülich, Euratom Association, Jülich (DE)
Bibliographic Reference: An oral paper given at: 9th Plasma Edge Theory Meeting Held at: San Diego, California, USA, September 3-5, 2003
Availability: Available from Association EURATOM-CEA, Département de Recherches sur la Fusion Contrôlée, CEA Cadarache, F-13108 St Paul-Lez-Durance, France Tel:+33-4-42257001; Fax:+33-4-42256421 E-mail: dirdrfc@drfc.cad.cea.fr
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