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Abstract

Several approaches are used at JET to achieve operation at high density with good energy confinement. One of them is the injection of solid fuel pellets to realize efficient particle refuelling by deposition deep inside the plasma column. The new pellet launch system capable of launching from the torus magnetic high field side was investigated for its capability to fulfil this task in conventional ELMy H-mode discharges. Optimized pellet scenarios were developed for plasma configurations with I(P) = 2.5 MA, Bt = 2.4 T, averaged triangularity <delta> approximately equal to 0.34 and mainly neutral beam heating at a level of approximately 17 MW. The accessible operational range was extended by the pellet tool with respect to gas puff refuelling. For example, H-mode conditions could be maintained at densities beyond the Greenwald level. Plasma energy confinement was observed to become density independent at high densities. When avoiding confinement deterioration due to pellet triggered MHD activity or parasitic pellet born gas in appropriate pulse schedules, enhanced particle inventory with more peaked density profiles was achieved while maintaining the plasma pressure profile. First attempts indicate that pellet advantages can be combined with the benefits achieved by higher triangularity. Very high particle refuelling efficiencies were found for pellets injected into `ITER-like' discharges with an upper triangularity <delta{u}> of 0.53.

Additional information

Authors: LANG P T, Max-Planck-Institut für Plasmaphysik, EURATOM Association, Garching (DE);DUX R, Max-Planck-Institut für Plasmaphysik, EURATOM Association, Garching (DE);HAAS G, Max-Planck-Institut für Plasmaphysik, EURATOM Association, Garching (DE);HORTON I D, Max-Planck-Institut für Plasmaphysik, EURATOM Association, Garching (DE);LORENZ A, Max-Planck-Institut für Plasmaphysik, EURATOM Association, Garching (DE);SUTTROP W, Max-Planck-Institut für Plasmaphysik, EURATOM Association, Garching (DE);ALPER B, EURATOM/UKAEA Fusion Association, Culham, Abingdon (GB);CORDEY J G, EURATOM/UKAEA Fusion Association, Culham, Abingdon (GB);FELTON R, EURATOM/UKAEA Fusion Association, Culham, Abingdon (GB);JONES T T C, EURATOM/UKAEA Fusion Association, Culham, Abingdon (GB);LOMAS P J, EURATOM/UKAEA Fusion Association, Culham, Abingdon (GB);STAMP M, EURATOM/UKAEA Fusion Association, Culham, Abingdon (GB);VILLEDIEU E, EURATOM/UKAEA Fusion Association, Culham, Abingdon (GB);WILSON D, EURATOM/UKAEA Fusion Association, Culham, Abingdon (GB);BAYLOR L R, Oak Ridge National Laboratory, Oak Ridge, Tennessee (US);BEURSKENS M, FOM Instituut voor Plasmafysica Rijnhuizen, Nieuwegein (NL);GARZOTTI L, Consorzio RFX, Associatione EURATOM-ENEA sulla Fusione, Padova (IT);JACHMICH S, LPP-ERM/KMS, Association EURATOM-Belgian State, Brussels (BE);ONGENA J, LPP-ERM/KMS, Association EURATOM-Belgian State, Brussels (BE);RAPP J, Institut für Plasmaphysik, Forschungszentrum Jülich (DE);RENK J, Institut für Experimentelle und Angewandte Physik, Universität Regensburg (DE);REICH M, Institut für Experimentelle und Angewandte Physik, Universität Regensburg (DE);SARTORI R, EFDA-CSU, Garching (DE);SCHMIDT G, Princeton Plasma Physics Laboratory, Priceton University (US)
Bibliographic Reference: An article published in: Plasma Physics and Controllled Fusion 44 (September 2002) pp.1919-1928
Availability: This article can be accessed online by subscribers, and can be ordered online by non-subscribers, at: http://stacks.iop.org/0741-3335/44/1919.
Record Number: 200215473 / Last updated on: 2002-11-01
Category: PUBLICATION
Original language: en
Available languages: en