Community Research and Development Information Service - CORDIS

Abstract

A new scenario to delay or prevent neoclassical tearing mode (NTM) onset is presented. By active sawtooth destabilisation, short period and low amplitude sawteeth are generated, such that the sawtooth produced NTM seed island is reduced and the threshold normalised plasma pressure for triggering of NTMs, Beta(Nonset), is increased. The scenario has been explored experimentally in the Joint European Torus (JET). Ion cyclotron resonance frequency (ICRF) waves tuned to the 2nd harmonic H-minority resonance have been used for sawtooth control. Whereas ICRF waves generally induce sawtooth stabilisation, favouring the triggering of NTMs and reducing Beta(Nonset), the present experiments show that by toroidally directed waves, ion cyclotron current drive is produced, and that sawteeth can be destabilised by careful positioning of the 2nd harmonic H resonance layer with respect to the sawtooth inversion radius. As a result, NTM onset is delayed and Beta(Nonset) is increased above its value obtained in discharges with additional heating from neutral beam injection alone.

Additional information

Authors: WESTERHOF E, FOM-Rijnhuizen, Association EURATOM-FOM, Nieuwegein (NL);SAUTER O, Centre de Recherches en Physique des Plasmas, Association EURATOM-Confédération Suisse, EPFL, Lausanne (CH);ANGIONI C, Centre de Recherches en Physique des Plasmas, Association EURATOM-Confédération Suisse, EPFL, Lausanne (CH);MAYORAL M L ET AL, Euratom/UKAEA Fusion Association, Culham Science Centre, Abingdon (GB);MANTSINEN M J, Helsinki University of Technology, Association Euratom-Tekes (FI);NAVE M F F, Centro de Fusao Nuclear, Ass. Euratom/IST, Instituto Superior Tecnico, Lisboa (PT);BELO P, Centro de Fusao Nuclear, Ass. Euratom/IST, Instituto Superior Tecnico, Lisboa (PT);HELLSTEN T, EFDA-JET CSU, Culham Science Centre, Abingdon (GB): Euratom-VR Association, Swedish Research Council, Stockholm (SE);JOHNSON T, LPP-ERM/KMS, Association Euratom-Belgian State, Brussels (BE);LAMALLE P, Max-Planck-Institut für Plasmaphysik, IPP-Euratom Assoziation, Garching (DE);MARASCHEK M E, Association EURATOM-CEA, CEA/DSM/DRFC, CEA-Cadarache, St Paul-lez-Durance (FR);NGUYEN F, Associazione EURATOM-ENEA sulla Fusione, Centro Ricerche Frascati, Rome (IT);PÉQUET A L, Associazione EURATOM-ENEA sulla Fusione, Centro Ricerche Frascati, Rome (IT);ZABIEGO M, Associazione EURATOM-ENEA sulla Fusione, Centro Ricerche Frascati, Rome (IT);PODDA S, Institut für Plasmaphysik, Forschungszentrum Jülich GmbH, EURATOM Association, Trilateral Euregio Cluster, Jülich (DE);RAPP J,
Bibliographic Reference: An article published in: Nuclear Fusion 42 (November 2002) 1324-1334
Availability: This article can be accessed online by subscribers, and can be ordered online by non-subscribers, at: http://stacks.iop.org/0029-5515/42/1324
Follow us on: RSS Facebook Twitter YouTube Managed by the EU Publications Office Top