Sawtooth control in fusion plasmas
Graves, J P; Angioni, C; Budny, R V; Buttery, R J; Coda, S; Eriksson, L-G; Gimblett, C G; Goodman, T P; Hastie, R J; Henderson, M A; Koslowski, H R; Mantsinen, M J; Martynov, An; Mayoral, M-L; Mück, A; Nave, M F F; Sauter, O; Westerhof, E; Graves, J P; Centre de Recherches en Physique des Plasmas, Association EURATOM—Confédération Suisse, EPFL, 1015 Lausanne, Switzerland; Angioni, C; MPI für Plasmaphysik, EURATOM—Association, D-85748 Garching, Germany; Budny, R V; Princeton Plasma Physics Laboratory, Princeton, NJ 08543, USA; Buttery, R J; Euratom/UKAEA Fusion Association, Culham Science Centre, Abingdon, Oxon OX14 3DB, UK; Coda, S; Centre de Recherches en Physique des Plasmas, Association EURATOM—Confédération Suisse, EPFL, 1015 Lausanne, Switzerland; Eriksson, L-G; Association EURATOM-CEA, CEA/DSM/DRFC, CEA-Cadarache, F-13108 St. Paul lez Durance, France; Gimblett, C G; Euratom/UKAEA Fusion Association, Culham Science Centre, Abingdon, Oxon OX14 3DB, UK; Goodman, T P; Centre de Recherches en Physique des Plasmas, Association EURATOM—Confédération Suisse, EPFL, 1015 Lausanne, Switzerland; Hastie, R J; Euratom/UKAEA Fusion Association, Culham Science Centre, Abingdon, Oxon OX14 3DB, UK; Henderson, M A; Centre de Recherches en Physique des Plasmas, Association EURATOM—Confédération Suisse, EPFL, 1015 Lausanne, Switzerland; Koslowski, H R; Association EURATOM-FZ-Juelich, Institut fuer Plasmaphysik, Trilateral Euregio Cluster, D-52425 Juelich, Germany; Mantsinen, M J; Association Euratom—Tekes, Helsinki University of Technology, Finland; Martynov, An; Centre de Recherches en Physique des Plasmas, Association EURATOM—Confédération Suisse, EPFL, 1015 Lausanne, Switzerland; Mayoral, M-L; Euratom/UKAEA Fusion Association, Culham Science Centre, Abingdon, Oxon OX14 3DB, UK; Mück, A; Centre de Recherches en Physique des Plasmas, Association EURATOM—Confédération Suisse, EPFL, 1015 Lausanne, Switzerland; Nave, M F F; Associação EURATOM/IST, Centro de Fusão Nuclear, Lisbon, Portugal; Sauter, O; Centre de Recherches en Physique des Plasmas, Association EURATOM—Confédération Suisse, EPFL, 1015 Lausanne, Switzerland; Westerhof, E; FOM—Institute for Plasma Physics Rijnhuizen, Association EURATOM-FOM, Trilateral Euregio Cluster, The Netherlands; , ;
Журнал:
Plasma Physics and Controlled Fusion
Дата:
2005-12-01
Аннотация:
Clear observations of early triggering of neo-classical tearing modes by sawteeth with long quiescent periods have motivated recent efforts to control, and in particular destabilize, sawteeth. One successful approach explored in TCV utilizes electron cyclotron heating in order to locally increase the current penetration time in the core. The latter is also achieved in various machines by depositing electron cyclotron current drive or ion cyclotron current drive close to the q = 1 rational surface. Crucially, localized current drive also succeeds in destabilizing sawteeth which are otherwise stabilized by a co-existing population of energetic trapped ions in the core. In addition, a recent reversed toroidal field campaign at JET demonstrates that counter-neutral beam injection (NBI) results in shorter sawtooth periods than in the Ohmic regime. The clear dependence of the sawtooth period on the NBI heating power and the direction of injection also manifests itself in terms of the toroidal plasma rotation, which consequently requires consideration in the theoretical interpretation of the experiments. Another feature of NBI, expected to be especially evident in the negative ion based neutral beam injection (NNBI) heating planned for ITER, is the parallel velocity asymmetry of the fast ion population. It is predicted that a finite orbit effect of asymmetrically distributed circulating ions could strongly modify sawtooth stability. Furthermore, NNBI driven current with non-monotonic profile could significantly slow down the evolution of the safety factor in the core, thereby delaying sawteeth.
838.3Кб