IT10 · On Ion Cyclotron Current Drive for sawtooth control

L.-G. Eriksson1, T. Johnson2, M.-L. Mayoral3, S. Coda4, O. Sauter4, R.J. Buttery5, D. McDonald3, T. Hellsten2, M.J. Mantsinen5, A. Mueck4, J.-M. Noterdaeme6,7, M. Santala3, E. Westerhof8, P. de Vries3 and JET-EFDA contributors*

1Association EURATOM-CEA, CEA/DSM/DRFC, CEA-Cadarache, St. Paul lez Durance, France
2Association Euratom-VR, KTH, SE-100 44 Stockholm, Sweden
3UKAEA/Euratom Fusion Association, Culham, Science Centre, OX14 3DB, Abingdon, United Kingdom
4EURATOM Confédération Suisse, CRPP-EPFL, Lausanne, Switzerland
5Helsinki University of Technology, Association Euratom-Tekes, Finland
6Max-Planck IPP-EURATOM Assoziation, Garching, Germany
7Gent University, Department EESA, Belgium
8FOM-Institute for Plasma Physics Rijnhuizen, Association EURATOM-FOM, Trilaterial Euregio Cluster, The Netherlands,
*See the appendix of J. Pamela et al., Nuclear Fusion, 45 S63-S85, 2005.

Abstract: Experiments using Ion Cyclotron Current Drive (ICCD) to control sawteeth are presented. In particular, discharges demonstrating shortening of fast ion induced long sawteeth reported in [L.-G. Eriksson et al., Physical Review Letters 92, 235004 (2004)] by ICCD have been analysed in detail. Numerical simulations of the ICCD driven currents are shown to be consistent with the experimental observations. They support the hypothesis that an increase of the magnetic shear, due to the driven current, at the surface where the safety factor is unity was the critical factor for the shortening of the sawteeth. In view of the potential utility of ICCD, the mechanisms for the current drive have been further investigated experimentally. This includes the influence of the averaged energy of the resonating ions carrying the current and the spectrum of the launched waves. The results of these experiments are discussed in the light of theoretical considerations.

Note: In special issue in Nuclear Fusion - volume 46, issue 10

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