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Return To: Session EX/S1 - Stability and High Beta
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(EX/S1-2) Sawtooth, Neo-Classical Tearing Mode and Error Field Studies in JET

T.C. Hender1), O. Sauter2), B. Alper1), C. Angioni2), M.R. de Baar3)1), M. De Benedetti4), P. Belo5), M. Bigi1), D.N. Borba5)6), T. Bolzonella7), R. Budny8), R.J. Buttery1), A. Gondhalekar1), N.N. Gorelenkov8), A. Gude9), S. Guenter9), T. Hellsten10)6), D.F. Howell1), R. Koslowki11), R.J. La Haye12), A.W. Hyatt12), P. Lamalle13)6), E. Lazzaro14), M.J. Mantsinen15), M. Maraschek9), M.L. Mayoral1), K.G. McClements1), F. Milani1), F. Nabais5), M.F.F. Nave5), F. Nguyen16), S. Nowak14), A.-L. Pecquet16), C. Perez11), C.C. Petty12), S.D. Pinches9), A. Pochelon2), S. Podda4), J. Rapp11)6), F Salzedas5), F Sartori1), S.E. Sharapov1), M. Stamp1), D. Testa17)2), E. Westerhof3), P.C. de Vries3), P. Zanca7), JET EFDA Contributors
1) EURATOM/UKAEA Fusion Association, Culham Science Centre, Abingdon, United Kingdom
2) CRPP, Assoc. Euratom-Confédération Suisse, École Polytechnique Fédérale de Lausanne (EPFL), Switzerland
3) FOM-Rijnhuizen, Assoc. Euratom-FOM, Nieuwegein, Netherlands
4) CRE ENEA, Assoc. EURATOM-ENEA, Frascati, Italy
5) Assoc. Euratom/IST, Centro de Fusão Nuclear, Lisboa, Portugal
6) EFDA-JET CSU, Culham Science Centre, Abingdon, Oxfordshire, UK
7) Consorzio RFX Assoc. Euratom-ENEA-CNR, Padova, Italy
8) Princeton Plasma Physics Laboratory, Princeton, NJ, USA
9) IPP-Euratom Assoziation, Garching, Germany
10) KTH Assoc. Euratom/NFR, Stockholm, Sweden
11) Forschungszentrum Jülich GmbH, Assoc. EURATOM-FZ Jülich, Jülich, Germany
12) General Atomics, San Diego, USA
13) ERM/KMS, Euratom-Belgian State Assoc. Brussels, Belgium
14) IFP CNR Assoc. Euratom-ENEA-CNR, Milan, Italy
15) Helsinki University of Technology, Association Euratom-Tekes, Finland
16) Association Euratom-CEA sur la Fusion Contrôlée, Cadarache, France
17) Plasma Science and Fusion Center, Massachusetts Institute of Technology, Boston, USA

Abstract.  A range of ITER relevant plasma stability issues have been studied in the JET tokamak; these include the effects of fast particles on sawteeth, control of NTMs via sawteeth seeds, scaling of (2,1) NTM thresholds and the effect of error fields on plasma rotation and vice-versa. The sawtooth studies have examined both the effects of ICRF and NBI fast particles, and models used for ITER predictions have been validated. Large sawteeth, due to fast particle stabilisation, have been shown to trigger m=3, n=2 NTMs at low beta. Conversely the use of ICCD to produce small short period sawteeth has been shown to raise the NTM beta-limit, suggesting the value of local current drive near q=1. The m=2, n=1 NTM, which when destabilised results in severe degradation of plasma performance, has been studied in a joint scaling experiment with the DIII-D tokamak. These experiments using closely matched non-dimensional parameters (plasma shape, R/a, q, gyro-radius and collisionality) on DIII-D and JET show similar NTM beta-limits and consistent scalings. The issue of error field thresholds and their variation with plasma rotation has also been studied, helping to clarify scalings to ITER.

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IAEA 2003