https://doi.org/10.1007/s100530050038
The influence of mode coupling on the non-linear evolution of tearing modes
1
JET Joint Undertaking, Abingdon, Oxfordshire OX14 3EA, UK
2
Associaço EURATOM/IST, Instituto Superior Tecnico, 1096 Lisboa Codex, Portugal
3
Istituto di Fisica del Plasma del CNR "P. Caldirola", Assoc. EURATOM-ENEA-CNR,
via R. Cozzi 53,
20125 Milan, Italy
Received:
4
May
1999
Revised:
23
July
1999
Published online: 15 February 2000
On the basis of tearing mode theory a simple but physically explicit model of the evolution of toroidally coupled rotating magnetic islands has been developed. The basic mechanism identified by the model in the island evolution is the locking in phase of rotating islands that leads to rapid destabilisation of an initially stable mode. Destabilisation of marginally stable (2, 1) and (3, 1) modes is analysed in several scenarios. It is shown that mode coupling is an effective way of destabilising a m=3 island in a low-β plasma. The numerical examples presented show the individual roles of coupling, inertia and a resistive wall. The model was applied for the analysis of MHD observations of an ASDEX discharge.
PACS: 52.35.Py – Plasma macroinstabilities (hydromagnetic, e.g., kink, fire-hose, mirror, ballooning, tearing, trapped-particle, flute, Rayleigh-Taylor, etc.)
© EDP Sciences, Società Italiana di Fisica, Springer-Verlag, 2000
