Aachen PK 2003 – scientific programme
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P: Plasmaphysik
P 5: Basic Plasma Physics, Theory
P 5.1: Talk
Tuesday, March 18, 2003, 11:30–11:50, FO1
SAWTEETH ON MAST: — •Gianpaolo Turri1, Richard Buttery1, Steve Cowley2, Jim Hastie1, and Chris Gimblett1 — 1UKAEA Fusion, Culham Science Centre, Abingdon, Oxon., OX14 3DB, U.K. — 2Imperial College of Science, Technology and Medicine, London, SW7 2AZ
The sawtooth instability is a key unresolved problem of tokamak plasma physics. Although often modelled as Kadomtsev-type full reconnection, hence removing the q=1 surface, various experiments have shown that this surface is preserved in the plasma. Sawteeth are important not only because they reduce confinement, but also because they can trigger other more serious modes in the plasma. Recent results from MAST show that q=1 is also preserved in some cases in the Spherical Tokamak, with the observation of resilient 1/1 snakes during sawtooth oscillations. These data are being used to explore alternate sawtooth models such as that of Gimblett-Hastie [Plas. Phys. Control. Fus. 36 p1439], based on the resistive interchange instability. Analysis has shown that the core is resistive interchange unstable during the ramp up of every sawtooth, becoming stabilised just after the crash when the pressure profile becomes slightly hollow. Detailed analysis of sawteeth, both with and without snakes, will be presented in the paper. [Work jointly funded by the UK Dept Trade and Industry and EURATOM].