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A. Sykes representing the START, NBI , MAST and Theory teams
EURATOM / UKAEA Fusion Association, Culham Science Centre, Abingdon, Oxon., OX14 3DB, UK
Abstract. The Spherical Tokamak (ST) is
the low aspect ratio limit of the conventional tokamak, and appears to offer
attractive physics properties in a simpler device. The START (Small Tight
Aspect Ratio Tokamak) experiment provided the world's first demonstration of
the properties of hot plasmas in an ST configuration, and was operational at
Culham from January 1991 to March 1998, obtaining plasma current of up to
300kA and pulse durations of 
50ms. Its successor, MAST is scheduled to
obtain first plasma in Autumn 1998 and is a purpose built, high vacuum machine
designed to have a tenfold increase in plasma volume with plasma currents up
to 2MA. Current drive and heating will be by a combination of
induction-compression as on START, a high-performance central solenoid, 1.5MW
ECRH and 5MW of Neutral Beam Injection. The promising results from START are
reviewed, and the many challenges posed for the next generation of
purpose-built STs (such as MAST) are described.
IAEA 2001
