The Mega Amp Spherical Tokamak

Results from START at Culham have been very impressive and have triggered the construction of several new Spherical Tokamaks (R/a≤1.5), including the Mega Amp Spherical Tokamak (MAST), which was given EURATOM approval in April 1996. MAST (R=0.7 m, a=0.5 m, k∼2, Ip≤2 MA) is twice the size of START and will allow plasmas with cross-section similar to medium-sized conventional tokamaks (e.g. ASDEX-U, D-IIID) to be studied. A summary is presented of the overall design of MAST, which as far as possible has been based on the successful approach used on START and has been arranged to maximise the use of existing COMPASS power supplies. Details of some of the challenging design issues associated with the components in the central regions of the machine, where space is restricted, are described.