Type Spherical tokamak Major radius ~0.9 m Magnetic field 0.55 T | Operation date 1999–2013 Minor Radius ~0.6 m Heating 5 MW | |
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The Mega Ampere Spherical Tokamak (MAST) experiment was a nuclear fusion experiment in operation at Culham Centre for Fusion Energy, Oxfordshire, United Kingdom from December 1999 to September 2013.
Contents
It followed the highly successful Small Tight Aspect Ratio Tokamak (START) experiment (1991 - 1998) and is followed by MAST-Upgrade (2016 - ), which re-uses many of MAST's components and services. MAST used the same innovative spherical tokamak design as START, which has shown itself to be more efficient than the conventional toroidal design, adopted by Joint European Torus (JET) and ITER. START proved to exceed even the most optimistic predictions and the purpose of MAST is to confirm the results of its forerunner by using a larger more purpose-built experiment.
It was fully commissioned by EURATOM/UKAEA and took two years to design and a further two years to construct. It includes a neutral beam injector similar to that used on START and uses the same merging compression technique instead of the conventional direct induction. Merging compression provides a valuable saving of central solenoid flux, which can then be used to further ramp up the plasma current and/or maintain the required current flat-top.
Its plasma volume is about 8 m3. Density ~ 1020/m3.
Image to right shows plasma in the MAST reactor. Note the almost circular outer profile of the plasma. The extensions off the top and bottom are plasma flowing to the ring divertors, a key feature of modern tokamak designs.
Objectives
Timeline
Design
The magnetic field coils are not superconducting and (for longer runs after upgrade 1a) need to be cooled to -20 °C before each pulse.
Operation
From 1999 to 2013 it made 30471 plasmas (in pulses up to 0.5 sec).
MAST Upgrade
Researchers are carrying out a major upgrade to significantly enhance the devices capabilities to address its primary objectives. (listed above). The first stage "1a" should be complete during 2017. with plasma physics experiments planned towards the end of 2017.
During the first upgrade '1a' :
It will be the first tokamak to use a Super-X divertor.