| 词条 | Mega Ampere Spherical Tokamak |
| 释义 |
|name = MAST |image = MAST_plasma_image.jpg |imagetitle = Plasma in the MAST reactor. |type = Spherical tokamak |operation = 1999–2013 |major radius = ~0.9 m |minor radius = ~0.6 m |field = 0.55 T |heating = 5 MW |current = 1.3 MA |location = Culham, Oxfordshire, United Kingdom }} The Mega Ampere Spherical Tokamak (MAST) experiment was a nuclear fusion experiment in operation at Culham Centre for Fusion Energy, Oxfordshire, England, from December 1999 to September 2013. 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. It confined plasmas with densities on the order of 1020/m3. Image to right shows plasma in the MAST reactor, displaying its almost circular outer profile. The extensions off the top and bottom are plasma flowing to the ring divertors, a key feature of modern tokamak designs. Objectives
Timeline
DesignThe magnetic field coils are not superconducting and (for longer runs after upgrade 1a) need to be cooled to -20 °C before each pulse.[2] OperationFrom 1999 to 2013 it made 30471 plasmas (in pulses up to 0.5 sec). Research by Melanie Windridge et al during this period demonstrated non-linear instability at large vertical displacements in the MAST tokamak. Windridge concluded that MAST plasmas may be more vulnerable to vertical disruptions than other tokamaks because of the magnetic field structure and the lack of a close-fitting wall.[3] MAST UpgradeResearchers are carrying out a major upgrade to significantly enhance the device's capabilities in an attempt to address its primary objectives. The first stage "1a" should be completed during 2017.[4] with plasma physics experiments planned for 2019.[5][6] During the first upgrade '1a' :
It will be the first tokamak to use a Super-X divertor. See also
References1. ^{{cite web|url=http://www.ccfe.ac.uk/news_detail.aspx?id=239 |title=News: It's goodbye to MAST - and hello to MAST Upgrade |publisher=Ccfe.ac.uk |date= |accessdate=2015-12-11}} 2. ^{{cite web|url=http://www.ccfe.ac.uk/mastupgrade_model.aspx |title=MAST Upgrade: MAST Upgrade model |publisher=Ccfe.ac.uk |date= |accessdate=2015-12-11}} 3. ^{{cite journal|last1=Windridge|first1=M. J.|last2=Cunningham|first2=G.|last3=Hender|first3=T. C.|last4=Khayrutdinov|first4=R.|last5=Lukash|first5=V.|title=Non-linear instability at large vertical displacements in the MAST tokamak|journal=Plasma Physics and Controlled Fusion|date=2011|volume=53|issue=3|pages=035018|doi=10.1088/0741-3335/53/3/035018|language=en|issn=0741-3335|bibcode=2011PPCF...53c5018W}} 4. ^{{cite web|url=http://www.ccfe.ac.uk/mast_upgrade_project.aspx |title=Research: MAST Upgrade |publisher=Ccfe.ac.uk |date= |accessdate=2015-12-11}} 5. ^{{cite web|url=http://www.ccfe.ac.uk/mast_upgrade_news.aspx |title=MAST Upgrade: MAST Upgrade news |publisher=Ccfe.ac.uk |date= |accessdate=2015-12-11}} 6. ^{{cite web|url=http://www.ccfe.ac.uk/mast_upgrade_project.aspx |title = Research: MAST Upgrade |publisher=Culham Centre for Fusion Energy |date= |accessdate=2018-12-09 | quote = MAST Upgrade will be implemented in three stages. Funding has been agreed with the Engineering and Physical Sciences Research Council for the core upgrade (Stage 1a), which will be ready for plasma operations in 2019. Two additional phases (Stage 1b and Stage 2) will follow in later years subject to funding.}} External links
5 : Fusion power|Fusion reactors|Plasma physics|Research institutes in Oxfordshire|Tokamaks |
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