Name, links and pictures Location Operating Aspect ratio Major radius (m) TF
(tesla)
IP
(MA)
ECH
(MW)
ICH
(MW)
NBI
(MW)
LH
(MW)
Notes and special features
ACST S Korea
Seoul
2000 - 2002 2 0.06 0.02 0.0005 - - - - AC operation. Helicon plasma discharge.
Asperator T-3 Japan
Tohoku
1974 - ? 1.6 0.27 ? 0.1          
BATORM
(BAby TORoidal of Masoud)
Egypt,
Cairo
1998 2 0.06 ? ? - - - - A very small tokamak used for materials testing and tokamak physics studies.
CDX-U
Current Drive Experiment
USA,
Princeton
1993-2004 1.4 0.3 0.23 0.03 - - - - FW heating. Now resurrected as the Lithium Tokamak Experiment, LTX.
CPD
(Compact Plasma wall interaction Device)
Copyright acknowledged
Japan,
Kasuga City
Approx.
2007
1.5 0.3 0.3 0.15 0.2 - - - New spherical tokamak at Kyushu University. Only four TF coils, but they are large enough to give a tolerable ripple (8% at r = 0.5m). Includes a thermal lithium beam diagnostic for 2-D density. Also studying non-inductive start-up using ECRH.
ETE
(Experimento Tokamak Esférico)
Brazil
INPE
2000 1.5 0.3 0.6 0.4 - - - - Limiter machine
Globus-M Russia
IOFFE
2002 1.5 0.36 0.62 0.5 - 1 1.5 - 0.3 second pulses
GLAST
(GLAss Spherical Tokamak)
Copyright acknowledged
Pakistan
Islamabad
? 1.7 0.15 0.4 0.05 - - - - MHP model validation and plasma-wall interactions
GUTTA
at IOFFE
Copyright acknowledged
Russia
St Petersburg State University
1980-1985 2 0.16 1.5 0.15 0.03 - - - Russia's first spherical tokamak.
GUTTA
(at St Petersburg University)
Copyright acknowledged
Russia
St Petersburg State University
2004 2 0.16 1.5 0.15 0.03 - - - Formerly operated at IOFFE Institute. Operations restarted 2004 in St Petersburg State University. Start-up and ECRH studies.
HIST Japan,
Himeji
1998 1.3 0.3 0.2 0.1 - - - -  
HIT2 USA
Seattle
1997-2004 1.5 0.3 0.6 0.37 - - - - Limiter / single null divertor machine to study Coaxial Helicity Injection (CHI).
HSE
(Heidelberg Spheromak Experiment)
Copyright acknowledged
Germany
Heidelberg
1986-1987 1.1 0.08 0.25 0.1 - - - - Heidelberg Spheromak Experiment was converted with an axial conductor to a Spherical Tokamak, and operated in this configuration for only a short time, 1986-7. This was the first spherical tokamak experiment at the several kG and 100 kA level. (Spheromak generated by theta-z-pinch method ( equipped with axial conductor. Full diameter of plasma: 0.3m, length of discharge vessel: 1m, Formation of plasma: ~14-20 microseconds, lifetime of plasma after formation: ~40-50 microseconds, magnetic energy content (in plasma ring): 600 J, electron temperature estimate: 15-20 eV.) Thanks to Hardo Bruhns for this information.
KTM
Kazakh Tokamak for Material studies
Copyright acknowledged
Kazakhstan, Kurchatov 2010 2 0.9 1 0.75   5     Low aspect ratio tokamak for material testing. Will be able to exchange the divertor plates without breaking vacuum. 20 single turn TF coils. Thanks to Alexey Kirilenko for recent information. First plasma September 2010.
LATE
Low Aspect ratio Torus Experiment
Japan, Kyoto University 2005 1.25 0.25 0.12 0.004 0.2       Low aspect ratio spherical tokamak for material testing. Will be able to exchange the divertor plates without breaking vacuum. 20 single turn TF coils.
LTX,
Lithium Tokamak Experiment
Copyright acknowledged
USA,
Princeton
2005 1.5 0.4 0.4 0.4 - - - - Liquid lithium walls. FW heating.
MAST
Mega Amp Spherical Tokamak
Copyright acknowledged Copyright acknowledged
UK, Culham 1999 1.4 0.85 0.5 1.4 1 - 4 - Merging compression technique to drive plasma current, saving solenoid flux.
MAST-U
Mega Amp Spherical Tokamak Upgrade
UK, Culham 2017 1.4 0.85 0.84 1.4 ? - ? - Major upgrade of MAST, with longer pulses, upgraded central column and neutral beam heating, with new 'super-X' divertors.
MEDUSA
(Madison EDUcational Small Aspect ratio)
USA
Madison
1994 - ? 1.5 0.12 0.45 0.04 - - - - Test bed for educational purposes and studies leading to the construction of PEGASUS.
NSST
Next Step Spherical Torus
USA
Princeton
? ? 1.5 2.7 5-10 ? ? ? ? Proposed as the step between today's spherical tokamaks and a large Component Test Facility (CTF). Possibly to use the site that was previously used for TFTR.
NSTX
Copyright acknowledged Copyright acknowledged
US
Princeton
1999-2010 1.32 0.854 0.55 1 - 6 HHFW 7.5 - 1 second + pulses. In 2009, 94.3 Million USD NSTX Upgrade project was started. See NSTX-U
NSTX-U US
Princeton
2015 1.5 0.934 1.0 2.0 - 6 HHFW 15 - The upgrade to the original NSTX increased the size and capability of the centerstack and added a second neutral beam. The construction phase began in October 2011. The NSTX-U first plasma was completed in August 2015 successfully concluding the upgrade project. The first experimental run campaign in the new configuration took place in 2016 with 10 run weeks completed by June 30, 2016.
NUCTE-ST Japan
Nihon University
1998 1.2 0.062 0.45 0.34 ? ? ? ? High elongation machine (10).
PEGASUS USA
Madison
1996 1.1 - 1.2 0.2 - 0.45 0.18 0.1 - 0.3   2     Extremely low aspect ratio tokamak. Double null divertor. EBW heating.
Proto-Sphera Italy
Frascati
Soon ? ? ? ? ? ? ? ? Uses START vacuum vessel.
QUEST
(Q-shu University Experiment with steady-state Spherical Tokamak)
Copyright acknowledged
Japan,
Kasuga City
2008 1.7 0.68 0.25 0.02 ? ? ? ? New spherical tokamak replacing TRIAM-1M. Mission to study issues related to steady-state operation within the All-Japan ST Research Program. In particular, to develop a fully non-inductive current drive scheme that is effective in ST plasmas with high beta and high dielectric constant; to perform integrated studies of recycling and advanced PWI control in steady state, by active control of wall temperature and divertor pumping, and compatibility with high plasma performance; to develop a divertor in ST magnetic configuration which can handle power and particle fluxes in steady state.
Rotamak Australia
Lucas Heights
1987 - 1997 1.1 0.07 0.02 0.003 ? ? ? ? Rotamak with central rod.
Rotamak Australia
Flinders
1998 - 2002 1.6 0.10 0.016 0.012 ? ? ? ? Rotamak with central rod.
SPHEX UK
Manchester
? 1.05 0.23 0.045 0.2         Spheromak, fitted with TF rod in 1991.
ST25
Copyright acknowledged
UK
Culham Innovation Centre then Milton Park
2012 2 0.25 0.2 0.02 0.003 - - - ST25 stands for Spherical Tokamak major radius 25cm. The term 'ST' is marginal - as it has aspect ratio 2, for reasons explained below. It is formed from copper cable TF , solenoid and PF magnets and powered by a 1.5MJ supercapacitor bank; this combination gives the potential for long pulses - 20s to date (as of 2015). Two 3kW continuous wave magnetrons are used to pre-ionise and study EBW (Electron Bernstein Wave) current drive using an inside-launch port. Unusually, the whole table-top device is contained in a small room and powered from only a 32A 415V supply.
Thanks to Alan Sykes of Tokamak Energy for these details.
ST25 HTS
Copyright acknowledged
UK
Milton Park, Abingdon
2015 2 0.25 0.4 (SC) TBA 0.003 - - - A new version of ST25 using high-temperature superconducting coils, built by Tokamak Energy and still under development. The TF coils are cooled to 20K by a cryo-free system. Now claims the world record for the longest duration tokamak plasma at 29 hours, set in July 2015. The discharge was driven by a 600W RF supply but the plasma current has not yet been measured. There is considerable skepticism about this claim - see the records page. Further operation is planned, using a 2.45 GHz heating and current drive system.
START
Copyright acknowledged Copyright acknowledged
UK
Culham
1991-1998 1.25 0.3 0.5 0.31 - - 1 - First 'hot' ST, achieved world record betaT =40%. To ENEA at Frascati, June 2004 to become Proto-Sphera.
STPC-EX Turkey
Ankara
1986 1.5 0.084 0.12 0.0065 - - - -  
SUNIST
Sino UNIted Spherical Tokamak

Copyright acknowledged
China
Beijing
2003 1.3 0.3 0.15 0.05 0.1 ? ? ? Double null divertor / limiter. 0.2MW of EBW heating. ECRH heating system mainly used for pre-ionisation. Currently installing a 0.5 to 1MHz, 100kW, power supply and antenna for Alfven Wave heating and current drive.
TS-3 Japan
Tokyo
1986 1.4 0.2 0.2 0.3 - - - - Limiter machine
TS-4 Japan
Tokyo
2000 1.2 0.55 0.5 0.08 - - - - Limiter machine
TST-2
Tokyo Spherical Tokamak
Japan
Tokyo
1999 1.5 0.38 0.4 0.2 0.2
EBW
- - - Major upgrade of TST-M. Double null divertor / limiter. 0.2 sec pulses. Studying plasma turbulence. Upgrades to heating and current drive systems planned soon.
UTST Japan
Tokyo
2007 1.6 0.39 0.3 0.31 - - 0.7 - Ultra-high beta discharges using the double-null merging method. All PF coils outside the vacuum vessel.