Fusion research began with early "pinch" devices in the 1950s that used magnetic fields to contain hot plasma, but evolved into the tokamak design which uses both toroidal and poloidal magnetic fields for stable plasma confinement allowing fusion. The tokamak concept was pioneered in the Soviet Union and breakthroughs were made at Kurchatov Institute, leading tokamaks today include JET, JT-60U, KSTAR and the future ITER reactor. Alternative concepts include the stellarator with a helical magnetic field and inertial confinement fusion using lasers to compress fuel pellets.

1. Fusion devices and the history
of fusion research

2. Early concepts: The pinch device
• Toroidal chamber
enclosing a hot plasma,
with an electric current
‘pinching’ the plasma and
keeping it away from the
wall
• Developed by Peter
Thonemann (Australia)
and Sir George Thomson
(UK)
R=25cm
a=3cm

3. ZETA experiment at Harwell, UK (1950s). USA
and USSR also built early pinch devices
Early concepts: The pinch device

4. The tokamak
• Evolution of the pinch device,
but using two sets of
magnetic field (toroidal and
poloidal) to confine the
plasma, allowing fusion
reactions to take place

5. The tokamak
• Pioneered in the
Soviet Union in the
1950s and 1960s
• Landmark T3 device at
Kurchatov Institute,
Moscow achieved
breakthrough in fusion
performance – 1968
• Joint European Torus
(Culham, UK) now the
largest tokamak
operating (since 1983)

6. EAST – China
KSTAR –
South Korea
Tokamaks past and present
JT-60U –
Japan
JET – Europe
TFTR – U.S.
ASDEX – Germany
DIIID – U.S.
Tore Supra –
France
START – U.K.

7. ITER – the future of tokamaks
• Global project sited in
Cadarache, France
• Forecast to produce net
energy gain of 10
• 500MW output power
• Scheduled to operate
from early 2020s

8. Stellarator
Alternative magnetic fusion concept, dating from
1950s. Similar to tokamak but with helical magnetic
field generated by ‘figure of 8’ shaped coils

9. Stellarator
Difficult to engineer but has more stable plasma.
W 7-X device being built by EU in Greifswald, Germany

10. Inertial confinement fusion (ICF)
Uses lasers to heat and compress pellets of fuel to
induce fusion reactions. Either ‘direct drive’ (laser
fired directly at pellet – a), or ‘indirect drive’ (laser
fired at a cylinder around the pellet – b)

11. Inertial confinement fusion (ICF)
National Ignition Facility (NIF, California, U.S.) –
leading experiments in indirect drive ICF research

12. Cold fusion
• In 1989, Fleischmann and
Pons claimed to have
produced fusion neutrons at
room temperature
• Research not peer-reviewed
and has never been
replicated by other scientists
• Not thought to have been
nuclear fusion – and not
enough heat produced for a
useful source of energy