The Massachusetts Institute of Technology's (MIT’s) Alcator C-Mod tokamak nuclear fusion reactor on 30 September set a new world record for plasma pressure of 2.05 atmospheres. This is 16% better than the previous record of 1.77 atmospheres set at the same facility in 2005 at a temperature of 35m Celsius and lasting for two seconds. The breakthrough was presented on 17 September at the International Atomic Energy Agency’s fusion summit in Japan. Professor Robert McCrory of the University of Rochester, New York, said the result confirms that the high pressures required for burning plasma can be best achieved with high-magnetic-field tokamaks such as Alcator C-Mod.

MIT said the world record was achieved on the last day of the tokamak’s operation, because funding from the US Department of Energy has now ended. The US, along with the EU, China, India, South Korea, Russia and Japan, are currently putting their fusion funding into the €15bn ($17bn) International Thermonuclear Experimental Reactor (Iter), a tokamak under construction in France. Iter will be approximately 800 times larger in volume than Alcator C-Mod, but it will operate at a lower magnetic field. Iter is expected to reach 2.6 atmospheres when in full operation by 2032.