Japan last week started up its new JT-60SA, the world’s largest active fusion reactor. This achievement “demonstrates to the world that the machine fulfills its basic function,” Sam Davis, project manager for Fusion for Energy, an EU organization that collaborates with Japan’s National Institutes of Quantum Science and Technology (QST), told Science. According to Hiroshi Shirai, project manager for QST, it will be another two years before the new reactor is ready for meaningful physical experiments.
The JT-60SA is the result of an agreement between the European Union and Japan in return for agreeing to ITER’s eventual installation in France. The reactor is 15.5 meters high, half the height of ITER, and can hold 135 cubic meters of plasma, a volume similar to that of a train tank car. The Japanese reactor will use hydrogen and its isotope deuterium, but not tritium, a form of hydrogen widely used in such systems that is expensive, scarce and radioactive.
The experiments carried out with the plasma in the JT-60SA will allow researchers to study its stability and effect on energy production, something that Alberto Loarte, head of ITER’s scientific division, says will be applied to the massive reactor located in France. The ambitious ITER nuclear fusion reactor project already exceeds its original budget by billions of euros and is decades behind schedule.