The JT-60SA tokamak—a joint program of fusion research and development agreed and co-financed by the European Atomic Energy Community (Euratom) and the government of Japan—entered its integrated commissioning phase in late 2020, after a six-year project to modify and modernize the existing JT-60U tokamak at the Naka Fusion Institute in Japan.
During the step-by-step integrated commissioning process, the air was first evacuated from the vacuum vessel and surrounding cryostat before the device's superconducting magnets were slowly cooled to the temperature of 4 K (- 269 °C). Next, the vacuum vessel was "baked" to 200 °C to rid it of moisture and any possible residual contaminants. Finally the magnets were energized—first independently and then as a full group.
In March 2021, during the coil energization test of poloidal field coil EF1, feeder joints were damaged. Experts from both Japan and Europe investigated the cause of the damage and determined that the joints of the EF1 feeders needed to be reinforced with greater insulation.
Repairs will be carried out on the incriminated joints and others to prevent recurrence of the incident. Once the repairs and improvements are completed, EF1 will undergo further testing to determine that it can withstand even worst-case conditions and ensure that it is ready for operation.
JT-60SA integrated commissioning is expected to resume in February 2022.
Find out more on the JT-60SA website.
This story was originally published by our partner ITER.