According to Chinese media reports, one of the three largest fusion reactors in operation in the country was able to hold a plasma heated to 70 million °C for more than 17 minutes. This is an important milestone in the development of fusion energy production. The long-term operation of the pilot plant allows the process control systems to be fine-tuned which will eventually help to develop a commercial version of the reactor.
The Experimental Advanced Superconducting Tokamak (EAST, HT-7U tokamak) located in Hefei, Anhui province, boasted a personal record for keeping the plasma burning process in check. Earlier last May, this reactor set another record - it held a plasma heated to 120 million °C for 101 seconds. But that was not all. At the time, the EAST reactor was able to hold plasma at 160 million °C for 20 seconds. The new record was set for the longest sustained combustion at the relatively high temperature of 70 million °C, a process that lasted 1056 seconds (17:36).
The first EAST was launched in 2006. It is based on a modified HT-7 reactor, which was commissioned according to a Russian design in the early 1990s. The EAST reactor participates in a scientific programme to prepare for the launch of the ITER (International Experimental Reactor).
It should be made clear that the record temperatures reached are most likely due to the heating of electrons in the plasma torch. Sources do not specify this point. To achieve a stable fusion reaction in plasma, it is necessary to heat ions to 100 million °C, and they are heavier than electrons, and therefore about twice as cold at equal energy costs. For example, the South Korean KSTAR reactor sets clear records for heating ions in plasma. Its most recent record is for heating ions to 100 million °C for 30 seconds. China has not disclosed these figures. It is very likely that this is the temperature of the electrons in the plasma (the figures are bigger and look prettier).
Scientists have high hopes for the new tokamak HL-2M Tokamak. This facility was commissioned only recently, at the end of last year. But the Tokamak has already proven itself, holding plasma heated to 150 million degrees Celsius for about 10 seconds. The potential Chengdu-based HL-2M tokamak can heat electrons to 200 million °C and ions to 100 million °C. This year we are sure to hear about records set at the facility.