KSTAR, known as an artificial sun because it performs the same nuclear fusion reaction as the sun, was completed in 2007 and achieved the first plasma generation in 2008. KSTAR is about a third the size of ITER, a large experimental reactor under construction in France. Both reactors are tokamaks: devices for nuclear fusion in a ring device that heats electrified gases to extremely high temperatures and pressures.
The deflector used by KSTAR is located at the bottom of the tokamak and manages the reactor's exhaust emissions and impurities. The deflector is the part that comes into contact with the plasma, meaning that it sits inside the tokamak and is subjected to the full heat of the internal surface. Currently, KSTAR is capable of plasma operation for about 30 seconds; Scientists hope the new deflector will allow the plasma operation time to reach 300 seconds by the end of 2026.
KSTAR originally had a carbon deflector, but in 2018, scientists began working on a tungsten deflector for tokamaks. Tungsten has a higher melting point than carbon, and according to a recent release by South Korea's National Science and Technology Research Council, it doubles the reactor's heat flux limit. The prototype of the new deflector was completed in 2021 and the installation was completed last year. "In KSTAR, we have adopted a tungsten material deflector of the same choice as ITER," said Suk Jae Yoo, director of the Korea Institute of Fusion Energy, in the release. "We will do everything we can to obtain the data needed by ITER through the KSTAR experiment. ”
ITER expects to achieve the first plasma generation in 2025, with the first fusion planned for 2035. But the reactor timeline has been delayed, and the cost has increased from about 5 billion euros in 2006 to more than 20 billion euros, so we may have to wait even longer.
Still, this is an exhilarating time for the tokamak reactor. Last month, Japan's six-story JT-60SA reactor was commissioned; Researchers associated with the project estimate that the reactor will take two years to develop the plasma needed for the experiment. According to the International Atomic Energy Agency, there are currently more than 50 tokamaks in operation around the world.