In Daejeon, News1 reporter Kim Tae-jin reports that a domestic research team has elucidated the origin of ‘runaway electrons,’ which is one of the critical challenges in designing safe commercial fusion reactors, drawing significant attention.
The National Research Foundation of Korea announced on the 28th that Professor Na Yong-su’s team from Seoul National University’s Department of Nuclear Engineering has identified the formation principle of runaway electrons that occur when starting up a fusion reactor tokamak.
Nuclear fusion power generation involves creating a tokamak, an artificial sun device that uses a magnetic field inside a donut-shaped device to enable the movement of plasma particles, and using raw materials obtained from seawater to create a nuclear fusion reaction that produces clean energy.
To trigger a nuclear fusion reaction in a tokamak, high-temperature plasma must first be generated, which is referred to as ignition. A strong electric field, similar to the principle of lightning, is necessary for tokamak ignition, but this electric field poses the issue of producing runaway electrons.
Runaway electrons are high-energy electrons that continuously receive energy from a strong electric field and cannot have their acceleration suppressed. They can hinder plasma formation by depleting the energy applied externally to form the plasma and can cause critical damage to the device.
Therefore, for the commercialization of tokamaks, it is essential to elucidate the formation principle of runaway electrons and develop technology that can accurately predict their occurrence.
To address this, the research team collaborated with Germany’s Max Planck Institute and the International Thermonuclear Experimental Reactor (ITER) organization to generalize the dynamics theory that describes runaway electrons, identifying a new mechanism of their occurrence and resolving the theoretical bottleneck in the ignition design for commercial fusion reactors.
Furthermore, they revealed that some electrons that do not undergo inelastic interactions with hydrogen atoms during tokamak ignition significantly contribute to the formation of runaway electrons. They generalized electron dynamics theory and validated predictions that contrasted with classical models to elucidate this.
Professor Na Yong-su remarked, “This research outcome provides an accurate formation rate of runaway electrons, which is expected to aid in the ignition design not only for the Korean demonstration reactor and commercial reactors but also for the ITER, in which Korea, the EU, the US, Japan, Russia, China, and India are participating.”
This research, conducted with support from the leading research center as part of a group research project promoted by the Ministry of Science and ICT and the National Research Foundation of Korea, was published online on the 24th of last month in the international journal ‘Physical Review Letters.’