An experiment run at Seoul National University in South Korea has simultaneously achieved heat and stability levels close to a viable fusion reactor
Recently, a Korean nuclear fusion reactor successfully reached and sustained a temperature of 100 million degrees Celsius for 30 seconds. The simultaneous attainment of heat and stability, once the technology can be scaled up, moves us closer to a workable fusion reactor, even though the duration and temperature alone are not absolute records.
To keep the plasma contained, scientists typically use magnetic fields of various forms. One technique is the edge transport barrier (ETB), which shapes plasma through a sharp pressure cut-off close to the reactor wall, preventing heat and plasma from escaping. The internal transport barrier (ITB), which generates higher pressure closer to the plasma’s center, is another frequently used method.
At the Korea Superconducting Tokamak Advanced Research (KSTAR) device, Yong-Su Na from Seoul National University in South Korea and his colleagues employed a modified ITB approach to achieve a significantly lower plasma density and higher stability. The strategy used by Na appears to increase plasma core temperatures while lowering plasma edge temperatures, which will likely increase the lifespan of reactor components. According to Na, the highly energetic ions at the plasma’s core, the so-called fast-ion-regulated enhancement (FIRE), are crucial for achieving stability. The achieved low density was a vital element, as well.
Only due to hardware constraints was the reaction terminated after 30 seconds; greater times should be feasible going forward. KSTAR has now been shut down for improvements, and Na claims that replacing the carbon in the reactor’s wall with tungsten will increase experiment reproducibility.
Despite the excitement this significant accomplishment has generated, other engineering challenges must be faced, such as how to scale to larger devices, before a functional power plant can be constructed. Creating techniques to remove heat from the reactor and use it to produce electrical current will be a part of that. In truth, the remaining scientific obstacles in fusion power research should be surmountable, but commercializing this technology will be challenging.
