South Korea’s Artificial Sun Is Cooking 100 Million Degree Plasma

The Korea Institute of Fusion Energy has implemented a new diverter in their KSTAR tokamak, often dubbed an 'artificial sun' due to its replication of the sun's nuclear fusion. This innovation will enable it to maintain high ion temperatures of over 100 million degrees Celsius for extended periods. KSTAR was finished in 2007, and achieved its first plasma in 2008. It is roughly one-third the size of a similar reactor being constructed in France. Both reactors utilize tokamaks, doughnut-shaped devices used for nuclear fusion involving plasmas or highly pressurized, super-heated gases.

KSTAR's diverter, situated at the bottom of the tokamak, manages waste gas exhaust and purges impurities from the reactor. Acting as a plasma-facing element inside the tokamak, the diverter must withstand the intense internal heat. At present, KSTAR can achieve plasma operations for approximately 30 seconds. However, the goal is for the new diverter to extend these operations to 300-second intervals by the close of 2026.

Previously, KSTAR utilized a carbon diverter, but in 2018, research on a tungsten diverter began due to its higher melting point and ability to enhance the reactor's heat flux limit twofold, as stated by Korea's National Research Council of Science and Technology. The diverter's prototype was finalized in 2021, with the installation wrapping up last year. Suk Jae Yoo, the president of KFE, shared that the tungsten diverter was chosen to mirror the ITER's choice, and they plan to contribute significantly to collecting necessary data for the ITER through KSTAR experiments.

Nuclear fusion research has seen slow but steady progress, particularly in 2022 when scientists at Lawrence Livermore National Laboratory had a first-time breakthrough. The aim is a reliable, zero carbon energy source, a goal which is still a way off, but the field is making steady advances. The first plasma for ITER is slated for 2025, with the first fusion projected for 2035. However, delays and cost-overruns, from €5 billion in 2006 to over €20 billion now, might result in a longer wait time.

These are nonetheless exciting times for tokamak reactors. Recently, Japan's six-story JT-60SA reactor was inaugurated, and it is estimates that the development of plasmas for experiments will take approximately two years. With over 50 tokamaks around the world in operation, KSTAR will continue plasma experiments with their new tungsten diverter through February, according to Korea's National Research Council of Science and Technology. The goal is to ensure a stable environment for experimentation and reproduce the 100 million degree plasma within it.