South Korean ‘artificial sun’ reaches 7 times the Sun’s core temperature

Furthermore, it maintained the high confinement mode (H-mode) for over 100 seconds. H-mode is a stable plasma state that is better confined than low confinement mode.

This is the latest in many successes for KSTAR, too. For example, in 2021, KSTAR set a new record by running at one million degrees and maintaining super-hot plasma for 30 seconds. 

KSTAR: 7 times hotter than Sun

Fusion is a process that mimics the same process that generates light and heat from stars. It involves fusing hydrogen and other light elements to release tremendous power that experts in the field hope to harness for unlimited, zero-carbon electricity. This is often called the ‘Holy Grail’ of the energy transition.

According to Korea’s National Research Council of Science & Technology (NST), creating technology that can maintain high-temperature and high-density plasmas where the fusion reactions occur most effectively for extended periods is crucial.

According to NST, the secret behind these major achievements is tungsten divertors. These are vital components located at the bottom of the vacuum vessel in a magnetic fusion device.

They play a crucial role in expulsing waste gases and impurities from the reactor while enduring substantial surface heat loads. The KSTAR team recently switched to using tungsten instead of carbon in its diverters.

Tungsten has the highest melting point of all metals, and the team’s success in maintaining H-mode for longer periods of time is mainly attributed to this successful upgrade. The NST reports that this change has been a significant improvement.

Tungsten is the secret sauce

“In comparison with the previous divertors based on carbon, the new tungsten divertors showed only 25% increase in surface temperature under similar heat loads. This provides significant advantages for long-pulse high-heating power operations,” the NST explained.

The success of tungsten diverters can provide invaluable data for the International Thermonuclear Experimental Reactor (ITER) project. ITER is a $21.5bn international fusion megaproject being developed in France by dozens of countries, including Korea, China, the US, the EU, and Russia.

Recharge News reports that ITER is expected to achieve its first plasma in 2025 and be fully commissioned by 2035. Tungsten will be used in its own divertors.

Suk Jae Yoo, the President of the Korea Institute of Fusion Energy, has announced that the research is a “green light” for getting the core technologies needed for “DEMO reactors,” which are demonstration power plants in the future.

His team will now aim to secure core technologies necessary for the operation of ITER and future DEMO reactors.