For the first time, the Korea Institute of Fusion Energy's KSTAR fusion reactor has reached temperatures seven times higher than those of the Sun's core. The result was achieved during testing between December 2023 and February 2024. The resulting temperature is a new record for the fusion reactor project.
Scientists in the project were able to maintain temperatures of 100 million degrees Celsius for 48 seconds. For comparison, the temperature of the Sun's core is 15 million degrees Celsius.
In addition, the reactor was able to maintain high containment mode (H-mode) for over 100 seconds. In the H-mode, a steady state of the plasma is characteristic.
This is the latest of many successes for KSTAR. In 2021, the reactor operates at one million degrees and maintains super-hot plasma for 30 seconds.
How does KSTAR work?
Nuclear fusion is a process that mimics the same process that generates light and heat from stars. This involves fusing hydrogen and other light elements to release enormous amounts of power, which experts in the field hope to harness for limitless, zero-carbon electricity.
According to Korea's National Research Council for Science and Technology (NST), creating technology that can sustain high-temperature and high-density plasma, where fusion reactions run most efficiently for extended periods, is critical to the energy transition.
The secret of success – the use of tungsten
According to NST, the secret behind these great achievements is tungsten deflectors. These are key components located at the bottom of a vacuum vessel in a magnetic fusion device. They play a critical role in expelling waste gases and impurities from the reactor while withstanding significant surface heat loads.
The KSTAR team recently switched to using tungsten instead of carbon. Tungsten has the highest melting point of all metals, and the team's success in maintaining H-mode for longer periods of time is largely due to this successful upgrade.
Compared to previous carbon-based deflectors, the new tungsten deflectors showed only a 25% increase in surface temperature under similar heat loads. This provides significant advantages for high-power, long-pulse heating operations," NST explained.
International project
The success of the tungsten deflectors could provide invaluable data for the International Thermonuclear Experimental Reactor (ITER) project.
ITER is a $21,5 billion international fusion megaproject being developed in France by dozens of countries, including Korea, China, the US, the EU and Russia.
According to Recharge News ITER is expected to achieve its first plasma in 2025 and be fully operational by 2035.