KSTAR Fusion Reactor Installs Tungsten Divertor for Improved Performance

Sunday - December 31 2023, 13:13 UTC - 10 months ago

KSTAR, the Korea Institute of Fusion Energy's (KFE) artificial Sun, has modifed its reactor by installing a tungsten divertor, promising extended periods and increased temperatures. This divertor is a sophisticated system comprised of 64 cassettes which helps the reactor handle waste gases and endure the most substantial surface heat loads. Ongoing plasma experiments are set to commence in 2024.

KSTAR, the Korea Institute of Fusion Energy's (KFE) artificial Sun, has completed a significant modification that would allow it to function for longer periods at higher temperatures. KSTAR stands for Korea Superconducting Tokamak Advanced Research, an advanced nuclear fusion reactor constructed in 2007.

The development in this regard involved the installation of its newly developed tungsten divertors, "allowing it to operate for extended periods sustaining high-temperature plasma over the 100 million degrees," according to a statement by the institute.

The team claimed they could complete a plasma experiment with the reactor equipped with the new divertor on December 21. In 2021, KSTAR set a new record by running at one million degrees and maintaining super-hot plasma for 30 seconds.

Significant upgrade .

Nuclear fusion, like what happens in the Sun, creates abundant energy. Scientists use tokamaks, special reactors on Earth with strong magnets, to control super-hot plasma. This plasma, as hot as millions of degrees, makes atoms collide and create heavier nuclei, releasing much sustainable energy. This could help us use less fossil fuel and fight climate change.

The divertor is a vital component located at the bottom of the vacuum vessel in a magnetic fusion device. It plays a crucial role in handling the expulsion of waste gases and impurities from the reactor while simultaneously enduring the most substantial surface heat loads. According to the team, developing and deploying a highly heat-resistant divertor is essential due to its pivotal function.

Originally, KSTAR utilized a carbon divertor. However, the increased performance and extended operational duration at temperatures of 100 million ℃ surpassed the heat flux limit of the carbon divertor.

Exceeding heat flux on the carbon divertor necessitated the team to develop a divertor employing tungsten. The culmination of this effort resulted in the completion of the first tungsten divertor prototype in 2021. Subsequently, the reactor had a long and thorough installation process that lasted over a year, commencing in September 2022.

The newly installed divertor is a sophisticated system comprising 64 cassettes carefully crafted from tungsten mono-blocks. These cassettes collectively envelop the entirety of the bottom section of the vacuum vessel, forming a solid barrier to manage and withstand the heat loads encountered in the fusion environment. This innovative design addresses the thermal challenges encountered with the previous carbon divertor. According to the team, it reflects a significant stride in enhancing the performance and longevity of KSTAR's operations at extreme temperatures.

High melting point .

Due to its exceptional properties, including a high melting point and minimal sputtering characteristics, tungsten has emerged as the most suitable material for the divertor. Researchers claim that the material choice has yielded substantial improvements, with the heat flux limit now exceeding twice that of the carbon divertor, reaching an impressive 10 MW/m².

Ongoing plasma experiments within the newly implemented tungsten divertor ring are set to commence in 2024.