South Korean Scientists Get Nuclear Fusion Reactor Running at 100 Mln Degrees Celsius for 30 Seconds

The majority of scientists concur that practical fusion power is still decades away, while small but steady improvements in knowledge and outcomes continue to emerge. Conceptual designs for a commercial reactor are being built, and progress is being made on the massive ITER experimental fusion reactor in France.

A nuclear fusion reaction in South Korea has been observed lasting for 30 seconds at a scorching temperature of over 100 million degrees Celsius, newly published research in the journal Nature has claimed.

The simultaneous achievement of heat and stability takes the researchers closer to a functional fusion reactor, provided that the process can be scaled up, although the duration and temperature reached by the South Korean team's fusion reaction are not world records.

At the extraordinarily high temperatures needed for a functional reactor, Yong-Su Na and his team at Seoul National University in South Korea have run a reaction and kept the heated, ionized state of matter produced inside the apparatus stable for 30 seconds.

According to the team, it is crucial to regulate this so-called plasma. If it comes in contact with the reactor's walls, it rapidly cools, stifling the reaction and seriously harming the chamber that is holding it. The plasma is typically contained using a variety of magnetic field configurations.

Some researchers reportedly utilize an edge transport barrier (ETB), which molds plasma with a sharp pressure cutoff close to the reactor wall, preventing heat and plasma from escaping. Others employ an internal transport barrier (ITB), which raises pressure closer to the plasma's center. But either one can lead to instability.

At the the Korea Superconducting Tokamak Advanced Research (KSTAR) device, Na's team employed a modified ITB approach to achieve a significantly lower plasma density. Their strategy reportedly appears to raise plasma core temperatures while lowering plasma edge temperatures, which will likely increase the lifespan of reactor parts.

Low density, according to the research, was crucial, and "fast" or highly energetic ions near the plasma's core, known as fast-ion-regulated enhancement (FIRE), are essential to stability.

However, the team is still working to completely comprehend the underlying mechanics. Only due to hardware constraints was the reaction terminated after 30 seconds; greater periods should be feasible going forward.

KSTAR has now been shut down for improvements, and the scientists believe replacing the carbon in the reactor's wall with tungsten will increase experimental reproducibility.

"We have shown that abundant fast ions exist in the new regime and that they play an important role in confinement enhancement from the experimental observation and the simulation results," the research's conclusion read. "However, FIRE may not mean that fast ions fully determine all properties of confinement in the complex fusion plasma system. [...] Further improvement of FIRE modes to realize a longer steady-state operation for several hundred seconds with higher performance is foreseen as one of the promising paths towards a fusion reactor."

However, the success of the Korean scientists is not a world record in terms of both the temperature and the time. Last year, the Chinese Experimental Advanced Superconducting Tokamak (EAST), which replicates the atom-building process that takes place at the center of stars and gives them their luminosity and warmth, held plasma at a temperature of 120 million degrees Celsius for 101 seconds and at an even hotter temperature of 160 million degrees Celsius for another 20 seconds.

The EAST is located at the Hefei Institutes of Physical Science of the Chinese Academy of Sciences in China's Anhui Province.