South Korean nuclear fusion reactor breaks new record, brings ultimate clean energy closer
South Korea’s nuclear fusion reactor has sustained a reaction at temperatures in excess of 100 million degrees Celsius for 30 seconds. The time figure may not seem like much, nor does the temperature level represent a new milestone, but together they are a major achievement that demonstrates the viability of this new clean energy.
Seoul National University in South Korea publishes their achievement in the scientific journal Nature where they explain that Yong-Su Na’s team held the hot, ionized state of matter steady for half a minute. Controlling the plasma as hot as possible for a prolonged period is vital to turn nuclear fusion from a scientific experiment into a powerful source of energy.
The scientific community still considers that nuclear fusion is far from being a viable alternative to other energy sources, it is still many years away from being sufficiently stable, but its research and development continues to advance, as shown by announcements such as this one.
The problem of plasma stability
If it touches the walls of the doughnut-shaped reactor, the plasma cools rapidly, suffocating the reaction and causing considerable damage to the structure containing it inside the ring. To contain it, magnetic fields are used through various techniques.
In the case of the Seoul team, they have used the ITB technique, an internal transport barrier that creates a higher pressure near the center of the plasma, but can also cause instability like the other techniques. They have modified Korea’s superconducting tokamak KSTAR to make the plasma density lower, increasing temperatures in the center of the plasma while lowering those at the edge to protect the structure’s components and increase the reactor’s lifetime.
The reaction stopped after 30 seconds only because of hardware limitations, but longer periods should be achievable in the future. Still, the team acknowledges that it does not yet fully understand the mechanisms that facilitated this milestone.
Global technology challenge
The Korean reactor, KSTAR, is now shut down for upgrades, they are changing the carbon components of the reactor wall to components made of tungsten. They expect that this change will lead to improved productivity of the experiments.
In 2021, another experiment created a reaction energetic enough to be self-sustaining, meaning that the system produces more energy than is needed to keep it going, but the researchers responsible for the NIF in California have not been able to replicate that phenomenon since then.
Apart from studying the physics of nuclear fusion, most projects around the world are focusing on experimenting with the engineering to obtain the desired reaction and to be able to commercialize this energy, as the large European experimental fusion reactor ITER intends to do. Another of the great challenges they face is to obtain a safe method to extract the heat from the reactor and use it to generate electricity.