nuclear fusion

Scientists have been trying to harness the power of nuclear fusion (the process that makes stars burn) for more than 70 years. They produce light and heat by combining hydrogen atoms with helium at extremely high pressures and temperatures, producing vast amounts of energy without producing greenhouse gases or radioactive waste.

But recreating the conditions in the hearts of stars is no easy task. The most common fusion reactor design, the tokamak, works by superheating plasma (one of four states of matter composed of positive ions and negatively charged free electrons) and trapping it inside a donut-shaped reactor chamber with strong magnetic fields.

However, keeping coils of turbulent and superheated plasma in place long enough for nuclear fusion to occur was a laborious process. No one has yet succeeded in creating a reactor that can consistently deliver more energy than is required to start and maintain it..

One of the main hurdles was how to deal with plasma hot enough for fusion. Fusion reactors require very high temperatures (many times higher than the Sun) because they must operate at much lower pressures than where fusion occurs naturally in the cores of stars. For example, the core of the Sun reaches temperatures of about 15 million degrees Celsius, but has a pressure of about 340 billion times the air pressure at sea level on Earth.

It is relatively easy to heat the plasma to these temperatures, but it is technically difficult to find a way to keep it in a way that does not burn the reactor and destroy the fusion process. This is usually done using lasers or magnetic fields.

To increase the plasma burn time compared to the previous record launch, scientists changed some aspects of the reactor design, including replacing carbon with tungsten to increase the efficiency of the tokamak’s “directors” that remove heat and ash from the reactor.

Although this was the first experiment conducted in the presence of the new tungsten deflectors, careful equipment testing and campaign preparation enabled us to quickly achieve results that surpassed previous KSTAR records.
– said KSTAR Research Center Director Si-Woo Yoon.

This record joins others set by rival fusion reactors around the world, including the US government-funded National Ignition Facility (NIF), which made headlines after the reactor’s core briefly released more energy than it could contain.