Nuclear Fusion Record Smashed
But does this bring us closer to unlocking this utopian energy source?
A few days ago, South Korea’s Korea Superconducting Tokamak Advanced Research (KSTAR) obliterated its own fusion record by sustaining a temperature of 100 million degrees Celsius for an astonishing 48 seconds! For some sense of scale here, that is 17,857 times hotter than the surface of the Sun and nearly 7 times hotter than the core of the Sun! KSTAR’s previous 2021 record was for the same temperature, but only for 31 seconds, so this marks a significant leap forward. But the question has to be asked: does this bring us any closer to unlocking the ultimate clean energy source, nuclear fusion? Well, yes, it does; let me explain.
Let’s start with what fusion is and why it could be so revolutionary.
Nuclear fusion is the process that powers the Sun. In its core, the temperatures are so high and the pressure is so intense that hydrogen atoms have enough kinetic energy to overcome the repulsive force that keeps them separate and fuse into a single larger helium atom when they collide. Helium weighs slightly less than two atoms of hydrogen, so there is a bit of spare mass floating around in the form of subatomic particles. These particles can’t physically exist without being attached to protons or neutrons, so they turn into energy and radiate out. Now, if you paid attention in physics class, you’d remember that Einstein’s famous equation E=MC² means that a tiny bit of matter is equal to an utterly vast amount of energy!
As such, a single kg of hydrogen can produce 177,717 MWh of energy through fusion, or 7.9 times more than a kg of pure uranium-235 produces through fission or 14.8 million times more energy than a kg of gasoline through combustion! But, unlike uranium or gasoline, fusion doesn’t produce any radioactive waste or climate-destroying emissions. The only by-product is valuable non-radioactive helium gas.
So, if we can replicate the Sun and harness this process ourselves, we could power the entire world with copious amounts of on-tap carbon-neutral energy from only a few hundred tonnes of hydrogen each year.
But here is the problem: the fusion reactors we have created so far have all used more energy to generate fusion than they produce from fusion, rendering them useless as power sources.
Now, KSTAR is a tokamak fusion reactor. This design uses a reaction chamber shaped like a doughnut and about the same size as a large car, surrounded by superconducting electromagnets. Hydrogen plasma is pumped into the chamber, and because it reacts to magnetic fields, the magnets heat it up through induction (the same way an induction cooker heats up pans) and squeeze it. These magnets can’t recreate the same pressure at the core of the Sun, so to reach the level of kinetic energy necessary for fusion to occur, the plasma needs to be significantly hotter than the core of the Sun.
As you can imagine, handling plasma this hot in such a confined space is insanely difficult. Not only can this plasma severely damage the walls of the reactor if things go wrong, but a poorly managed plasma can have huge losses through instability and turbulence, which can rapidly cool the plasma, making achieving a net gain in energy impossible.
So, how has KSTAR managed to achieve such a record-setting length of fusion? Well, they have honed their plasma management methods over the years and recently updated the reactor, replacing the carbon “divertors” with tungsten ones. These extract heat and unwanted by-products from the reaction chamber, and the tungsten is more efficient at doing this than the carbon, enabling them to keep the walls of the reactors cooler and run the reactions for longer without sustaining damage.
Okay, so why does that matter?
Well, KSTAR itself will never produce a net gain in energy. It is too small and not powerful enough to create “burning plasma,” where the energy of one fusion reaction is retained by the plasma, creating more fusion reactions in a chain reaction. This burning plasma is the secret sauce to make these machines produce way more energy per unit of energy put into them. However, KSTAR is a test platform for ITER. ITER is currently under construction in France and will be the world’s biggest and most powerful tokamak by a vast margin. This size and power should enable ITER to produce ten times more energy from fusion than it takes to run it, making ITER a viable energy source! However, it can only reach those numbers if it can run its reaction pulses for long enough. So, this breakthrough at KSTAR could mean that ITER can be the world’s first feasible fusion power plant.
Now, KSTAR scientists aren’t finished and aim to push the reactor to sustain temperatures of 100 million Celsius for 300 seconds by 2026. What’s more, ITER won’t start proper fusion operations until 2035. So, we will likely see yet another huge leap forward from KSTAR in the near future, but we won’t know what implications these leaps forward will have for the world of fusion energy for at least a decade.
Thanks for reading! Content like this doesn’t happen without your support. So, if you want to see more like this, don’t forget to Subscribe and follow me on BlueSky or X and help get the word out by hitting the share button below.
Sources: Space.com, Euronews, Science Alert, World Nuclear News, Will Lockett, ITER