Just last week, we reported that Germany’s revolutionary nuclear fusion machine managed to heat hydrogen gas to 80 million degrees Celsius, and sustain a cloud of hydrogen plasma for a quarter of a second.
This was a huge milestone in the decades-long pursuit of controlled nuclear fusion, because if we can produce and hold onto hydrogen plasma for a certain period, we can harness the clean, practically limitless energy that fuels our Sun.
Now physicists in China have announced that their own nuclear fusion machine, called the Experimental Advanced Superconducting Tokamak, has produced hydrogen plasma at 49.999 million degrees Celsius, and held onto it for an impressive 102 seconds.
Sustaining these incredibly high temperatures for long enough to harness the energy produced by the reaction is key to achieving controlled nuclear fusion, as it allows for more stable alignment of the magnetic fields that are used to manoeuvre the plasma away from the walls of the machine, and the collection of high-energy particles and heat energy that are produced as part of the reaction.
Nuclear fission, which is what our current nuclear facilities achieve, generates energy by splitting the nucleus of an atom into smaller neutrons and nuclei.
While nuclear fission requires things to be heated to just a few hundred degrees Celsius, nuclear fusion machines have to recreate conditions on the Sun, which means we’re talking several million degrees.
Because our machines are essentially starting their reactions from scratch, we actually need to achieve temperatures far hotter than those estimated to exist in the centre of the Sun – the team behind Germany’s US$1 billion stellarator nuclear fusion machine says the ideal temperature is 100 million degrees Celsius.