One of the possible pathways to limitless and clean energy can be found in hollow, doughnut-shaped chambers known as tokamak nuclear fusion reactors. A relatively new player on the scene, a UK company called Tokamak Energy, is claiming a new milestone in the area after heating its ST40 device to 15 million degrees Celsius, similar to temperatures found at the center of the Sun.

The pursuit of nuclear fusion is inspired by the collision of atomic nuclei in stars, which fuse together to form helium atoms and release huge amounts of energy in the process. If we can recreate this process we could have an inexhaustible supply of energy on our hands that brings no harmful by-products, such as carbon dioxide emissions or the radioactive waste generated at nuclear fission-based power plants like Fukushima and Chernobyl.

But to do that we need to create Sun-like conditions here on Earth, which calls to mind one requirement first and foremost – incredible amounts of heat. Tokamak Energy hopes to achieve this through what's known as merging compression, where running high currents through two symmetrical magnet coils generates two rings of plasma, or electrically charged gas, around them.

Reducing the coil current to zero then sees these plasma rings drawn to one another and combine into one. This merger is what creates huge amounts of energy and heats the plasma, with sets of magnets designed to stabilize the ring of plasma streaming around the spherical chamber in order maximize the opportunity for fusion reactions.

Tokamak Energy has now fired up its tokamak reactor and achieved plasma temperatures of over 15 million° C (27 million° F), but according to the team, it is just warming up. The goal is to eventually hit temperatures of 100 million° C (180 million° F), which it says is necessary to force deuterium and tritium particles together, on its way to making commercial fusion power a reality by 2030.

"The world needs abundant, controllable, clean energy," says co-founder Dr David Kingham. "Our business plan is built on strong scientific foundations and this milestone is a significant step in our compact spherical tokamak route to fusion power."

Other notable tokamak projects in the works include China's EAST tokamak, which was reported to heat plasma to three times the temperature of the Sun's core and sustain it for 102 seconds, and the International Thermonuclear Experimental Reactor (ITER), which will be the largest tokamak fusion reactor in the world. A collaboration between 35 countries, ITER is expected to enter operation in 2027.

You can hear Tokamak Energy's CEO Jonathan Carling talk about the company's milestone in the video below.

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