Artificial Sun Hits 180 million Degrees Fahrenheit in Race for Near-Limitless Clean Energy

A commercial "artificial sun," or tokamak, has achieved a world-first for a private company, generating plasma at 180 million degrees Fahrenheit (100 million degrees celsius), the temperature at which fusion can take place.

Tokamak Energy, based near Oxford in the United Kingdom, announced that its privately funded ST40 spherical tokamak had achieved the important temperature milestone on Thursday, calling it "the threshold required for commercial fusion energy."

While several government-funded fusion experiments such as Korea Superconducting Tokamak Advanced Research (KSTAR), have hit this temperature milestone, this is the first time a private fusion company has done the same, and with a much more compact machine.

Tokamak Energy CEO Chris Kelsall said in a statement: "We are proud to have achieved this breakthrough which puts us one step closer to providing the world with a new, secure, and carbon-free energy source."

The process is almost the opposite of nuclear fission, which powers current nuclear plants and takes heavy elements and splits them into smaller atoms. The problem is the precursors to the these reactions like uranium, are expensive, and the by-products are radioactive and thus difficult to dispose of.

Fusion however uses heavy hydrogen or deuterium as a precursor to reactions, something that can be extracted from seawater. The by-product of the fission reaction is helium, making it a clean process too.

Why Do Tokamaks Have to Be Hotter Than the Sun?

At the heart of stars, the immense gravitational pressure of these massive stellar bodies overcomes the repulsion between hydron ions—atoms that have been stripped of electrons leaving them with a positive charge—forcing them together. This results in the fusion of hydrogen atoms to create helium with the difference in mass released as energy.

The immense gravitational forces generated by stars can't be replicated on Earth, which means much higher temperatures are required to drive together hydrogen in the plasma generated in tokamaks.

The center of the Sun, where hydrogen fusion takes place, has an estimated temperature of around 27 million degrees Fahrenheit, meaning that the optimal temperature for fusion to take place in tokamaks is about seven times greater than those at the heart of the Sun.

Tokamaks need more than superheated temperatures, however, they also depend of powerful magnets to constrain and contain this plasma. Tokamak Energy says that their machine, the ST40 spherical tokamak, will now be upgraded to include high-temperature superconducting (HTS) magnets.

Kelsall continued: "When combined with HTS magnets, spherical tokamaks represent the optimal route to achieving clean and low-cost commercial fusion energy."

The device will serve as a template for the development of future fusion technology and advancements that Tokamak Energy said will form the basis of the design of a world-first fusion pilot plant, set to be commissioned in the early 2030s.

"Our next device will combine these two world-leading technologies for the first time and is central to our mission to deliver low-cost energy with compact fusion modules."

The sun
The Sun as imaged by NASA's Solar Dynamics Observatory. Replicating the fusion processes here on Earth means generating plasma with temperatures in excess of 180 million degrees Fahrenheit. Solar Dynamics Observatory/NASA