Researchers have successfully tested a new £55-million nuclear fusion machine in the UK, which could provide vital insights for a future prototype power station.

The Mega Amp Spherical Tokamak (MAST) Upgrade at the Culham Centre for Fusion Energy in Oxfordshire took seven years to build. Today, the machine produced its first plasma, the state hydrogen reaches when heated to extremely high temperatures.

Our understanding of how stars are powered by hydrogen fusing into helium dates back around a century, but efforts to harness clean energy from the reaction in a commercial …