While harnessing the power of the Sun has progressed in leaps and bounds in recent years, harnessing the process that powers the Sun is proving a tough nut to crack. However, progress continues to be made on the various approaches to practical nuclear fusion being pursued, of which tokamak reactors remain a frontrunner. In another promising development for the technology, the Korea Superconducting Tokamak Advanced Research (KSTAR) fusion device has set a world record by maintaining plasma at over 100 million °C (180 million °F) for 20 seconds.
Completed in 2007 and achieving first plasma in 2008, in 2016 KSTAR set a world record for the longest operation in high-confinement mode by successfully maintaining a high-temperature hydrogen plasma at about 50 million °C (90 million °F) for 70 seconds. China subsequently claimed a new record in 2017 with its Experimental Advanced Superconducting Tokamak (EAST), managing to maintain plasma at a similar temperature for 102 seconds.
But although 50 million °C might sound plenty toasty, when you’re talking about the process that powers the Sun you need to get to at least double that to give the ions the kinetic energy to overcome the repulsive electrostatic force, known as the Coulomb barrier, that stops them from fusing together. You also need to successfully confine the ions close enough to each other for long enough to avoid plasma cooling, and ensure the ions are confined at a high enough density to maintain a suitable reaction rate.