1.1 kiloelectronvolts, or about 12.6 million degrees Celsius. That is the electron temperature General Fusion says its LM26 machine reached just before peak compression, in results announced on Thursday with the UK Atomic Energy Authority.
The Canadian company’s approach is unusual. It uses neither superconducting magnets nor high-powered lasers. It squeezes the plasma mechanically with a metal liner, over milliseconds, where other compression schemes work in microseconds or less. It says LM26 is the first machine to pass 1 keV with compression that slow.
The UKAEA’s involvement lends the claim weight. The authority co-authored the technical paper and helped design and commission the Thomson scattering system that took the reading, building a key component at its Culham campus.
Dennis Whyte, the UKAEA’s chief executive, called it an important milestone and said hot electrons are a necessary step in proving a fusion confinement concept.
A necessary step is a careful phrase. Passing 1 keV is a marker a handful of fusion companies have reached, all by other routes. It is far from the conditions for net energy, which need temperature, density and confinement time together.
The company’s next target is 10 keV, and it has given no date. Upgrades to raise the compression ratio are under way. General Fusion still aims to start operating a first plant around 2035.
Two asterisks. The paper has been submitted for peer review, not passed it. And the headline figure is for electrons, while fusion happens between ions. The company’s own release puts the ion temperature at about 0.46 keV, less than half.
