Y Combinator and Mithril Capital Management are investing $1.5 million in Helion Energy, a Redmond, Washingon-based startup that says it has a plan to build a fusion reactor that breaks even on energy input and output, a challenge whose solution has been considered decades away for, well, decades. Unlike ITER, the international effort to build the world’s largest experimental fusion reactor, Helion isn’t aiming at designing a full-scale power station.
