Helion's reactors are smaller and simpler field reversed configuration reactors. They've built multiple prototypes over the last 11 years: https://en.wikipedia

Helion's reactors are smaller and simpler field reversed configuration reactors. They've built multiple prototypes over the last 11 years: https://en.wikipedia.org/wiki/Helion_Energy#Development_history https://en.wikipedia.org/wiki/Helion_Energy#Development_hist... The prototype currently under construction is Polaris. It's 25% larger than the previous prototype and they expect it to achieve net electricity production: https://www.helionenergy.com/polaris/ https://www.helionenergy.com/polaris/