Helion said its Polaris prototype reached 150 million°C plasma temperatures and began operating with deuterium-tritium fuel, which it claims makes it the first fusion company to run D-T in a prototype while boosting fusion heat output.

If the D-T operation is sustained, it reduces technical uncertainty around whether Polaris can reach the higher temperature and power-density regime Helion says it needs for a commercial plant. The milestone tightens the execution path toward Helion’s stated 2028 delivery timeline by moving the program from temperature targets to repeatable D-T runs and heat-output scaling. Competitors and potential offtakers can treat this as a nearer-term signal to reassess procurement timelines, grid interconnection planning, and partnership options tied to fusion pilot deployments.