Helion achieved a plasma temperature of 150 million degrees Celsius in its Polaris prototype. This temperature represents a record for a private fusion company.
The milestone brings Helion closer to the 200 million degrees required for its commercial system. Helion also became the first private venture to conduct tests using deuterium-tritium fuel.
The company aims to deploy the world's first commercial fusion power plant by 2028. Helion will supply electricity to Microsoft under a landmark power purchase agreement.
OpenAI CEO Sam Altman chairs the startup. Helion is developing a pulsed, non-ignition fusion system designed to recover electricity directly for improved scalability.