Helion Raises $425M for Microsoft Fusion Reactor

Fusion energy has long been a tantalizing dream for the energy sector, promising clean, nearly limitless power. Among the ambitious startups chasing this goal, Helion Energy stands out. The 12-year-old company recently raised $425 million in a Series F round, bringing its valuation to $5.245 billion. Backed by high-profile investors, including Sam Altman, Helion plans to deliver fusion-generated electricity to Microsoft by 2028—years ahead of competitors.

Breaking Ground with Polaris: A Unique Fusion Approach

Helion has been developing Polaris, its seventh prototype, at its Everett, Washington, facility. Unlike most fusion designs, Helion employs a field-reversed configuration reactor. This method uses powerful magnets to compress plasma during a "pulse," creating fusion reactions. What sets Helion apart is its ability to directly convert the resulting magnetic energy into electricity—bypassing traditional turbine-based methods.

The current design can pulse a few times per second, and each reactor is expected to generate 50 megawatts of electricity. Future versions might pulse at grid-level frequencies of 60 pulses per second, though this presents engineering challenges.

Tackling Supply Chain and Manufacturing Hurdles

CEO David Kirtley acknowledged that supply chain issues—such as sourcing capacitors and magnetic coils—have been a bottleneck. The new funding will enable Helion to expand in-house manufacturing capabilities, aiming to shorten production timelines significantly.

“Our goal is to go from waiting three years for a supplier to deliver capacitors to making them ourselves in under a year,” Kirtley said.

The Road to 2028: A Commercial Power Plant

Helion is simultaneously working on site selection, permitting, and grid interconnection for its first commercial-scale power plant. Despite these long lead times, Kirtley remains optimistic about meeting Microsoft’s ambitious deadline.

Investors Backing the Vision

The Series F round was backed by prominent names, including Lightspeed Venture Partners, SoftBank Vision Fund 2, and a major university endowment. Existing investors—such as Sam Altman, Capricorn Investment Group, and Dustin Moskovitz—also participated. While smaller than its previous $500 million round, this funding ensures Helion can push forward on its prototype and commercial goals.

A Bold Bet on Fusion’s Future

Helion’s unorthodox approach has both supporters and skeptics, but its efficiency-focused design and rapid progress position it as a leader in the fusion race. If successful, Helion’s fusion reactor could revolutionize energy production by offering a cleaner, more efficient alternative to traditional power sources.

With its innovative technology and growing investor support, Helion is poised to prove that fusion energy is no longer a distant dream—it’s a potential reality by 2028.