Thea Energy Raises $100M Series B to Advance Stellarator Fusion
May 27, 2026
Thea Energy, a U.S. startup pursuing commercial fusion power, has raised a $100 million Series B. Investors in the round include Japan’s Idemitsu Kosan.
Fusion energy uses the same kind of reaction that powers the sun. If it works at scale, it could deliver large, steady amounts of electricity with almost no carbon emissions.
At the same time, to use fusion for power generation, the fuel must be confined stably at temperatures above 100 million degrees Celsius. This superheated fuel is called plasma, and ordinary containers cannot hold it. That is where powerful magnets become essential.
Thea Energy is pursuing commercial fusion with its own approach: using software to finely control these magnets.
Inside Thea Energy’s $100 Million Series B
According to Thea Energy, the Series B was oversubscribed and totaled $100 million. The round was led by the U.S. Innovative Technology Fund (USIT), the investment firm run by Thomas Tull.
Investors included Japan’s Idemitsu Kosan, along with returning backers such as Hitachi Ventures and Lowercarbon Capital. The company closed a $20 million Series A in early 2024, bringing total private investment to $130 million.
The money will support a second facility in Northern New Jersey to expand magnet manufacturing capacity, the construction of a demonstration device called Eos, and a doubling of the workforce.
Controlling Magnets Like Pixels
Thea Energy’s distinguishing feature is how it uses magnets.
In fusion, superheated plasma is held in place by the force of magnets. Because the plasma is too hot, it cannot touch a metal container directly. Instead, magnetic fields must hold it suspended.
Thea Energy lines up many small magnets and finely controls each one through software. The company compares this setup to the pixels of a screen.
Smartphone and television screens are made up of many small pixels that together form a single image. In a similar way, Thea Energy is trying to build the complex magnetic field needed to contain plasma by controlling many small magnets in fine detail.
Why This Technology Matters
Thea Energy uses a fusion-reactor design known as a stellarator.
Stellarators are considered relatively good at holding plasma stably. On the other hand, confining plasma well requires a very complex magnetic-field shape, so historically that has meant complex magnets and complex reactor structures, making them hard to build.
Thea Energy is trying to solve that problem with software-controlled magnets. Rather than starting with complex-shaped magnets, the company combines comparatively easier-to-make magnets and adjusts them finely with software to produce the needed magnetic field.
The idea is to shift some of the complexity away from hardware shape and into software control. That is why Thea Energy describes its approach as “pixel-like.”
Whether this approach really works in a large fusion reactor still needs to be proven. Promising results at lab scale do not automatically translate to large-scale equipment, and whether the same manufacturability and stability hold at full size will be the focus going forward.
When Could Commercial Fusion Arrive?
Thea Energy is targeting 2030 for its Eos demonstration device and 2034 for a commercial reactor called Helios.
That timeline is close to that of rival Commonwealth Fusion Systems, which is working on an Arc demonstration reactor in Virginia. Among fusion startups, whether they can deliver demonstration-level results in the early 2030s is becoming a major focal point.
That said, fusion is a field that needs huge capital and long timelines to reach commercialization. This round of funding is a meaningful step forward, but a working power plant is not just around the corner.
Going forward, the points to watch are whether Eos construction targeting 2030 proceeds on schedule and whether Thea Energy’s magnet technology will hold up in a large fusion reactor.
Sources
Bloomberg – Thea Energy Raises $100 Million to Build Fusion Power Prototype
TechCrunch – With a new $100M raise, Princeton’s Thea Energy is now a top-funded fusion startup
