Cambridge Heavy Industries builds desktop fusion device, TechCrunch reports

According to TechCrunch, while fusion power is typically associated with massive industrial complexes outfitted with oversized magnets or lasers, a Cambridge, Massachusetts-based startup has been quietly developing a tabletop-ready device.

The Tech TL;DR:

• Cambridge Heavy Industries developed a modular benchtop fusion device operating out of a small lab near MIT.
• The startup secured a $6.2 million seed round led by Azolla Ventures to fund rapid experimentation.
• The system uses two main lasers to drive ignition, aiming to produce tritium before eventually scaling to power plant size.

Inside the Cambridge Benchtop Reactor Lab

During a video call with TechCrunch, Cambridge Heavy Industries co-founder and CEO Yun Kai chatted while the hardware’s optics were clearly visible right behind him. The company has been operating in stealth near MIT, giving an exclusive look at hardware designed to make experimentation faster and cheaper. We purposely built a small modular reactor. It’s tiny, it’s benchtop, Kai told TechCrunch. Because it’s small, it makes everything easier. That small scale allows the team to run between 50 and 80 experiments or shots per day. Data generated from those daily runs feeds simulations that use artificial intelligence to optimize subsequent designs.

That nimble iteration pace drew financial backing. Cambridge Heavy raised a $6.2 million seed round led by Azolla Ventures. Additional participation came from Overlay, Neta Foundation, P3A, MassCEC, and the Rothrock family.

Two Lasers Drive Fuel Target Compression

Cambridge Heavy’s fusion reactor uses lasers to compress a fuel target, sharing basic mechanics with the first experiment that proved controlled fusion reactions could produce more power than they consume. However, unlike other inertial confinement designs, this system minimizes the number of lasers required to spark fusion by relying on two main lasers to drive ignition.

One laser splits into multiple beam lines that deliver light in concentric rings. Those rings hit a flat, round fuel target successively, starting from the outside and working inward. The first ring starts a compression wave traveling toward the center. Subsequent rings boost the wave at precise moments to further compress the fuel. As the shock wave reaches the center, a final laser fires to generate heat and produce a magnetic field, resulting in fusion when pressure and heat thresholds are met. Kai noted that the design generates high pressures using relatively low laser power.

The core concept originated in the lab of Keith Nelson, a chemist at MIT. Researchers in that lab utilized laser pulses to study materials under extreme conditions. As they ramped up pressures, they observed conditions approaching fusion readiness.

Cambridge Heavy Plans Tritium Production and Power Plant

Over the next decade, Cambridge Heavy plans to scale the concept into a power plant. The resulting facility will be larger than the current benchtop prototype but smaller than other fusion power plants—roughly the size of two basketball courts—to test whether the approach generates sufficient energy.

Before that plant goes online, Cambridge Heavy intends to use its smaller devices to produce tritium, a rare hydrogen isotope required by nearly all fusion power plants currently in development. Tritium currently sells for around $30,000 per gram. While individual power plants require only grams per year, global supplies remain scarce, with only about 40 kilograms existing today. One recent study predicts that without new sources, the fusion power industry will face a deficit of about 28 kilograms by 2054, representing roughly $840 million at current prices.

While other fusion startups are designing fuel systems to achieve self-sufficiency, that engineering process could take up to a decade. Kai stated that this gap provides Cambridge Heavy with years of potential revenue from tritium production while it pursues its ultimate power plant goals.