Inertia raises $450M to turn NIF’s fusion breakthrough into grid power

Inertia’s founding team unites NIF ignition expertise with commercial engineering resolve.

(Image courtesy of Inertia)

Inertia Enterprises has closed a $450 million Series A to commercialise the physics first demonstrated at the National Ignition Facility, bringing together the scientist who designed the experiments that achieved fusion ignition and the engineer who spent five years validating what a commercial plant based on that result might actually look like.

The Livermore, California startup was founded in August 2025 by Twilio founder Jeff Lawson, NIF lead target designer Dr Annie Kritcher, and Stanford professor and SLAC associate lab director Prof Mike Dunne. Bessemer Venture Partners led the round, with GV, Modern Capital, Threshold Ventures and others participating. The funding is milestone-based, structured around Inertia’s two core development tracks: building Thunderwall, its grid-scale laser system, and standing up a production line capable of mass-manufacturing fusion fuel targets.

Thunderwall is the technical centrepiece. The system is designed to deliver 10kJ pulses at a repetition rate of ten times per second, with 10% wall-plug efficiency driven by scalable semiconductor diode technology. Inertia says that puts its average power output at roughly 50 times that of any comparable laser built to date. The fuel targets themselves draw directly from Kritcher’s NIF capsule design, adapted for high-volume fabrication at low cost, though the company has not publicly confirmed a per-unit cost figure. The goal is to feed targets into reaction chambers fast enough to sustain steady gigawatt-scale output.

The underlying approach is inertial confinement fusion using indirect drive, the same method NIF uses to focus laser energy through a hohlraum, a small gold cylinder that converts the beams into X-rays that then compress and ignite a deuterium-tritium fuel capsule. NIF first achieved scientific energy gain in December 2022 and has since repeated and improved on the result. That track record is what Inertia is betting on. Rather than pursuing magnetic confinement routes or alternative fuel cycles, the company is making a straightforward case that the hard physics problem is already solved and the engineering challenge, while substantial, is at least bounded.

Dunne is well placed to make that argument. Before joining Inertia, he led a five-year LLNL programme to produce an industry-validated fusion power plant design, working with more than seventy vendors, utilities, national labs and universities. That body of work underpins Inertia’s commercialisation roadmap, which targets pilot plant construction starting in 2030 and a full gigawatt-scale utility plant within the decade. Risks around laser component durability and target supply chain reliability remain real, but investors are clearly betting that this team, more than any other, has the institutional knowledge to retire them.

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