Billion-dollar New Mexico facility aims to be first to get more energy out of fusion than it uses

A US start-up has begun assembling a billion-dollar fusion machine that it hopes will become the first to generate more energy than it consumes, using immense pulses of electricity rather than lasers to squeeze hydrogen fuel until its nuclei fuse (Nature). Pacific Fusion's demonstration facility in Los Lunas, New Mexico — sited down the road from a major nuclear-weapons laboratory — could also be used to study the country's ageing warhead stockpile, the company says.

Nature visited the site earlier this month, where workers and industrial robots were piecing together the first two of more than 150 truck-sized impedance-matched Marx generators: cylindrical capacitor banks that will ring a central reaction chamber like the legs of a giant metal crab. Fired in parallel, they are intended to deliver an electrical pulse thousands of times more powerful than a lightning bolt onto a pea-sized fuel capsule, generating a magnetic field that compresses the fuel until the hydrogen isotopes fuse into helium and release energy.

Pacific Fusion aims to reach 'net facility gain' — more energy out of the whole machine than goes in — by the end of the decade, an important benchmark on the way to a practical fusion power plant. The company has raised more than $1 billion since its founding in 2023, contingent on hitting technological milestones, part of a surge that has seen fusion start-ups collectively attract over $14 billion in investment in five years, spurred by the National Ignition Facility's landmark 'ignition' shot in 2022. The NIF achieved more energy from fusion than hit the target, but never net facility gain, because far more power was needed to fire its 192 lasers.

Pulsed power offers a more direct route from electrical charge to fuel compression than lasers: at the NIF less than 1% of the initial charge reaches the capsule, whereas around 12% should reach the target in Pacific Fusion's design, chief technology officer Keith LeChien said. He expects each shot to use about 80 megajoules of electricity and yield about 100 megajoules of fusion energy — but even then, the gain would be roughly one-fifth of what a commercial plant would require.

Fusion researchers contacted by Nature called the technique promising but flagged the distance still to travel. "There's still a long ways to go," said Michael Campbell, a fusion engineer at the University of California, San Diego. Kyle Peterson, a plasma physicist at Sandia National Laboratories, which is working cooperatively with Pacific Fusion on both energy and weapons applications, said the proliferation of approaches reflects genuine uncertainty: "One of the reasons you see so many companies with different approaches is that the answer isn't obvious."

**Sources:** Nature