Longview Fusion and Focused Energy

Inertial confinement fusion (ICF) using lasers would resemble the rapid-fire explosions of an internal combustion engine. The NIF’s (National Ignition Facility) shot had a one-off ignition event. An ICF-based power plant may need to fire up to 10 laser shots per second, consuming almost 1 million targets a day, and produce far more energy per shot than NIF did.

Longview Fusion

Ed Moses, a former NIF director, has founded a company, Longview Fusion, that hopes to start building a test plant in 5 years with twice as many laser beams (400) as NIF (192). It would shoot 10 targets per second—sheathed in lead instead of gold to lower costs—into a reaction chamber and blast them to produce a string of quick-fire fusion explosions. “It’s not hard,” Moses says. “The technology is all available, it just has to be integrated.”

In December 2022, NIF produced a record-breaking 3.15 megajoules of energy from a 2.05 megajoule laser pulse, a gain of about 1.5, generating that pulse consumed hundreds of megajoules of electricity, and NIF can only do one shot per day. Most fusion experts give better odds to tokamaks, doughnut-shaped devices that use powerful magnetic fields to trap an ionized gas of the hydrogen isotopes deuterium and tritium and heat it to 100 million degrees Celsius so the nuclei crash together with enough kinetic energy to fuse. One big advantage ICF facilities have over tokamaks is that their different elements—lasers, reaction chambers, targets—can be developed and tested separately before they need to be combined.

The Longview system will be “hyper-modular. Each laser beam generated by a 10-meter-long box that can be replaced for upgrading or repair.

Focused Energy

Focused Energy is pursuing another variant of ICF, known as fast ignition, which uses two separate lasers to perform the functions of NIF’s single laser pulse: compressing the fuel and igniting the fusion burn. NIF’s fuel pellet must implode symmetrically to create a central spot hot enough to spontaneously ignite. Removing the need for a hot spot means the imploding drive can be gentler and requires “less stringent symmetry,” says Focused Energy’s Pravesh Patel, another NIF veteran. Fast ignition instead uses a second laser to kindle the burn once the fuel reaches maximum density. The second laser pulse, blasting in from one side, will hit a curved metal foil, generating a beam of protons that provides the spark.

Patel says the team wants to build a demonstrator in 8 to 9 years with a 100-beam compression laser producing 500 kilojoule pulses, one-quarter the energy of NIF’s. For the short ignition pulses, they plan to use lasers developed for Europe’s Extreme Light Infrastructure, a research facility. Each produces pulses of 1.5 kilojoules so Focused Energy will need 100 of them, combining their output into a single beam to set the fuel alight.

First Light Fusion

First Light Fusion will use a high-speed projectile to implode the fuel. An electromagnetic gun fires at up 20 kilometers per second to smash a small metal cube with a fuel capsule embedded inside. The cube has a complex internal structure of different metals that speeds and channels the resulting shock wave, wrapping it around the central capsule to compress the fuel.