Gigantic, 70-Foot Nuclear Fusion Gun Could Change the World

On a quiet industrial estate in England, the silence is occasionally broken by the thump of a 72-foot-long gun. At the end of the barrel, a star is born.

The Big Friendly Gun (BFG) is a prototype for what U.K.-based nuclear fusion company First Light Fusion hopes will be the future of energy production.

The video above shows a test-fire at the company's facility. From a safe distance and separated from it by a thick wall of concrete, the team look on as data pours in from the gun's sensors. Each test-fire takes the world a step closer to what will potentially be an effectively limitless source of clean power.

The giant steel gun works by firing a high-velocity piston with 6.6 pounds of gunpowder. Speeding down the barrel, the piston, compressing hydrogen gas as it moves, enters a cone segment that crushes the gas to a tiny point before it bursts through a metal seal. This shoots a projectile at 4.3 miles per second into a vacuum chamber where it strikes a nuclear fusion fuel target, temporarily producing the conditions in which nuclei can fuse together.

Big Friendly Gun
The first stage of the Big Friendly Gun barrel. Behind the camera, the narrower second stage of the barrel leads to the reaction chamber. Photo taken in Oxford, U.K., on October 4, 2022. Ed Browne/Newsweek
Big Friendly Gun reaction chamber
The reaction chamber of the Big Friendly Gun. For scale, a human could squeeze inside it. A tiny projectile exits the small hole at several kilometers per second before hitting a nuclear fusion fuel target. Fusion has been achieved inside this chamber. Photo taken in Oxford, U.K., on October 4, 2022. Ed Browne/Newsweek

First Light Fusion says it was commissioned, designed, and built for £1.1 million ($1.27 million) over the course of 10 months. There's nothing else like it in the world.

The fusion of atomic nuclei is the same process that powers our sun, and scientists have been trying to recreate it on Earth for almost 100 years, since this reaction produces more energy than fossil fuels with no carbon emissions or radioactive byproducts.

Additionally, the fuels needed for the reaction, which are typically the hydrogen isotopes deuterium and tritium, can be produced artificially. As such, fusion power, if we can harness it, would be not just clean, but abundant.

First Light Fusion's approach—known as inertial fusion—is a far cry from perhaps the most common and much more complicated tokamak approach, in which plasma gas is circulated using giant magnets. But it works, and CEO Nick Hawker thinks it could change the game.

"I would describe tokamaks as the leading approach in magnetic fusion," Hawker told Newsweek. "The physics are pretty clear—it's been very well characterized."

Small reaction chamber
The reaction chamber of a smaller-scale version of the Big Friendly Gun. Photo taken in Oxford, U.K., on October 4, 2022. Ed Browne/Newsweek

Through all the years of studying tokamak technology, the principal issue is how the plasma loses energy. Scientists have found that energy within the plasma tends to bleed across the intense magnetic field lines involved in the reaction, causing the reaction to fizzle out. As such, no one has managed to achieve net energy gain—more energy generated than energy required to run the machine—with a tokamak.

"Net energy gain has been demonstrated with inertial fusion, but the driver, instead of being a laser, was an underground weapons test," Hawker said. "So there is that empirical proof there that you can get to high energy gain with inertial fusion.

"I feel a bit unfair giving this as a criticism of magnetic fusion because the challenges we know about are because of the work done in magnetic fusion, and that's what has allowed us to come up with an approach that sidesteps them."

One such challenge is the sheer violence involved in fusion reactions. Tokamaks must circulate plasma at temperatures of 180 million degrees Fahrenheit in order to generate fusion, all while neutrons from the fusion reaction are battering the inside walls of the reaction chamber.

"It's one of the major challenges for tokamaks—the survivability of the vacuum chamber and how frequently you'd have to swap that out," Hawker said. "It's like plastic that you've left in the sun. What happens when you leave plastic in the sun for a long time is that the UV light destroys the material structure within the plastic, and it falls apart in your hands. The neutrons from fusion do that to structural steel, so it's a bit of an issue."

Nick Hawker
Nick Hawker, CEO of First Light Fusion, stands in front of the company's M3 pulsed power unit, which uses extreme electromagnetic forces to launch projectiles at hypervelocity. Photo taken in Oxford, U.K., on October 4, 2022. Ed Browne/Newsweek

First Light Fusion's reactor design aims to sidestep this by shielding the reactor walls with liquid, which absorbs the neutrons and exposes the steel structure of the chamber to less neutron bombardment compared to a tokamak.

The BFG is only one step toward this final vision. The company is currently working on its next machine, M3, which is a sprawling mass of electric capacitors all geared toward using an electrical current to accelerate a projectile at 1 billion Gs to 20 kilometers per second, upping the impact speed. In short, it's more sophisticated than gunpowder.

M3 machine
Stacks of electronic capacitors that power the M3 propulsion machine. There are 192 in all, producing up to 200,000 volts. Photo taken in Oxford, U.K., on October 4, 2022. Ed Browne/Newsweek
M3 machine targets
A before-and-after version of the projectiles used in the M3 machine. On the left: A projectile that has been subject to the machine's intense electromagnetic forces. On the right: One that has not. Photo taken in Oxford, U.K., on October 4, 2022. Ed Browne/Newsweek

When Will Fusion Energy Be on the Grid?

Hawker expects the First Light Fusion reactor to be generating usable electricity in the 2030s and for power to be on the grid by the following decade. So what would a giant gun reactor look like?

"I like to say that magnetic fusion is like a furnace," Hawker said. "It's an always-on hot process because the particles are going around the donut. Whereas inertial fusion is more like an internal combustion engine. It's a pulsed process where you have a repetition rate and the energy per event multiplied by the frequency gives you the power."

This analogy can be continued when considering that internal combustion engines have a spark plug that ignites the gas to keep the process going. Often in inertial fusion this spark plug is a laser. In the case of First Light Fusion, it is a high-velocity projectile. According to Hawker, this method benefits from being cheaper and simpler.

The projectile hits the fusion target rapidly. The company's target design amplifies this impact pressure to around 1 terapascal or 10 million times more pressure than Earth's atmosphere, producing a cloud of heat and neutrons. This heat is then transferred to a flow of liquid that moves around the inner reaction chamber and is transferred once more to a tank of water, heating it to a temperature of over 1,000 degrees Fahrenheit.

"We love steam," Hawker said. "It's low risk, it's easy. I want a very boring power plant design, and I want one new thing only, which is the core process. Everything else I want to be as standard as possible."

In First Light's hypothetical reactor on the grid, this process is expected to repeat itself once every 90 seconds—not as fast as some other inertial fusion proponents, which envision laser-based reactors repeating their reactions 10 times per second. Still, even one kinetic impact once per 90 seconds is enough to release huge amounts of power.

"Each target will release about the same amount of energy as a barrel of oil," Hawker said. "It's literally a million times more energy dense than a chemical reaction. It's more energy dense than nuclear fission as well."

The next decade is a long way off, and the climate crisis demands a sharper change to our energy habits than fusion can currently promise to provide. But the world needs a breakthrough energy technology and late is better than never. To that end, Hawker and his team continue to put their fingers in their ears and press "fire."

Plasma
A file illustration depicting plasma, which is a superheated state of matter in which nuclear fusion can occur. Nuclear fusion requires huge amounts of heat and pressure which scientists try to recreate in labs. sakkmesterke/Getty