Fusion boffins apply plasma know-how to building thrusters

'For a fusion company, it's quite nice to have a product that works'

UK boffins have used smarts gained through the development of fusion technology to fire up a thruster with the purpose of eventually cutting interplanetary travel times.

The UK-based Pulsar Fusion team showed off the thruster last month, a slightly alarming ring of plasma burning at millions of degrees in a vacuum chamber, confined by an electromagnetic field and spewing out particles at speeds of over 20km/s.

The Register spoke to the company's CEO, Richard Dinan, about the milestone and when its thrusters might make it off-planet.

We first chatted to Dinan back in 2018, when the company was known as Applied Fusion Technology and endevoured to get a small fusion reactor online ahead of the monstrous International Thermonuclear Experimental Reactor (ITER).

Youtube Video

Beset by ballooning budgets, ITER is a hugely expensive project to prove the feasibility of fusion as a power source. Kicked off in the 1980s, the organisation celebrated the start of machine assembly last month and expects its first plasma in December 2025.

Dinan's considerably smaller-scale facility has been running for a year and a half, and to demonstrate the team's ability when it comes to the control of the electromagnetic fields needed to keep the plasma confined, has come up with a thruster which it hopes to commercialise.

"For a fusion company," he told us, "it's quite nice to have a product that works."

Ball of conFusion

Indeed. Fusion technology has been characterised over the years by some very big, and somewhat empty, promises made by its proponents.

Pulsar, being a private venture, could always use the revenue stream as it seeks to realise some of its bigger dreams.

The facilities built for fusion research have proven handy for developing the thruster, which can be scaled up and down as applications require. Dinan also told us that the team opted for krypton rather than xenon for the propellant, noting that the former was "taking over" from the latter, which has historically seen use in Hall-effect thrusters.

Dinan pointed to the likes of US-based Orbion, which will build a thruster to meet the mission requirements using parameters such as required Delta-V and spacecraft mass. He intends that Pulsar will do similar for the UK space sector. "The UK," he said, "makes all these claims about wanting to be earning X [sic] per cent of the world's space sector."

"But it's kind of a dream," he added, since many applications require imported engine technology. Hence Pulsar's homegrown variety, designed on the back of fusion experience.

Impressive videos a viable product do not make, and a cynic would be forgiven for wondering when Pulsar's thrusters will see action in space. Dinan hopes to see cubesats using the company's krypton thrusters as soon as next year.

With traditional chemical rockets still needed for launches, Dinan also has an eye on further tweaks for Pulsar's technology: "One of the projects we're building," he said, "is to put a sort of more conventional thruster inside our Hall-effect thruster so that you can start launching in the atmosphere."

There remains the bigger picture. While Pulsar's krypton thrusters will do for pootling about in orbit or around the solar system – SpaceX famously uses krypton Hall-effect thrusters on its Starlink satellites – Dinan said he plans to scale things up as soon as 2022 with a much larger, next-generation bit of hardware.

"If you want to start going out of the solar system, you need something a lot more powerful," he said, adding that the company's mission is on propulsion through fusion energy, with the potential to cut mission times to Mars by half or potentially leave the solar system.

Heady stuff.

Dinan's aim is to have shown off a fusion rocket engine in space ahead of 2025's ITER demonstration. Back in 2018, he told us that he hoped to have his reactor online in four years. We'll take a 2022 demonstration of that bigger thruster, derived from plasma physics and fusion technology, as mission successful. ®