Evrim Yazgin
Cosmos science journalist
A New Zealand company has become the first in the nation’s history to turn on a fusion machine.
OpenStar technologies reached a crucial milestone in the development of nuclear fusion-first plasma. This is the moment a fusion device creates and confines a super-hot cloud of ionised gas.
Nuclear fusion is the process by which stars generate energy. Extreme temperatures and pressures in a star’s core force the nuclei of atoms to fuse together. This releases huge amounts of energy. Replicating this process on Earth could resolve energy problems, but such a fusion reactor remains a thing of the future.
Temperatures of more than 100 million degrees Celsius are required to fuse of atoms on Earth.
“At OpenStar, we’re trying to build this thing called a levitated dipole and we’ve just achieved our first plasma,” nuclear physicist and OpenStar founder and CEO Ratu Mataira tells Cosmos.
A dipole is a system where the positive and negative charges are separated.
“Dipoles are the only configuration of plasma that you can build in a lab or in an industrial setting, and find stably arranged in nature,” he adds. “That gives us a foundation to think we can scale this up, put more heat into it and build a fusion machine. But what we’ve effectively turned on most recently is a magnetosphere inspired by the magnetospheres around planets.”
Not your typical fusion machine
The goal is to have a plasma which is levitating so that it doesn’t interfere with and damage the fusion device. But this first plasma at OpenStar is supported by a cradle, Mataira says.
“When you try to confine plasma, you’re trying to take something that has a lot of energy and wants to go off in a direction – like toward the wall of your device – and you provide a magnetic field that takes some of that energy and redirects it into a curved path,” Mataira explains. “That takes care of a lot of the problem. But what that particle can still do is spiral along the field lines of your magnetic arrangement.”
Mataira says that more common fusion device designs like tokamaks or stellarators try to confine those magnetic field lines within the machine and not touching anything. The New Zealand team’s design based on planet magnetospheres is different.
“In a magnetosphere or planet, you have something to touch. These particles eventually find their way to the poles of a planet. That’s what we call the Aurora Australis and Borealis. And in our experiment, that’s also true. Those highest energy particles make their way to the support structure of our system, and that ultimately suppresses the temperatures that we can produce.
“We can solve that with levitation and then get into the deeper, unsolved problems around dipoles that we want to test in our next machines,” Mataira says.
While the OpenStar machine uses the same basic principles of magnetic fields to hold a plasma in place, Mataira says there are some other key differences.
“Our relationship with instability and turbulence is basically the complete opposite of a tokamak,” he says. “In these other types of machines, turbulence or instability kills your machine or kills your performance.
“In the case of a tokamak, you have these things called disruptions, where all the stored energy of that plasma can find its way into the wall of the device and basically blow it up. You also have turbulence, which, as you’re trying to get the core really hot, takes that heat the plasma moves around, and then just puts that heat out into the edge. You can’t hit the temperatures that you need.”
In contrast, a levitated dipole system doesn’t have a lot of stored energy called “plasma current”, Mataira says. “So you don’t get these big bursts of energy whacking into things.”
A very attractive prospect
Mataira says OpenStar is one of a growing number of companies worldwide using high-temperature superconductors (HTS) to build their magnets. These HTS magnets are made of rare-earth barium copper oxides, or ReBCOs.
This material has the potential to produce magnetic fields of about 20 Tesla (T), though the current prototype hasn’t hit that strength yet. For comparison, in 2022, Chinese researchers created the world’s strongest steady-state magnet which had a strength of 45.22 T. The Earth’s magnetic field is about a million times weaker than these magnets.
“These HTS magnets have a lot of engineering challenges, and they’re quite different to the previous generation of superconducting magnet,” Mataira says. “The fusion community broadly thought that the magnet engineering was impossible, and that getting one of these HTS magnets to work without being connected to a power supply over time was going to be too difficult.
“Our answer was to include superconducting power supplies on board. It’s cutting-edge technology straight out of the university lab, now demonstrated in an industrial setting. That allows us to energise the magnet with an onboard power supply so that it can continue to operate while there’s a plasma around it and we’ve disconnected everything else.”
The operating temperature for the superconductor is 90 Kelvin (–183°C), Mataira says. “But the colder you make them, the better they perform. … Our current prototype works at a design temperature of 50 K (–223°C).”
“Because the plasma is macroscopically stable, and turbulence is not the enemy and all these things, there’s nothing about the plasma physics that actually limits the pulse length you can run these things. In the plasmas that we were running, we ran 5 shots, they were 5–20 seconds. And the reason why we’re running them so short is just because we want to be able to twiddle the knobs, and that’s long enough for us to get the data,” Mataira says.
A homecoming for fusion
Mataira says that, despite the first two people being able to achieve fusion in a lab being an Australian and a New Zealander, neither country has advanced the development of fusion machines over the following decades.
“Ever since kiwi tech contributed critically to Commonwealth Fusion System’s (CFS) early success, it was clear that they had deep physics and engineering expertise with HTS and its applications,” says Professor Dennis Whyte (not involved in OpenStar), former director of MIT Plasma Science and Fusion Center (PSFC) and co-founder of CFS.
“It is a natural fit that OpenStar has been built by a team that will leverage that expertise in HTS. I’m thrilled that they are building high-performance levitated superconducting dipoles from HTS, since this adds an exciting option to the diverse approaches to fusion. First plasma is a critical milestone and I’m looking forward to their progress.”
“OpenStar developing here is really the first dedicated fusion effort that we’ve seen, although it’s born out of work that was happening in research labs that was fusion adjacent on magnet technology and other fusion companies and projects,” explains Mataira.
Mataira says that there are risks associated with dipole technology because it is a much younger field with fewer machines built worldwide.
“But the engineering advantages are so clear. If I want to make my magnet better, I build a new magnet on the bench, take the old magnet out, put the new magnet in. It takes me about a week. If you were doing that in tokamak land, you’re looking at a new tokamak that’s a 5- or 7-year build. You’re fighting for funding for 3 years, maybe more. The iteration pace on the other concepts is really difficult, but in dipoles we think we can make really rapid progress,” he says.
Mataira is hopeful that nuclear fusion is on the horizon and that OpenStar’s progress will contribute to tackling energy challenges in society.
“I think a reactor will hopefully produce electricity sometime in the 2030s. The question which keeps me up at night a little bit more is the how these different fusion concepts, including ours, are going to build enough machines to really matter. It really does need to be the 2030s because to get the 2050 goals that we need to decarbonise. You need time to build things – and a lot of things. We think we have advantages there. But yeah, you wake up every morning and you go, okay, the clock is ticking today.”
Cosmos Education and Double Helix Extra, with the Australian Institute of Physics, are challenging the world’s scientists, writers and communicators to help teach kids about quantum science. Find out how to submit entries to the competition here.
