With ‘smoke ring’ technology, fusion startup marks steady progress – Science Magazine


With ‘smoke ring’ technology, fusion startup marks steady progress – Science Magazine

TAE Technologies’s Norman

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TAE Technologies’s Norman device can keep a ring of plasma spinning 100 times longer than its natural lifetime. Next stop fusion?

TAE Technologies

By Daniel Clery

A private company betting on an innovative fusion technology announced today that its latest device can sustain high temperatures for long reaction times—a major step toward a reactor capable of producing more fusion energy than is consumed by the device. The company, TAE Technologies, is still far from that goal, which huge government efforts are also pushing toward. But its achievements so far have drawn $880 million in investment—more than any other private fusion company. The company also announced plans to scale up to a larger machine, which it hopes will reach fusion conditions by 2025.

“The results look like steady progress, but it’s a long way from a fusion device,” says plasma physicist Cary Forest of the University of Wisconsin, Madison. Nevertheless, he adds, “I’m in the supporters camp.”

Fusion holds the promise of carbon-free energy, generated from abundant fuels and producing limited radioactive waste. But for more than 7 decades, the goal has been elusive: It requires extreme temperatures to coax nuclei to overcome their natural repulsion and fuse. Most publicly funded efforts have focused on tokamaks, which use powerful magnetic fields to imprison ionized gas in a doughnut-shaped vessel, where the plasma can be heated with microwaves and particle beams. The giant ITER reactor under construction in France is the pinnacle of that approach. At other labs, such as the U.S. National Ignition Facility, researchers crush tiny pellets of fuel with powerful laser pulses to spark a burst of fusion.

Founded in 1998, TAE has an alternative approach. Its machines whisk up a hydrogen plasma into a spinning smoke ring called a field-reversed configuration (FRC). The whirling motion of the charged particles in an FRC generates a magnetic field that helps confine the plasma inside it. Left alone, the vortex disintegrates in a fraction of a millisecond but TAE helps FRCs survive by firing a beam of particles tangentially into the edge of the ring, stiffening it and making it spin faster.

In TAE’s latest machine, operating since 2017 and dubbed Norman after company co-founder Norman Rostoker, FRCs take shape in a 30-meter-long tube that bristles with controlling magnets, sensors, and particle injectors. TAE now says Norman can sustain FRCs for 30 milliseconds and heat them with particle beams to temperatures of about 60 million degrees Celsius—better by factors of 10 and eight, respectively, than the company’s previous devices. And, CEO Michl Binderbauer says, “We can hold it as long as you want.” He says the FRC lifetime is limited only by the amount of power they can store on-site to run Norman’s magnets and particle beams and keep the rings spinning.

TAE has not published its results, announced in a press release today. But others are impressed by the progress. “They have focused goals and deliver on time, and that has been lacking in fusion for a while,” says fusion scientist Dennis Whyte of the Massachusetts Institute of Technology. “They’re getting closer to the conditions necessary for [energy] gain,” he says. But he points out a few challenges. The electrons in Norman’s FRCs are cooler than the rest of the plasma, at just 10 million degrees Celsius. Cool electrons cause drag on the incoming particle beams, reducing their effectiveness. The FRCs are also leaking heat too fast. Whyte says TAE will have to improve heat retention 1000-fold if it is to reach its goals. “It’s good progress but there’s still a way to go,” he says.

Whyte adds that plasma physics also has a habit of springing surprises. “Up to now, TAE hasn’t seen a showstopper,” he says, “but you don’t know until you see it.” In the 1980s, for example, researchers built large tokamaks they thought would be big enough to produce excess energy. But an unforeseen phenomenon called microturbulence appeared in the plasmas, causing them to shed heat faster than expected.

Binderbauer says TAE is confident its next machine, dubbed Copernicus, will get it to the next milestone: 100 million degrees Celsius, the temperature at which traditional fusion fuel—a mixture of the hydrogen isotopes deuterium and tritium—starts to fuse. Copernicus will be up to 50% larger than Norman, and will come with a power supply able to sustain FRCs for several seconds. TAE plans to start building the $250 million device later this year at a new site near its current facility in Foothill Ranch, California.

But the company doesn’t plan to stop there. Tritium fuel has drawbacks: It is radioactive and hard to acquire; and the deuterium-tritium reaction produces high energy neutrons, requiring thick shielding to protect the machine and its operators. TAE wants to use an alternative fuel of hydrogen and boron, plentiful elements that produce many fewer neutrons when they fuse. But that reaction requires temperatures of billions of degrees Celsius—and a future device larger than Copernicus, which TAE hopes to build by the end of the decade. “We’re pretty confident we have the theoretical basis,” Binderbauer says.

Investors appear to believe him. The company has attracted big name funders, including Paul Allen’s Vulcan Capital, Google, the Wellcome Trust, and the Kuwaiti government. Norman’s results alone have helped TAE raise $280 million, and Copernicus is already 50% funded. “Many people are very impressed by how they’ve opened up the wallets of venture capitalists,” Forest says. “If they can maintain this Moore’s law type progress, maybe they can get there.”