Günter also said that even the best start-ups investigating alternatives to tokamaks that still use magnetic confinement are “operating in plasma regimes that correspond to tokamak performance several decades ago,” or are having problems that tokamaks never had. Her sharpest criticism, though, is for start-ups pursuing fusion reactions that aren’t based on deuterium and tritium. “For the moment,” she told me, “and I’m talking probably for a one-hundred-year period—they’re completely unrealistic.” Such a gap between rhetoric and reality may threaten all fusion efforts.
What do the fusion start-ups themselves think of the risk that one of them breaks their promises in a very public way? Tokamak Energy’s David Kingham thought the benefits far outweighed the risks. “Private sector fusion grows the pie,” he told me. But that doesn’t mean he didn’t have any concerns: “There’s a risk of a cold fusion–type idea emerging, and you do see that from time to time. Because fusion is exciting and complicated there’s a risk of insubstantial or fraudulent ventures emerging. There are one or two particular firms who haven’t been allowed to join the fusion industry association.”
David Kingham wouldn’t tell me which firms. He doesn’t have concerns about Tokamak Energy’s sponsors being spooked, because “our investors are sophisticated.” Nick Hawker tells me exactly the same thing. “If there was a high-profile failure that could discourage some investors, yes,” he admits, “but we’re fortunate because our investors get it and have been through bubbles before.”
The strength of competition is such that they all think they’re the only ones who will deliver fusion on time and well below the costs that governments are shelling out for.
Governments Are Behaving Like Start-ups to Stay in the Race
Don’t count out the government laboratories yet though—they’re adapting too. One of the early designs for a magnetic confinement fusion reactor that was out of favor for years, the stellarator, is now back in the race for fusion thanks to a project run by the Max Planck Institute for Plasma Physics, where Professor Sibylle Günter is the scientific director. The staff there has built the world’s most advanced stellarator, Wendelstein 7-X (also known as W7X).
Stellarators solve the problem of particles in the plasma drifting out of confinement with a twist, literally. Instead of twisting the particle orbits around the inside of the tube with one externally applied magnetic field and another field generated by a current in the plasma, stellarators use a twisted combination of externally applied magnetic fields to guide the plasma inside the tube into doing helical twists. The magnetic field twisting is delicately balanced to cancel out the drift of particles toward one wall or another.
“The stellarator concept seemed doomed for a long time,” Sibylle told me, “because experiments showed that particles, and thus energy, got lost too fast.” But, she says, a better theoretical understanding of plasmas led them to realize there were conditions that wouldn’t suffer this loss of confinement, and, in principle, they could build a device to those specs. However, creating the perfect, twisting magnetic fields—and fitting in the energy-hungry coils that generate them—is a tall order in practice, even if it’s possible in theory. To make it work requires that the magnetic field be so perfect that the deviations are no bigger than one part in one hundred thousand.20
Stellarators are back in steel and concrete because two technologies brought the seemingly impossible requirements into reach. The rapid development of supercomputers has meant that star builders are able to design and simulate reactors with just the right twists and turns in the magnetic field to keep particles on track. The second technology is superconductivity, which means it’s possible to create enormous magnetic fields without using too much electrical power.
Sibylle told me more about the design of the machine, which was completed in 2015. “Wendelstein 7-X is the first optimized stellarator of sufficient size to demonstrate that stellarators can achieve confinement properties similar to tokamaks,” she says. And the confinement properties of tokamaks are close to what is needed for net energy gain. Unlike in tokamaks, the magnetic confinement is solely provided by external coils, with no plasma current. Fifty superconducting niobium-titanium coils, each 3.5 meters (approximately 11.5 feet) high and cooled by liquid helium, wrap around the helically twisting reactor torus to provide this field. While it’s not what you’d call a compact machine, it’s not huge either, measuring about 16 meters (approximately 52.5 feet) across. Sibylle says that stellarators have the potential to be stable and easy to control—not sentiments that you hear in relation to tokamaks.
This small(ish) star machine is more what you would expect from a fusion start-up than a collaboration between the German government, the EU, and the US national laboratories. Within just a few years of operation, it had smashed through the previous stellarator record for fusion conditions with a combination of temperature, density, and confinement time that is 6 percent of what Lawson’s famous equation predicts is needed for net energy gain. This is impressive stuff for a technology that was largely abandoned by the world following the then USSR’s success with the tokamak (the then best stellarator in the US, the Model C, was ignominiously converted into a tokamak).21
Although it’s a government-run machine, W7X has achieved successes that show why private fusion can’t be counted out. New technologies allow for schemes that were once thought to be forever out of the running to be competitive again. W7X also demonstrates how smaller machines can catch up on decades’ worth of progress.
Stellarators aren’t the only machines that have received renewed attention from government laboratories. The fusion machine that Tokamak Energy is using, the stouter and more apple-shaped version of a tokamak, called a spherical tokamak, originated in government fusion programs and is suddenly back in fashion with state-supported scientists. I asked Ian Chapman, the scientist-cum-civil-servant with a politely frank manner and an unwavering belief in the good that fusion can do, what he would say as CEO of the UK Atomic Energy Authority if the EU or the British government said, “We want to accelerate fusion and we’re going to give you the money: what will you do?”
“What we’d really like to do,” he told me, “is explore the spherical tokamak as a reactor path and build a machine on JET scale that produces net electricity. JET was about £2 billion in today’s money and took four years. If we built a spherical tokamak on that scale, it would cost more than £2 billion, but not twenty, and we could build it in less than a decade [once designed]… It would be exciting to try a smaller, cheaper, more compact reactor.”
This is almost exactly what Tokamak Energy is trying to do, though they think they can do it with “just” £700 million (approximately $930 million). Spherical tokamaks, which give more bang for the buck in terms of magnetic field strength, simply weren’t around when JET was first conceived. Ian tells me that the low-risk, low-commitment funding of fusion followed by governments since the early 1990s has necessarily meant that star builders have stuck with conventional tokamaks, partly because they’re tried and tested. However, Culham has already cut its teeth on a small, experimental spherical tokamak that can reach 10 million degrees Celsius (18 million degrees Fahrenheit), called MAST Upgrade. Ian favors spherical tokamaks as a second strand now because they have a clear confinement advantage over the conventional machines. That said, they come with more risks—no one has ever built one at a scale even close to being relevant for power production. And precisely because they’re more compact, all of the difficulties of dissipating the heat from fusion are exacerbated, calling for more complex heat exhaust systems.22
A few weeks after I visited Ian in his Portakabin-like office at the Culham Centre for Fusion Energy, the British prime minister had exactly the same conversation with him. Ian Chapman stayed true to his answer, and now there’s £220 million ($396 million) to fund the initial design (not the construction) of what is being called the Spherical Tokamak for Energy Production, or STEP. It’ll be just ten meters (approximate
ly thirty-three feet) in diameter, a little bigger than JET, but—if built—would be designed to safely go beyond net energy gain and deliver around one hundred megawatts of power to the grid. It’s not clear if Ian’s having such a well-practiced answer when the PM asked his question contributed to his funding success.23
Another new government scheme with promise is MagLIF, short for magnetized liner inertial fusion. Sandia National Laboratory sits in the outer suburbs of Albuquerque, New Mexico. Like Livermore, it’s part of the USA’s National Nuclear Security Administration. While Livermore has become the world’s center of excellence in high-energy lasers, Sandia stuck with pinches similar to those first tried out as long ago as the 1940s.
Like Livermore, Sandia uses its biggest machine—“Z”—for a combination of open science and secret experiments related to nuclear weapons. It’s the machine that Omar Hurricane, NIF’s chief scientist, learned his craft on. It’s the type of machine that Louisa Pickworth developed her diagnostic skills on before turning them to the implosions on NIF. The name Z derives from the machine’s so-called Z-pinch. Instead of pinching plasma around a ring, Z pinches plasma in a vertical column.
Scientists at Sandia had the idea that they could use Z’s capabilities for fusion. They take an empty beryllium can, which looks like a miniature baked beans can at just 1 centimeter high and 6 millimeters (less than an inch) in diameter, and fill it with deuterium and tritium. Then, they hook it up to the middle of Z and whack an absolutely enormous magnetic field—ten to thirty Tesla—through the can lengthwise. This is equivalent to at least seven MRI machines, or, putting it in Ig Nobel Prize terms, it’s enough to levitate a frog.I A laser beam enters through a window in the top of the can, heating up the deuterium-tritium fuel to 3 million degrees Celsius (5.4 million degrees Fahrenheit)—not hot enough for fusion, but hot. Then comes the pinch: eighteen mega amperes of current travel through the beryllium can, generating an outer invisible can made up of magnetic fields. The current and the fields interact, and the pinch comes, squashing the can and the fuel with it for more than one hundred nanoseconds. The squishing causes the magnetic field inside the can to be amplified, reaching an extraordinary ten thousand Tesla. And, as is intended, the density and temperature ramp up too, with the nuclei reaching 30 million degrees Celsius (54 million degrees Fahrenheit). Fusion occurs (neutrons have been detected), and the fast particles that come screeching out of the reaction are bound by the magnetic fields so that they stay in the fuel, heating it further.24
It’s a great idea for a fusion scheme. Sandia’s simulations from 2012 show that a current of sixty mega amps would give a fusion gain of one hundred times the energy put in. Not so fast though! This is plasma physics after all. While Sandia doesn’t have a machine big enough to try this out, even the preliminary experiments on Z showed that can compression was rife with instabilities. Just as with every other fusion scheme under the Sun, the practice is harder than the theory.
There are no fusion schemes without enormously complex physics and real head-scratchers to overcome: there are just fusion schemes that haven’t been fully explored yet. Magnetized inertial fusion is promising, and a good example of how even supposedly slow-moving government laboratories can innovate, but it’s got a long way to go to work out the kinks.
It doesn’t have to be competitive. Because they have different strengths and weaknesses, the best solutions are likely to come from the private and public fusion sectors working together. After all, SpaceX has flourished because of its relationship with NASA, not in spite of it. Both types of star builder need to work together to create a regulatory environment that recognizes that fusion is distinct from fission (and the US Congress is listening).25
Ian Chapman is, sensibly, convinced of the need for public-private partnership.
“Five years ago we went to Rolls-Royce and firms like that and said ‘can we work with you.’ ” At that time, the firms said no because they thought fusion was too early stage, he explained. “Now they’re coming to us and asking how they can win fusion contracts,” he continued. “You need the private sector for investment. A billion in the last ten years raised from private companies; venture capitalists, philanthropists, sovereign wealth funds, and, recently, energy companies: oil and gas firms.”
Currently, the new star builders are behind the government laboratories in reaching a 100 percent energy gain from fusion. None have come close to JET’s fusion energy record, nor NIF’s best single-shot energy yield of 3 percent. Equally, they haven’t had decades to do fusion, or the same level of funding. They’re making rapid progress, though. And, if nothing else, they’re forcing everyone to up their game.
So the race to build a star may yet be won by a maverick working in an unassuming warehouse somewhere near you.
And if you think that someone tinkering with a nuclear device in your backyard sounds, well, just a little bit dangerous, that’s understandable. When I asked her what people should know about the race to build a star, Sibylle Günter shot back, “It’s difficult—don’t try it in your backyard.” She does have a point. After all, the pistol shrimp’s claw is a weapon. So let’s find out if we need to worry about what our nuclear neighbors, the star builders, may be up to in your backyard.
I. Frogs aren’t usually magnetic, but with a strong enough magnetic field, they can be. Physicist Andre Geim won an Ig Nobel Prize (a satiric prize given to honor unusual, imaginative, even trivial achievements in scientific research) for demonstrating this in 2000; ten years later he’d win the real Nobel Prize for Physics for work on graphene, a sheet of carbon that’s just a single layer of atoms thick.
CHAPTER 8 ISN’T THIS ALL A BIT DANGEROUS?
“The fact that no limits exist to the destructiveness of this weapon makes its very existence and the knowledge of its construction a danger to humanity as a whole. It is necessarily an evil thing considered in any light.”
—Enrico Fermi and Isidor Rabi discussing the hydrogen bomb in a report on behalf of the General Advisory Committee of the US Atomic Energy Commission, 19491
One day before dawn in the early spring of 1953, Matashichi Oishi stood on the deck of the Lucky Dragon No. 5 watching the fresh salty spray of the Pacific Ocean crash over the sides of the boat. He was twenty years old and working as a fisherman. It was the only life Matashichi Oishi really knew—he’d been doing it since he dropped out of school at age fourteen, and he had no other experience of the world. He and twenty-two other Japanese crew had been at sea for five weeks, sailing through nothing but open, empty ocean for most of that time.
The Lucky Dragon No. 5 was a thirty-meter long (about ninety-eight feet) fishing boat that was barely seaworthy. There was little machinery, and everything had to be done by hand. It was hard, perilous labor. They’d been unlucky throughout the tuna-catching trip, beginning when they temporarily ran aground and continuing when they lost half of their trawling nets to the waters.
On the morning of March 1, 1953, they were attempting to make one last haul before returning home. As Matashichi stood on the deck with the sea breeze in his hair, and the milky radiance of billions of stars overhead, there was a sudden and all-pervasive bright light.
“It emerged from the horizon from the west, from the east, and from every direction,” Matashichi Oishi said. “It wasn’t a flashing, it was like the light was flowing and covering the whole area. I thought it was some kind of natural disaster.”
The crew all stopped to look in awe as the night took its leave early. No one spoke as they watched the spectacle. Seven minutes later, a sound arrived: a deep rumbling, like continents colliding, that rose from the bottom of the ocean. The crew unfroze, and everyone, including Oishi, dived to the deck, some crawling to the cabin to hide. The sound passed, and it then went very quiet. But their ordeal was only just beginning.
Next came a biblical rain of stark white powder from the sky. It fell everywhere; onto the sea, onto the deck, onto the crew of the Lucky Dragon, and even onto Oishi’s fac
e.
“I didn’t feel any danger,” Oishi said, “because it didn’t leave any mark.”
It wasn’t snow. Curious as to what it might be, Oishi tasted it. He realized it was ash. It was crunchy. What the unlucky inhabitants of the Lucky Dragon No. 5 didn’t realize yet was that they’d been showered in tiny flakes of radioactive coral. With the boat covered in white radioactive ash, the crew hauled up the fishing nets and set course for Japan and their home port of Yaizu. On the way back, they began to feel strange.
“We were dizzy and some people started having diarrhea. The places where white ash had landed started swelling and lots of large blisters began appearing.”
The journey back across the Pacific, past the edge of the Marshall Islands where they’d last laid anchor, took several days. After four days, their hair began falling out.
As soon as the boat returned to harbor, scientists and physicians realized what had happened to the crew. They had acute radiation syndrome. They were all hospitalized. One crew member died within six months, the others spent a year in the hospital recovering, but they were all plagued by health problems long after. Oishi would get liver cancer. Many would have their lives shortened.
Around eighty miles west of where the Lucky Dragon No. 5 had been sailing that day in 1953 was Bikini Atoll, a slight ring of coral protruding out of the ocean that was at the northern end of the Marshall Islands. At 6:45 a.m., the United States had exploded a fission-and fusion-powered hydrogen bomb called Castle Bravo that blew a one-mile-diameter crater through the atoll’s coral ring. The device used an initial chemical explosion to drive together fissionable isotopes (special types of plutonium or uranium) so that they reached a critical mass at which a fission explosion occurred. The energy from the first fission stage drove a small sphere of deuterium and tritium to a high enough temperature and density for fusion reactions to start. This second, fusion stage triggered yet more fusion reactions in a rod of material and unleashed vast numbers of neutrons that caused even more fission reactions. Each stage released truly fearsome quantities of energy that combined to make it the largest bomb in human history up to that point in time.
The Star Builders Page 16
