Magnetic fusion requires massive heat and is still not sustainable for energy use.
Deuterium is crammed into all the empty spaces in an existing metal structure.
NASA has unlocked nuclear fusion on a tiny scale, with a phenomenon called lattice confinement fusion that takes place in the narrow channels between atoms. In the reaction, the common nuclear fuel deuterium gets trapped in the “empty” atomic space in a solid metal. What results is a Goldilocks effect that’s neither supercooled nor superheated, but where atoms reach fusion-level energy.
“Lattice confinement” may sound complex, but it’s just a mechanism—by comparison, tokamaks like ITER and stellarators use “magnetic confinement.” These are the ways scientists plan to condense and then corral the fantastical amount of energy from the fusion reaction.
In a traditional magnetic fusion reaction, extraordinary heat is used to combat atoms’ natural reaction forces and keep them confined in a plasma together. And in another method called “inertial confinement,” NASA explains, “fuel is compressed to extremely high levels but for only a short, nano-second period of time, when fusion can occur.”
By contrast, the lattice is neither cold nor hot:
“In the new method, conditions sufficient for fusion are created in the confines of the metal lattice that is held at ambient temperature. While the metal lattice, loaded with deuterium fuel, may initially appear to be at room temperature, the new method creates an energetic environment inside the lattice where individual atoms achieve equivalent fusion-level kinetic energies.”
The fuel is also far more dense, because that’s how the reaction is triggered. “A metal such as erbium is “‘deuterated’ or loaded with deuterium atoms, ‘deuterons,’ packing the fuel a billion times denser than in magnetic confinement (tokamak) fusion reactors. In the new method, a neutron source ‘heats’ or accelerates deuterons sufficiently such that when colliding with a neighboring deuteron it causes D-D fusion reactions.”
With atoms packed so densely within the atomic lattice of another element, the required energy to induce fusion goes way, way down. It’s aided by the lattice itself, which works to filter which particles get through and pushes the right kinds even closer together. But there’s a huge gulf between individual atoms at energy rates resembling fusion versus a real, commercial-scale application of nuclear fusion.
On Tuesday, scientists at Lawrence Livermore National Laboratory announced that they had achieved nuclear fusion “ignition,” but truly limitless energy is still a ways off.
National Ignition Facility
Scientists at the Lawrence Livermore National Laboratory’s National Ignition Facility (NIF) achieved a breakthrough in nuclear fusion known as “ignition.”
Ignition, or “scientific energy breakeven,” occurs when the energy input into a nuclear fusion system is less than the energy gained.
This breakthrough proves that fusion can be replicated on Earth and provides a glimpse of nuclear fusion’s potential as a clean energy source.
As Earth steadily warms, the search for alternate forms of clean energy is heating up with it. On Tuesday, the California-based Lawrence Livermore National Laboratory (LLNL) and the U.S. Department of Energy announced a breakthrough achievement in one of science’s more far-flung attempts at limitless energy—nuclear fusion, the science behind the continuous thermonuclear reaction that lies at the center of our sun.
On December 5, scientists at the laboratory’s National Ignition Facility (NIF) achieved a “scientific energy breakeven,” otherwise known as “ignition.” This means that after bombarding a pellet of frozen deuterium and tritium with laser beams, more energy was produced than went into generating the fusion reaction in the first place.
“The pursuit of fusion ignition in the laboratory is one of the most significant scientific challenges ever tackled by humanity,” LLNL Director Kim Budil says in a press statement. “Crossing this threshold is the vision that has driven 60 years of dedicated pursuit.”
There are many ways scientists are exploring how to power the world with nuclear fusion. The most familiar method involves stellarators or tokamaks, donut-shaped reactors that trap superheated hydrogen plasma (so hot it can even damage the reactor) in magnetic confinement until their nuclei fuse, flinging neutrons outward and producing energy. However, NIF’s approach, called “inertial confinement,” is radically different and uses lots and lots of laser beams—192 of them to be precise.
Scientists power up and shoot these beams at a cylinder that’s about the size of a pencil eraser. Inside that cylinder is a pellet of deuterium and tritium (which both fuse at lower temperatures and produces more energy) that subsequently implodes. As the hydrogen with helium fuses, it produces energy. For more than a decade, this power transfer—or the amount of energy needed to induce this fusion—exceeded the energy extracted from the experiment. That is, until this week. According to the U.S. Department of Energy, NIF scientists produced 3.15 megajoules (MJ) out compared to the 2.05 MJ of energy put in. For some context, about 3 megajoules can power a one-kilowatt microwave oven for about an hour.
“This sets fusion energy up as a possible energy source for the future,” Mickey Wade, director of Oak Ridge National Laboratory’s Fusion Energy division, tells Popular Mechanics. Unaffiliated with NIF, Wade works closely with the International Thermonuclear Experimental Reactor (ITER), a nuclear fusion tokamak. “Now we have to figure out how to take that up to another scale in terms of large amounts of energy production.
The road to this encouraging result is decades in the making. Construction on the NIF began back in 1997 and the first experiments didn’t get underway until 2009. At the time, NIF physicist Siegfried Glenzer was confident ignition would be achieved within the year, but that overly ambitious deadline came and went.
Over the next 12 years, NIF scored a series of small victories including one as recently as 2021 when it announced that the lab produced a burst of 10 quadrillion watts of power, or about 70 percent of the energy needed to fire the laser. However, that “burst” (or a miniature hydrogen bomb, depending on your point of view) only lasted 100 trillionths of a second. However, with the NIF’s achievement of ignition, Wade says the promise of nuclear fusion is more real than ever.
“What’s different today than 20 years ago is that our knowledge base and our ability to simulate these fusion plasmas are light years ahead,” Wade says. “The pace of advances in the next 20 years will be faster than it has been in the past.”
But the NIF’s announcement doesn’t mean we’ll suddenly be swimming in free energy. For one, while the experiment produced a net gain of megajoules, the relatively inefficient laser in total pulled some 400 megajoules from the grid for the shot. This means the NIF’s experiment would need to be a hundred times more efficient to totally cover its cost.
These massive lasers would also have to be fired repeatedly for these inertial confinement-type reactors to be a viable energy source. Right now, the lasers take hours to cool down, making some kind of laser-bombarding power plant (while totally awesome-sounding) completely impossible. Wade thinks a future “inertial containment” reactor could work similar to a car engine, producing several miniature explosions per second. Next steps, according to Wade, are to sustain these reactions for tens of seconds or even hundreds of seconds. The goal of ITER, for example, is to continuously sustain a fusion reaction for at least 400 seconds.
“For the last 20 years, we’ve primarily been a science program trying to figure out how to develop those capabilities,” Wade says. “Going forward, I think we will be taking that science and applying it to this energy mission.”
The NIF, along with its tokamak counterparts, are billion-dollar experiments designed to push the very limits of physics (as well as safely test nuclear weapons technology). Although this fusion experiment isn’t a direct path to free, unlimited energy, it is a big and necessary step. Just how the discovery of electricity led to a technological revolution, so too could this humble experiment one day lead to bottling the stars and powering our world.
Setting the record straight on how these two similar sounding energy sources truly differ.
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Clean and sustainable nuclear energy may sound like a washed up, post-war dream, but the modern reality of this power source is much more complicated. For one, nuclear energy in the coming decades will include not only nuclear fission—the type of reaction already driving nuclear power plants—but also the much more elusive nuclear fusion.
If scientists can solve the remaining puzzle pieces behind these technologies, both nuclear fission and fusion are poised to have a big impact on the world’s energy reserves and green energy efforts in the coming decades. But before they do, let’s set the record straight on how these two similar sounding energy sources truly differ
Nuclear Fission
When you’re thinking about nuclear power, odds are you’re probably picturing a process called nuclear fission. To create nuclear fission, atoms of radioactive elements like Uranium are broken apart with neutrons to release an enormous amount of energy. Inside nuclear reactors, this energy is used to create steam, which in turn powers a turbine to produce electricity.
Nuclear Fusion
Unlike its sibling, nuclear fusion has largely been restricted to the realm of science fiction until recently. Instead of breaking something apart, nuclear fusion happens when light atoms are smashed together to create a heavier atom (e.g. two hydrogen atoms combining to form one helium atom). This interaction creates a huge burst of energy that is still burning at the heart of stars all across the universe.
Unlike fission, nuclear fusion also has the added benefit of being self-sustaining without creating harmful waste. However, achieving and controlling fusion has been a lot more difficult for scientists to crack than fission.
One problem facing fusion technology is that in order to create self-sustaining power (a point called “fusion ignition”) it needs to be sparked by a massive amount of energy. In theory, after this initial power push the fusion reactor should then be able to create and sustain even more power than was initially fed into it. However, actually achieving this is easier said than done.
That said, labs like the U.S.’s National Ignition Facility (NIF) and France’s International Thermonuclear Experimental Reactor (ITER) have made progress in recent years with NIF reporting last summer that their reactor was able to generate up to 70 percent of its input energy. Start-ups like Helion Energy are also working toward this goal using magnetic coils to compression the reactor core.
Scientists have claimed to be on the brink of cracking nuclear fusion for decades, but hopefully with any luck that promise may finally be coming true.
We’re one step further down the path to limitless clean power.
On December 5, 2022, the National Ignition Facility in the U.S. achieved ignition by creating more energy via nuclear fusion than they originally put in.
Now, a series of details focuses on how that achievement came to be, and also highlights three subsequent ignition reactions—one of which produced almost double the amount of energy it used.
Investments in renewable energy could be vital to combating the climate crisis in the present day.
Although still a far-future technology, nuclear fusion is really hot right now, both literally and figuratively. Squishing together two light nuclei requires immensely hot temperatures (like, 100 million°C hot), and the fusion industry is similarly sizzling. More than 40 fusion companies now exist around the world—25 of which are in the U.S. alone.
One of the big drivers behind the immense excitement surrounding this futuristic energy-making venture is the fact that Lawrence Livermore National Laboratory’s (LLNL) National Ignition Facility (NIF) achieved “ignition” in December of 2022. This means that for the first time ever, scientists were able to create a fusion reaction that produced more energy than was used to create the reaction in the first place.
Yesterday, LLNL published a series of papers that go into detail about how exactly this major achievement took place and also talk about three other ignition moments that occurred throughout 2023—one of which produced almost twice as much energy as was initially put in.
“A fundamental obstacle to realizing a fusion energy source,” the researchers said in a press release, “has been the ability to control and heat a plasma (a mixture of ions and free electrons) to the conditions required for ignition and to confine the plasma at these conditions over long enough time scales such that more fusion energy is produced than was supplied to initiate the reaction.”
To put it very simply, nuclear fusion is like nuclear fission but in reverse. A fission reactor—the only kind of nuclear reactor used as an energy source today—splits Uranium-235 into two smaller atoms, specifically, barium and krypton. This releases energy that then creates steam and powers turbines. Fusion, on the other hand, happens on the other end of the nuclear binding energy curve. It uses two light nuclei, usually hydrogen isotopes deuterium and tritium, that then overcome the strong nuclear force and a subatomic quirk known as “quantum tunneling.” The resulting fusion creates a helium atom and most importantly energy thanks to that whole “e=mc2” thing.
Although there are many ways to achieve fusion (the Sun is pretty good at it, thanks to its immense gravity), the NIF uses a process known as inertial confinement. In using this method, 192 lasers converge on a hohlraum capsule that creates an X-ray bath. This squeezes the isotopes inside, which collapse at roughly 250 miles per hour, fuse, and release energy. Because the fusion reaction occurs before the fuel disassembles, the plasma is contained by its own inertia (hence the name).
On December 5, 2022, NIF produced 3.15 megajoules (MJ) despite only putting in 2.05 MJ (although this doesn’t account for the energy needed to run the entire facility, which is roughly 100 times greater than the energy that eventually reaches the capsule). Ignition—achieved.
In early August, the NIF announced that their second ignition successfully achieved higher yields than their historic first. While details were scant at the time, the paper reveals that 2.05 MJ of laser energy created 3.88 MJ, which is even higher than the two subsequent ignitions in 2023. However, these efficiencies are happening at a facility that wasn’t exactly designed to maximize output in the first place. Instead, achieving ignition in order to keep the U.S.’s nuclear deterrence safe and reliable is its primary goal.
“The NIF laser architecture and target configuration was chosen to give the highest probability for fusion ignition for research purposes and was not optimized to produce net energy for fusion energy applications,” the NIF said. “Inertial fusion energy applications requiring advancements to the underlying scheme require further development, such as laser energy usage, shot rate, target robustness, higher fuel compression levels, and cost.”
The fusion era is finally upon us. Laboratories regularly achieve ignition, international projects gear up for “first plasma” on groundbreaking experiments, and companies continue to invest in the energy source of the future—but not the energy source of the present.
While fusion energy is certainly exciting, it’s arriving too late to solve the current climate crisis. Research into this emerging field continues to grow, and as it does, so too must investments in the renewable energy technologies of today if we ever want to see a world powered by the physics of our own Sun.
Nuclear fusion is the process that powers the Sun and all other stars. During fusion, the nuclei of two atoms are brought close enough together that they fuse together, releasing huge amounts of energy.
Replicating this process on Earth has the potential to deliver almost limitless electricity with virtually zero carbon emissions and greater safety, and without the same level of nuclear waste as fission.
But building what is essentially a mini star on Earth and holding it together inside a reactor is not an easy task. It requires immense temperatures and pressures and extremely strong magnetic fields.
Right now we don’t quite have materials capable of withstanding these extremes. But researchers like me are working to develop them, and we’ve found some exciting things along the way.
Tokamaks
There are many ways to contain nuclear fusion reactions on Earth, but the most common uses a doughnut shaped device called a tokamak. Inside the tokamak, the fuels for the reaction – isotopes of hydrogen called deuterium and tritium – are heated until they become a plasma. A plasma is when the electrons in the atoms have enough energy to escape the nuclei and start to float around. Because it’s made up of electrically charged particles, unlike a normal gas, it can be contained in a magnetic field. This means it doesn’t touch the reactor sides – instead, it floats in the middle in a doughnut shape.
When deuterium and tritium have enough energy they fuse together, creating helium, neutrons and releasing energy. The plasma has to reach temperatures of 100 million degrees Celsius for large amounts of fusion to happen – ten times hotter than the centre of the Sun. It has to be much hotter because the Sun has a much higher density of particles.
Although it’s mostly contained within a magnetic field, the reactor still has to withstand huge temperatures. At Iter, the world’s biggest fusion experiment, expected to be built by 2035, the hottest part of the machine would reach around 1,300℃.
Deuterium tritium fusion.
While the plasma will mostly be contained in a magnetic field, there are times when the plasma might collide with the walls of the reactor. This can result in erosion, fuel being implanted in the walls and modifications to the material properties.
On top of the extreme temperatures, we also have to consider the by-products of the fusion reaction of deuterium and tritium, like extremely high energy neutrons. Neutrons have no charge so can’t be contained by the magnetic field. This means they hit against the walls of the reactor, causing damage.
The breakthroughs
All these incredibly complex challenges have contributed to huge advances in materials over the years. One of the most notable has been high temperature superconducting magnets, which are being used by various different fusion projects. These behave as superconductors at temperatures below the boiling point of liquid nitrogen. While this sounds cold, it’s high compared to the much colder temperatures other superconductors need.
In fusion, these magnets are only metres away from the high temperatures inside the tokamak, creating an enormously large temperature gradient. These magnets have the potential to generate much stronger magnetic fields than conventional superconductors, which can dramatically reduce the size of a fusion reactor and may speed up the development of commercial fusion.
We do have some materials designed to cope with the various challenges we throw at them in a fusion reactor. The front-runners at the moment are reduced activation steels, which have an altered composition to traditional steels so the levels of activation from neutron damage is reduced, and tungsten.
One of the coolest things in science is something initially seen as a potential issue can turn into something positive. Fusion is no exception to this, and one very niche but noteworthy example is the case of tungsten fuzz. Fuzz is a nanostructure that forms on tungsten when exposed to helium plasma during fusion experiments. Initially considered a potential issue due to fears of erosion, there’s now research into non fusion applications, including solar water splitting – breaking it down into hydrogen and oxygen.
However, no material is perfect, and there are several remaining issues. These include the manufacture of reduced activation materials at a large scale and the intrinsic brittleness of tungsten, which makes it a challenge to work with. We need to improve and refine on the existing materials we have.
The challenges
Despite the huge advances in the field of materials for fusion, there’s still a lot of work that needs to be done. The main issue is we rely on several proxy experiments to recreate potential reactor conditions, and have to try and stitch this data together, often using very small samples. Detailed modelling work helps to extrapolate predictions of material performance. It would be much better if we could test our materials in real situations.
The pandemic has had a major impact on materials research because it’s been more difficult to carry out real life experiments. It’s really important that we continue to develop and use advanced models to predict material performance. This can be combined with advances in machine learning, to identify the key experiments we need to focus on and identify the best materials for the job in future reactors.
The manufacturing of new materials has typically been in small batches, focusing only on producing enough materials for experiments. Going forward, more companies will continue to work on fusion and there will be more programmes working on experimental reactors or prototypes.
Because of this, we are getting to the stage where we need to think more about industrialisation and development of supply chains. As we edge closer to prototype reactors and hopefully power plants in the future, developing robust large scale supply chains will be a huge challenge.
Containing this ultra-hot type of matter is key to unlocking nuclear fusion, so it’s a big step forward in our attempts to make this clean, safe, and virtually limitless source of energy something we can rely on.
Unlike nuclear fission, which our existing nuclear power plants achieve by splitting atoms, nuclear fusion involves fusing atoms together at incredibly high temperatures – the same reaction that powers our Sun.
If we can manage to control the reaction safely and sustainably it would be huge, because nuclear fusion can generate power for thousands of years using little more than salt water, and without putting out nuclear waste. And the Korean reactor just took us a step closer to that.
The KSTAR reactor is housed at the National Fusion Research Institute (NFRI) and is a tokamak-type reactor, where plasma blobs reaching temperatures of up to 300 million degrees Celsius (about 540 million degrees Fahrenheit) are held in place by super-powerful magnetic fields.
If the blobs can be contained for long enough, hydrogen atoms can fuse together to create heavier helium atoms, releasing energy – a similar process is happening on the Sun, which is why reactors are sometimes described as trying to put “a star in a jar”.
And while the reactors of today take up much more energy than they produce, each time a record like this is broken, scientists get closer to their ultimate goal.
“This is a huge step forward for [the] realisation of the fusion reactor,” the NFRI said in a statement, World Nuclear News reports.
There are plenty of variables scientists can alter to tweak nuclear fusion reactions and different ways they can be measured: from pressure to temperature to time.
At the same time, the researchers at the NFRI have also developed a new plasma “operation mode” that they hope will enable reactions to handle greater pressures at lower temperatures in the future.
And getting the whole process more efficient is important if we’re to get nuclear fusion working at the right scale.
If scientists can crack the “star in a jar” problem, we’d have a nuclear energy source that’s far safer than the nuclear fission plants we rely on now, because no radioactive waste is produced and there’s no chance of a plant meltdown.
We should note that the results haven’t been published in a journal or independently verified yet, so we’ll have to wait for confirmation that 70 seconds really is the new benchmark to hit for this high-performance plasma.
But as the KSTAR reactor continues to push the boundaries of what’s possible, it should help bring scientists closer and closer to figuring out how to harness the potential of nuclear fusion.
As NFRI president Keeman Kim puts it: “We will exert efforts for KSTAR to continuously produce world-class results, and to promote international joint research among nuclear fusion researchers.”
One of the biggest challenges in the fusion energy development is finding the best shape for the device to contain the plasma, but physicists in the United States believe they may have found a new kind of nuclear fusion device that could be the most commercially viable design yet.
HOLY GRAIL
Physicists around the world are on a mad dash to build a nuclear fusion machine that can replicate the Sun’s atom-fusing process and provide everyone with a low-cost, sustainable energy resource—effectively ending our dependence on fossil fuels.
Replicating how the sun and stars create energy through fusion is essentially like putting “a star in a jar,” although there is no “jar” in existence that is not only capable of containing superhot plasma, but also low-cost enough that it can be built around the world—although it’s not for lack of trying.
In fact, physicists are working on a new kind of nuclear fusion device that could be the most commercially viable design yet.
In a new paper published in Nuclear Fusion, physicists working at the U.S. Department of Energy’s Princeton Plasma Physics Laboratory (PPPL) assert that a model for such fusion device “already exists in experimental form – the compact spherical tokamaks at PPPL and Culham, England.”
Test cell of the National Spherical Torus Experiment-Upgrade with tokamak in the center.
SPHERICAL TOKAMAKS
Current designs for this so-called “jar” essentially call for doughnut shaped objects that come complete with powerful magnetic fields which suspend the plasma inside it, called tokamaks. It’s incredibly expensive to make and also hard to maintain, which is why physicists continue to develop new designs that will, hopefully, keep the cost down.
So far, there are two advanced spherical tokamaks in various stages of development. The first is the Mega Ampere Spherical Tokamak (MAST), which UK expects to be completed soon; the other is the National Spherical Torus Experiment Upgrade (NSTX-U) at PPPL, which went online last year.
“We are opening up new options for future plants,” said Jonathan Menard, lead author and program director for the NSTX-U.
But the devices, described in the 43-page paper, still have a long way to go. They must first be able to control the turbulence created after the plasma particles are subjected to electromagnetic fields, and also control how the superhot plasma particles interact with the device’s walls to avoid possible disruptions, which can happen if the plasma becomes too impure.
PPPL Director Stewart Prager said these two reactors, “will push the physics frontier, expand our knowledge of high temperature plasmas, and, if successful, lay the scientific foundation for fusion development paths based on more compact designs.”
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