Nuclear fusion hit a milestone thanks to better reactor walls – this engineering advance is building toward reactors of the future.
Scientists in England have set a new record for the quantity of energy generated during a controlled, sustained fusion reaction. The creation of 59 megajoules of energy over five seconds at the Joint European Torus – or JET – experiment in England has been dubbed a “breakthrough” by certain media organizations and has sparked physicists’ interest. However, a frequent saying about fusion energy generation is that it is “always 20 years away.”
We are a nuclear physicist and a nuclear engineer working to develop controlled nuclear fusion for power generation.
The JET finding represents significant progress in the understanding of fusion physics. But, perhaps more crucially, it demonstrates that the new materials used to create the fusion reactor’s inner walls performed as expected. The fact that the new wall structure functioned so well sets these findings apart from past milestones and brings magnetic fusion closer to reality.
Fusing particles together
Nuclear fusion is the merging of two atomic nuclei into one compound nucleus. This nucleus then breaks apart and releases energy in the form of new atoms and particles that speed away from the reaction. A fusion power plant would capture the escaping particles and use their energy to generate electricity.
There are a few different ways to safely control fusion on Earth. Our research focuses on the approach taken by JET – using powerful magnetic fields to confine atoms until they are heated to a high enough temperature for them to fuse.
The fuel for current and future reactors are two different isotopes of hydrogen – meaning they have the one proton, but different numbers of neutrons – called deuterium and tritium. Normal hydrogen has one proton and no neutrons in its nucleus. Deuterium has one proton and one neutron while tritium has one proton and two neutrons.
For a fusion reaction to be successful, the fuel atoms must first become so hot that the electrons break free from the nuclei. This creates plasma – a collection of positive ions and electrons. You then need to keep heating that plasma until it reaches a temperature over 200 million degrees Fahrenheit (100 million Celsius). This plasma must then be kept in a confined space at high densities for a long enough period of time for the fuel atoms to collide into each other and fuse together.
To control fusion on Earth, researchers developed donut-shaped devices – called tokamaks – which use magnetic fields to contain the plasma. Magnetic field lines wrapping around the inside of the donut act like train tracks that the ions and electrons follow. By injecting energy into the plasma and heating it up, it is possible to accelerate the fuel particles to such high speeds that when they collide, instead of bouncing off each other, the fuel nuclei fuse together. When this happens, they release energy, primarily in the form of fast-moving neutrons.
During the fusion process, fuel particles gradually drift away from the hot, dense core and eventually collide with the inner wall of the fusion vessel. To prevent the walls from degrading due to these collisions – which in turn also contaminates the fusion fuel – reactors are built so that they channel the wayward particles toward a heavily armored chamber called the divertor. This pumps out the diverted particles and removes any excess heat to protect the tokamak.
The walls are important
A major limitation of past reactors has been the fact that divertors can’t survive the constant particle bombardment for more than a few seconds. To make fusion power work commercially, engineers need to build a tokamak vessel that will survive for years of use under the conditions necessary for fusion.
The divertor wall is the first consideration. Though the fuel particles are much cooler when they reach the divertor, they still have enough energy to knock atoms loose from the wall material of the divertor when they collide with it. Previously, JET’s divertor had a wall made of graphite, but graphite absorbs and traps too much of the fuel for practical use.
Around 2011, engineers at JET upgraded the divertor and inner vessel walls to tungsten. Tungsten was chosen in part because it has the highest melting point of any metal – an extremely important trait when the divertor is likely to experience heat loads nearly 10 times higher than the nose cone of a space shuttle reentering the Earth’s atmosphere. The inner vessel wall of the tokamak was upgraded from graphite to beryllium. Beryllium has excellent thermal and mechanical properties for a fusion reactor – it absorbs less fuel than graphite but can still withstand the high temperatures.
The energy JET produced was what made the headlines, but we’d argue it is in fact the use of the new wall materials which make the experiment truly impressive because future devices will need these more robust walls to operate at high power for even longer periods of time. JET is a successful proof of concept for how to build the next generation of fusion reactors.
The next fusion reactors
The JET tokamak is the largest and most advanced magnetic fusion reactor currently operating. But the next generation of reactors is already in the works, most notably the ITER experiment, set to begin operations in 2027. ITER – which is Latin for “the way” – is under construction in France and funded and directed by an international organization that includes the U.S.
ITER is going to put to use many of the material advances JET showed to be viable. But there are also some key differences. First, ITER is massive. The fusion chamber is 37 feet (11.4 meters) tall and 63 feet (19.4 meters) around – more than eight times larger than JET. In addition, ITER will utilize superconducting magnets capable of producing stronger magnetic fields for longer periods of time compared to JET’s magnets. With these upgrades, ITER is expected to smash JET’s fusion records – both for energy output and how long the reaction will run.
ITER is also expected to do something central to the idea of a fusion powerplant: produce more energy than it takes to heat the fuel. Models predict that ITER will produce around 500 megawatts of power continuously for 400 seconds while only consuming 50 MW of energy to heat the fuel. This mean the reactor produced 10 times more energy than it consumed – a huge improvement over JET, which required roughly three times more energy to heat the fuel than it produced for its recent 59 megajoule record.
JET’s recent record has shown that years of research in plasma physics and materials science have paid off and brought scientists to the doorstep of harnessing fusion for power generation. ITER will provide an enormous leap forward toward the goal of industrial scale fusion power plants.
- David Donovan – Associate Professor of Nuclear Engineering, University of Tennessee
- Livia Casali – Assistant Professor of Nuclear Engineering, Zinkle Faculty Fellow, University of Tennessee
This article was first published in The Conversation.
fusion as presented is going to be a lot messier than previously thought…..if it ever makes it to commercial operations……
Oh man, this kid is five periods serious!
The emperor has no clothes deal about fusion is the energy conversion of crazy hot neutrons and helium nuclei into the regular electricity we all love and know. Not ever gonna be limitless or clean. They’re still working out how to contain the hot neutron plasma without destroy the material container for it? Where do we get to the boiling water to generate steam without irradiating the eater and pipes containg the eater? These guys are all charlatans.
Once again an article dedicated to misleading the public. The amount of energy put into the plasma is much smaller than the amount of energy used. Breakeven in a reaction is meaningless when it still end up in a deficit with no net energy created.
Where or how will they store 500 megawatts produced in 400 seconds?
I assume that they will use it to fry the chicken for the three day rave that will follow celebrating the feat.
Important-error made in in first graphic diagram underline description
describes a final components as “helium and free electron”.
There reaction results should have been “helium and a free high energy neutron”.
Their vs there
I agree, their diagram if correct, shows a free neutron. And they are associate and assistant professors. No check reading for corrections.
I be thinking great idea, fusion. Talk has been a round …. energy used to power storage batteries ,example 😊👽🛸
Nobody seems to realize that the Sun doesn’t get to choose what kind of hydrogen it has used for 5 billion years. It is using what it got and, I hate to say it but, it is not fusion at the core of the sun.
The energy that scientists seek is called quark plasma and it is what black holes are made of. Fusion is simply a method of turning kinetic energy into potential energy. That is why it always takes more energy to create it than what comes out. That fact will never change.
Quark plasma uses the strong force between quarks and the dark matter of space to exist. Dark matter is made of extremely pressurized electron neutrinos. Once the quarks have been separated from a sufficient enough reaction, it is the pressure and density of dark matter that keeps the quarks apart indefinitely. As the dark matter comes into the reaction to disrupt the quarks, the strong force throws the neutrinos out as the most powerful radiation in the universe which are gamma rays. That’s where all the cosmic and gamma rays come from that scientists can’t explain because they think nothing can escape a black hole. A mass of quark plasma creates all the naturally occurring elements all by itself. First, the quarks and electron neutrinos fuse on the surface to create the first neutrons the black hole will ever possess. This turns the mass into a neutron star but the neutrons are only on the surface. The neutrons break down into the first hydrogen the mass will see. Then, the constantly forming neutrons fuse with the hydrogen to form the first helium using the beta minus decay reaction. That is where fusion happens, not at the core. It is nothing but a conservation of energy and mass. The mass continues creating heavier elements making the star darker until the light goes out and a surface forms. That is when the atmosphere forms because the surface is now safe from the quark plasma underneath.
This is why scientists found helium leaking from the Earth that they couldn’t explain. This is why the Kola superdeep borehole had “boiling hydrogen” leaking from the hole that could not be explained. These elements live right outside the quark plasma core.
Unfortunately, the big bang theory is making science positive that fusion works because this theory only gives science already formed elements to work with. It is very obvious that fusion is not the energy that has made our Sun so powerful for 5 billion years. Scientists create fusion all the time but it should result in a run-away process like the sun is exhibiting. It is quark plasma that will provide this run-away reaction by using the limitless energy of the dark matter of space as a catalyst that our planet uses to create gravity.
A quark plasma reactor will be incredibly easy to build. It will be a thick, hollow sphere with a small portion of pure hydrogen, with no neutrons, in a vacuum. The hydrogen will be compromised by heating it and then it will be shocked into existence will a massive shot of electricity. Once the reaction is started, nothing will be required from us to keep it going except to harvest the energy. The gamma rays will heat the walls and the energy will be gathered from the outer parts of the sphere. The amount of energy a small amount of hydrogen will create will be incredible.
Mike Pollack, that explains a lot, glad you solved the problem of how the Universe works. Now we just have to build the power plant!
This process creates an enormous amount of heat. Where is all of this hea going, increasing our current temperatures?
Heat is the purpose, I think – to be converted into electricity.
Every comment here is negative. So much negative energy could reduce steam to ice.
Won’t tungsten absorb more neutrons than graphite and thus produce more radioactivity (which is a bad thing for a fusion reactor to do)?
Well I suppose this process would be viable for powering space craft..no problem with overheating space.
When I was a kid fusion was “50 years away and always will be.” Then the naysayers updated it to 30 years and that was the refrain until a few years ago. Now it’s 20 years? When the first commercial reactor is getting ready to go online these idiots will say “fusion is a week away and always will be!” Moving the goalpost to 30 years bugged me but most journalists probably weren’t paying attention decades ago. But I’ve seen the 30 year line still being repeated in the last year. There is no excuse at all for treating the new 20-year version as having a shred of credibility.
Jeff, the Big Bang theory erroneously makes scientists think fusion is the answer to all our problems. The only thing is, it isn’t. Fusion is part of kinetic energy turning into potential energy. It is impossible for it to create energy. Obviously, the proof of my statement has been proven for “50 years”.
Excellent thoughts and clear sense can be realized in progress..in time. My best projects were guided by “Keep It Simple Stupid”. anything else is for vanity or control or need more money. Excess green grid pumping flood water over the rockys for food production, or raising a stupid weight with wave wind or tidal power has more than enough energy at usable cost and jobs for the masses to maintain. Obviously its always 10 20 30 years away to support the very few who can think at these levels of science and engineering and hence progress. It must be balanced and practical. Create a sun – really? And the energy would be cheap – right? Darn another brown out in texas..cough. Great article/comments TY.