MIT announces major breakthrough in nuclear fusion with its ‘one-of-a-kind’ superconducting magnet

A source ofenergy practical, inexpensive and what’s more, zero carbon. Today more than ever, everyone dreams of it. Researchers have long worked to make this dream come true. In particular, they placed their hopes in the nuclear fusion. For Maria Zuber, vice-president for research at Massachusetts Institute of Technology (MIT, United States), “Nuclear fusion – the one used by our Sun to shine — is even, in many ways, the clean energy source par excellence. The amount of energy it would make available from an almost unlimited resource – understand water – would really be a game-changer “. The only downside: we still have to find a way to tame this energy.

While on the Bouches-du-Rhône side, the first of six pieces of a gigantic electromagnet has just been delivered to the site of Iter site – a facility intended to demonstrate that nuclear fusion can become the source of clean energy – it may well be that a “A turning point has been taken in the science and technology of nuclear fusion” thanks to Commonwealth Fusion Systems and you Massachusetts Institute of Technology (MIT, United States). Leaning on an electromagnet superconductor at high temperature, they managed to produce a magnetic field of 20 teslas. The most intense magnetic fields ever created on Earth using such a device. This is about four times more than what is advertised for Iter. And that was precisely what researchers lacked to hope to succeed in confining a plasma to the heart of a donut-shaped device – the physicists talk about tokamak – which would then produce, by nuclear fusion, more energy than it consumes.

Before continuing, perhaps it is worth remembering that the very principle of nuclear fusion by magnetic confinement is there. The first step is to heat a gas to form a plasma. For this, it is still necessary to reach more than 100 million degrees Celsius. Because it is then that the deuterium and the tritium – isotopes of the’hydrogen -, introduced in the tokamak, begin to merge. By emitting nuclei ofhelium and neutrons. And it is the energy of these neutrons, transferred in the form of heat to a liquid coolant which circulates in the walls of the tokamak, which will make it possible to produce electricity. In order to maintain the plasma – and therefore the nuclear fusion reactions – it is necessary, on the other hand, to prevent it from coming into direct contact with the walls in question. We must therefore succeed in confining it. Thanks to a magnetic field.

Thanks to a high temperature superconducting magnet

Until then, most tokamaks relied on conventional electromagnets, in copper. The Iter project, on the other hand, relies on low-temperature superconductors – temperatures close to absolute zero, of the order of -270 ° C. And MIT’s work focuses on high-temperature superconductors – which still operate at around -250 ° C. Physicists call them Rebco – for rare-earth barium copper oxide. “We have built a magnet one of a kind “, explains Joy Dunn, operations manager at Commonwealth Fusion Systems, in a MIT press release. The result of three years of work on a magnet arranged in the shape of a flat ribbon. A magnet ultimately made up of 16 stacked plates, each of which alone would constitute the most powerful high-temperature superconducting magnet in the world.

This magnet was really the element that physicists lacked to finally build a system capable of producing energy by nuclear fusion. With, what is more, performances equal to that of a superconductor at low temperature, but in a system … 40 times smaller! The base physique such a device had been asked last year in a series of articles. Its viability had been confirmed by simulation. And now that this magnet exists in the real world, all that remains is to build a demonstrator.

The researchers named it Sparc. It should be able to be put into service from 2025. To test, on a small scale and only a few seconds at a time, the feasibility of a Power plant fusion that engineers are considering by 2033. Objective: to generate 50-100 MW of thermal power by counting on a magnetic field of 12 Tesla, but above all, with a gain of 2 – the device should generate twice the energy required to make it work – knowing that the current record is … 0.7!

“There are still many challenges to overcome, not the least of which is to develop a design that allows reliable and durable operation”, emphasizes Maria Zuber. To produce electricity on an industrial scale, it will indeed be necessary to successfully operate a tokamak continuously, even when the conditions at its heart are dire. “And knowing that the goal here is commercialization, another major challenge will be economic. “ Thus, nuclear fusion is unlikely to play a significant part in the production of electricity for several decades to come. “But this moment that we have just lived is a bit like the ‘wow’ moment. The one from which I start to think that we can really make it happen ”, concludes Maria Zuber.

Nuclear fusion: new superconductors would change the game

Hope for an almost inexhaustible energy, nuclear fusion is based on technologies still in development. Progress could accelerate, says a team from MIT launched in a project dubbed ARC. The key: a new generation of superconductors that can create much more intense magnetic fields, which would simplify the design of a reactor.

Article by Nathalie Mayer published on 08/10/2015

For several decades, scientists have dreamed of exploiting the nuclear fusion, this phenomenon that takes place at the heart of stars, to produce safe, almost inexhaustible and almost clean energy. Thanks to recent advances in the field of magnetic technologies, American researchers from the WITH (Massachusetts Institute of Technology) estimate that it is possible to build a compact nuclear fusion reactor in just ten years or so.

To achieve their ends, they employed new superconductors, already commercially available. These superconductors based on barium oxide, copper and rare earth, and baptized Rebco (rare-earth barium copper oxide), come in the form of ribbons. Enough to allow MIT researchers to manufacture coils generating magnetic fields particularly intense, enough to confine plasma, the key to a nuclear fusion reactor. They named their project ARC, to affordable, robust, compact (affordable, robust and compact). We can not fail to see a winkeye to the energy source of the‘Iron Man armor, the hero of the Marvel Comics and the eponymous films.

To better understand, let’s go back to the physical basics of nuclear fusion. It consists in fusing two light atomic nuclei, in this case hydrogen nuclei. However, the nuclei are electrically positive and two charges of the same sign have the annoying tendency to repel each other. Only extreme temperatures, which would be counted in millions of degrees, can accelerate nuclei to the point of allowing them to break the barrier erected by electromagnetic forces. And, currently most scientists agree that the best solution to achieve this is that of the tokamak, a kind of magnetic box in which two isotopes of hydrogen, the deuterium and the tritium, would be confined and maintained at a temperature of some 150 million degrees. At this temperature, the matter comes in the form of plasma, an extremely hot and electrically charged gas. An environment favorable to nuclear fusion.

Like Iter but better

A large-scale prototype of this type of reactor is currently under development. construction in Saint-Paul-lez-Durance, in Provence-Alpes-Côte d’Azur. The project Iter aims to validate the scientific and technological feasibility of fusion energy and to pave the way for its industrial exploitation. At the heart of this reactor will be produced helium nuclei, neutrons and energy. The helium nuclei, charged, will remain confined in the tokamak under the effect of the magnetic field. 80% of the energy produced will be carried by neutrons, insensitive to the magnetic field. These will transfer their energy in the form of heat to the walls of the reactor. A heat that will then be used to produce steam and electricity.

The solution proposed by MIT researchers for this ARC project is based on the same physical principles. However, based on much more intense magnetic fields, it makes it possible to reduce the size of the reactor and, therefore, its cost. It also makes it possible to consider other advances. Scientists have indeed established that by doubling the intensity of the applied magnetic field, the energy produced could be multiplied … by 16! With a reactor such as this ARC, the energy produced would be 10 times greater than that expected using conventional superconductors. Thus, a reactor with a diameter two times smaller than that of Iter could produce just as much energy, at a much lower cost and duration shorter in construction, explains the MIT press release. Remember, however, that Iter is not intended to produce electricity but to validate technical concepts.

Among the other advantages cited by the American team: the possibility of replacing the fusion core without having to dismantle the entire reactor. Enough to easily conduct further research (materials, design, etc.) in order to further improve the performance of the system. Likewise, the materials solid which usually surround this type of reactor could be replaced by a liquid which can easily be circulated around the melting chamber and replaced without great expense.

So far, no fusion reactor has been able to produce more energy than it consumes. However, in its current configuration, ARC would theoretically be able to produce three times more electricity than that used to make it work. And MIT researchers assure that this yield could be further doubled …