El ITER,12 (International Thermonuclear Experimental Reactor, en español Reactor Termonuclear Experimental Internacional), es un experimento científico a gran escala que intenta producir un plasma de fusión que tenga diez veces más potencia térmica que la potencia necesaria para calentar el plasma. Como sistema de reactor, el ITER será equivalente a un reactor de potencia cero (neto).3 Los participantes en el diseño conceptual de actividades del ITER eligieron esta palabra para expresar sus esperanzas comunes en que el proyecto podría conducir al desarrollo de una nueva forma de energía. Es un proyecto de gran complejidad ideado en 1986 en la Unión Soviética (Tokamak), para demostrar la factibilidad científica y tecnológica de la fusión nuclear. El ITER se está construyendo en Cadarache (Francia) y costará 24 000 millones de euros aproximadamente, convirtiéndolo en el quinto proyecto más costoso de la historia, después del Programa Apolo, de la Estación Espacial Internacional, del Proyecto Manhattan y del desarrollo del sistema GPS.4ITER, además, significa El camino en latín, y este doble sentido refleja el rol del ITER en el perfeccionamiento de la fusión nuclear como una fuente de energía para usos pacíficos e innovadores.
Su objetivo es probar todos los elementos necesarios para la construcción y funcionamiento de un reactor de fusión nuclear que serviría de demostración comercial, además de reunir los recursos tecnológicos y científicos de los programas de investigación desarrollados en ese entonces por la Unión Soviética, los Estados Unidos, la Unión Europea (a través de EURATOM) y Japón. El ITER cuenta con el auspicio de la IAEA, así como una forma de compartir los gastos del proyecto.
El reactor experimental de fusión nuclear está basado en el diseño soviético, llamado Tokamak. Este es la base de la construcción del modelo de demostración comercial.
El ITER está diseñado para calentar un plasma de hidrógeno gaseoso hasta 100 millones de grados Celsius. El ITER debería generar su primer plasma en diciembre de 2025.6
ITER se basa en el concepto de "tokamak" de confinamiento magnético, en la que se contiene el plasma en una cámara de vacío con forma toroidal. El combustible —una mezcla de deuterio y tritio, dos isótopos del hidrógeno— se calienta a temperaturas superiores a los 150 millones °C, formando un plasma caliente. Los fuertes campos magnéticos se utilizan para mantener el plasma lejos de las paredes, los cuales son producidos por bobinas superconductoras que rodean al contenedor, y por una corriente eléctrica impulsada a través del plasma. El problema reside en la enorme dificultad de comprimir el hidrógeno de un modo uniforme. En las estrellas la gravedad comprime el hidrógeno en una esfera perfecta de modo que el gas se calienta uniforme y limpiamente. En las condiciones del diseño del reactor esta uniformidad es muy difícil de alcanzar.
El 21 de mayo de 2000 se anuncia que físicos estadounidenses han superado uno de los problemas de la fusión nuclear en dispositivos de tipo Tokamak, el fenómeno llamado modos localizados en el borde, o ELMs (por sus siglas en inglés). Los ELM provocarían una erosión de las protecciones interiores de la cámara de vacío del reactor, obligando a su reemplazo frecuente.
En un artículo publicado el domingo 21 de mayo de 2000 en la revista británica Nature Physics, un equipo dirigido por Todd Evans de la empresa General Atomics, California, anuncia que descubrieron que un pequeño campo magnético resonante, proveniente de las bobinas especiales ubicadas en el interior de la vasija del reactor, crea una interferencia magnética “caótica” en el borde del plasma que detiene la formación de flujos.
El 24 de mayo de 2006 los siete socios del proyecto ITER --Unión Europea, Japón, Estados Unidos, Corea del Sur, India, Rusia y China-- firmaron en Bruselas el acuerdo internacional para el lanzamiento del reactor de fusión internacional con el modelo Tokamak, que se construirá en Cadarache, en el Sudeste de Francia usando el diseño Tokamak. Los costes de construcción del reactor se estimaron en 4.570 millones de euros y la duración de la construcción en 10 años. La UE y Francia se comprometieron a contribuir con el 45 % del coste, mientras que las otras seis partes acordaron aportar cada una el 9%.
Durante el Consejo de Gobierno del proyecto ITER que tuvo lugar en noviembre de 2016 se aprobó la nueva planificación global del proyecto, conteniendo como principales hitos el Primer Plasma en 2025 y las primeras operaciones con deuterio y tritio para el 2035.7
Durante el proceso para definir emplazamiento del centro de investigación y del futuro reactor de fusión se presentaron varios inconvenientes. Durante el mes de noviembre existe una pugna entre Francia y España por la obtención de la candidatura de la UE para situar el ITER. La opción española tras descartar algunas fue Vandellós. En diciembre de 2003 los seis miembros no pudieron decidirse entre situarlo en Francia o en Japón. Al parecer, por motivos políticos los Estados Unidos estuvieron en contra de la candidatura de Francia (se presume que se debió a su negativa a apoyar la invasión de Irak de 2003), lo cual dificultó la decisión definitiva. El 26 de diciembre de 2003, se elige finalmente la candidatura de Cadarache como la opción de la UE.
Se llegó a plantear la posibilidad de que la UE siguiese adelante con el proyecto sin Japón y Estados Unidos. Esto fue sugerido por la Comisión Europea y por Francia, que contaban con que el aporte de estos dos países podría sustituirse con la entrada de nuevos socios y con aumentos de los países de la UE. Se había anunciado que India, Suiza y Brasil estarían dispuestos a participar en el proyecto europeo.
Los sitios candidatos fueron:
Cadarache (Cerca de Marsella), (contaba con el apoyo de la UE, Rusia y China)
Rokkasho (Japón), (contaba con el apoyo de Estados Unidos, Japón y Corea del Sur)
Vandellós (Tarragona, España), (Renunció a favor de Cadarache tras la decisión de la UE de presentar una única candidatura)
El 28 de junio de 2005 en Moscú, se llegó finalmente a un acuerdo sobre la localización del reactor, que fue ubicado en Cadarache.
La UE asumirá el 40% de los costes de construcción, Francia costeará un 10% adicional mientras que los cinco socios restantes sufragarán 10% cada uno.
El recipiente de vacío es la parte central de la máquina ITER: un recipiente de acero de doble pared en el que el plasma está contenido por medio de campos magnéticos.
El recipiente de vacío ITER será dos veces más grande y 16 veces más pesado que cualquier recipiente de fusión fabricado previamente: cada uno de los nueve sectores con forma de toro pesará entre 390 y 430 toneladas. Cuando se incluyen todas las estructuras de blindaje y puertos, esto suma un total de 5,116 toneladas. Su diámetro externo medirá 19.4 metros (64 pies), el interno 6.5 metros (21 pies). Una vez ensamblada, toda la estructura tendrá 11.3 metros (37 pies) de altura.
La función principal del recipiente de vacío es proporcionar un recipiente de plasma sellado herméticamente. Sus componentes principales son el buque principal, las estructuras portuarias y el sistema de soporte. El recipiente principal es una estructura de doble pared con nervaduras de refuerzo poloidales y toroidales entre conchas de 60 milímetros de grosor (2.4 pulgadas) para reforzar la estructura del recipiente. Estas costillas también forman los pasos de flujo para el agua de enfriamiento. El espacio entre las paredes dobles se llenará con estructuras de protección hechas de acero inoxidable. Las superficies internas del buque actuarán como interfaz con los módulos reproductores que contienen el componente de mantilla reproductora. Estos módulos proporcionarán protección contra los neutrones de alta energía producidos por las reacciones de fusión y algunos también se utilizarán para conceptos de mejoramiento de tritio.
ITER producirá energía al fusionar deuterio y tritio en helio.
El recipiente de vacío tiene 18 puertos superiores, 17 ecuatoriales y 9 puertos inferiores que se utilizarán para operaciones de manipulación remota, sistemas de diagnóstico, inyecciones de haz neutro y bombeo de vacío.
ITER ("The Way" in Latin) is one of the most ambitious energy projects in the world today.
In southern France, 35 nations* are collaborating to build the world's largest tokamak, a magnetic fusion device that has been designed to prove the feasibility of fusion as a large-scale and carbon-free source of energy based on the same principle that powers our Sun and stars.
The experimental campaign that will be carried out at ITER is crucial to advancing fusion science and preparing the way for the fusion power plants of tomorrow.
The primary objective of ITER is the investigation and demonstration of burning plasmas—plasmas in which the energy of the helium nuclei produced by the fusion reactions is enough to maintain the temperature of the plasma, thereby reducing or eliminating the need for external heating. ITER will also test the availability and integration of technologies essential for a fusion reactor (such as superconducting magnets, remote maintenance, and systems to exhaust power from the plasma) and the validity of tritium breeding module concepts that would lead in a future reactor to tritium self-sufficiency.
Thousands of engineers and scientists have contributed to the design of ITER since the idea for an international joint experiment in fusion was first launched in 1985. The ITER Members—China, the European Union, India, Japan, Korea, Russia and the United States—are now engaged in a decades-long collaboration to build and operate the ITER experimental device, and together bring fusion to the point where a demonstration fusion reactor can be designed.
We invite you to explore the ITER website for more information on the science of ITER, the ITER international collaboration and the large-scale building project that is underway in Saint Paul-lez-Durance, southern France.
*Update September 2023: The nations participating in ITER include the 27 European Union countries plus China, India, Japan, Korea, the Russian Federation, and the United States. Whereas Switzerland and the United Kingdom (pre-Brexit) had been participating in the ITER Project through Euratom, the status of both nations in relation to Euratom has changed. Switzerland currently has the status of a "non-associated third country" in Euratom while negotiations on an association agreement continue; as such, it is considered by Europe to be a non-participating member in ITER construction. The United Kingdom announced in September 2023 that it will no longer pursue an association agreement with Euratom, but that it will seek to continue and enhance its international partnerships, including with ITER. For the present, the ITER Project is honouring any existing contracts with UK and Swiss citizens and companies, but not concluding new contracts.
WHAT WILL ITER DO?
The amount of fusion energy a tokamak is capable of producing is a direct result of the number of fusion reactions taking place in its core. Scientists know that the larger the vessel, the larger the volume of the plasma ... and therefore the greater the potential for fusion energy.
With six times the plasma volume of the largest machine operating today, the ITER Tokamak will be a unique experimental tool, capable of longer plasmas and better confinement. The machine has been designed specifically to:
1) Achieve a deuterium-tritium plasma in which the fusion conditions are sustained mostly by internal fusion heating Fusion research today is at the threshold of exploring a "burning plasma"—one in which the heat from the fusion reaction is confined within the plasma efficiently enough for the self-heating effect to dominate any other form of heating. Scientists are confident that the plasmas in ITER will not only produce much more fusion energy, but will remain stable for longer periods of time.
2) Generate 500 MW of fusion power in its plasma The world record for fusion power in a magnetic confinement fusion device is held by the European tokamak JET. In 1997, JET produced 16 MW of fusion power from a total input heating power of 24 MW (Q=0.67). ITER is designed to yield in its plasma a ten-fold return on power (Q=10), or 500 MW of fusion power from 50 MW of input heating power. ITER will not convert the heating power it produces as electricity, but—as the first of all fusion experiments in history to produce net energy gain across the plasma—it will prepare the way for the machines that can.
3) Contribute to the demonstration of the integrated operation of technologies for a fusion power plant ITER will bridge the gap between today's smaller-scale experimental fusion devices and the demonstration fusion power plants of the future. Scientists will be able to study plasmas under conditions similar to those expected in a future power plant and test technologies such as heating, control, diagnostics, cryogenics and remote maintenance.
4) Test tritium breeding One of the missions for the later stages of ITER operation is to demonstrate the feasibility of producing tritium within the vacuum vessel. The world supply of tritium (used with deuterium to fuel the fusion reaction) is not sufficient to cover the needs of future power plants. ITER will provide a unique opportunity to test mockup in-vessel tritium breeding blankets in a real fusion environment.
5) Demonstrate the safety characteristics of a fusion device ITER achieved an important landmark in fusion history when, in 2012, the ITER Organization was licensed as a nuclear operator in France based on the rigorous and impartial examination of its safety files. One of the primary goals of ITER operation is to demonstrate the control of the plasma and the fusion reactions with negligible consequences to the environment.
WHAT IS FUSION?
Fusion is the energy source of the Sun and stars. In the tremendous heat and gravity at the core of these stellar bodies, hydrogen nuclei collide, fuse into heavier helium atoms and release tremendous amounts of energy in the process.
Twentieth-century fusion science identified the most efficient fusion reaction in the laboratory setting to be the reaction between two hydrogen isotopes, deuterium (D) and tritium (T), as the DT fusion reaction produces the highest energy gain at the "lowest" temperatures.
Three conditions must be fulfilled to achieve fusion in a laboratory: very high temperature (on the order of 150,000,000 °C); sufficient plasma particle density (to increase the likelihood that collisions do occur); and sufficient confinement time (to hold the plasma, which has a propensity to expand, within a defined volume).
At extreme temperatures, electrons are separated from nuclei and a gas becomes a plasma—often referred to as the fourth state of matter. Fusion plasmas provide the environment in which light elements can fuse and yield energy.
In a tokamak device, powerful magnetic fields are used to confine and control the plasma.
Visualization courtesy of Jamison Daniel, Oak Ridge Leadership Computing Facility
Power plants today rely either on fossil fuels, nuclear fission, or renewable sources like wind or water. Whatever the energy source, the plants generate electricity by converting mechanical power, such as the rotation of a turbine, into electrical power. In a coal-fired steam station, the combustion of coal turns water into steam and the steam in turn drives turbine generators to produce electricity.
The tokamak is an experimental machine designed to harness the energy of fusion. Inside a tokamak, the energy produced through the fusion of atoms is absorbed as heat in the walls of the vessel. Just like a conventional power plant, a fusion power plant will use this heat to produce steam and then electricity by way of turbines and generators.
The heart of a tokamak is its doughnut-shaped vacuum chamber. Inside, under the influence of extreme heat and pressure, gaseous hydrogen fuel becomes a plasma—the very environment in which hydrogen atoms can be brought to fuse and yield energy. (You can read more on this particular state of matter here.) The charged particles of the plasma can be shaped and controlled by the massive magnetic coils placed around the vessel; physicists use this important property to confine the hot plasma away from the vessel walls. The term "tokamak" comes to us from a Russian acronym that stands for "toroidal chamber with magnetic coils."
First developed by Soviet research in the late 1950s, the tokamak has been adopted around the world as the most promising configuration of magnetic fusion device. ITER will be the world's largest tokamak—twice the size of the largest machine currently in operation, with six times the plasma chamber volume.
See the Machine section for more on the Tokamak and its components.
WHO IS PARTICIPATING?
The ITER Project is a globe-spanning collaboration of 35 nations.
The ITER Members China, the European Union (through Euratom), India, Japan, Korea, Russia and the United States have combined resources to conquer one of the greatest frontiers in science—reproducing on Earth the boundless energy that fuels the Sun and the stars.
As signatories to the ITER Agreement, concluded in 2006, the seven Members will share the cost of project construction, operation and decommissioning. They also share the experimental results and any intellectual property generated by the fabrication, construction and operation phases.
Europe is responsible for the largest portion of construction costs (45.6 percent); the remainder is shared equally by China, India, Japan, Korea, Russia and the US (9.1 percent each). The Members deliver very little monetary contribution to the project: instead, nine-tenths of contributions will be delivered to the ITER Organization in the form of completed components, systems or buildings.
Taken together, the ITER Members represent three continents, over 40 languages, half of the world's population and 73 percent of global gross domestic product. In the offices of the ITER Organization and those of the seven Domestic Agencies, in laboratories and in industry, literally thousands of people are working toward the success of ITER. A recent review indicated that, with all contracting organizations included, individuals from 90 countries are working on the ITER site.
The ITER Organization has also concluded non-Member technical cooperation agreements with Australia (through the Australian Nuclear Science and Technology Organisation, ANSTO, in 2016) and Kazakhstan (through Kazakhstan's National Nuclear Centre in 2017); a Memorandum of Understanding with Canada agreeing to explore the possibility of future cooperation and a Cooperation Agreement with the Thailand Institute of Nuclear Technology (2018); as well as nearly 100 Cooperation Agreements with international organizations, national laboratories, universities and schools (see the full list at the end of the latest Annual Report).
See the Members page for links to the seven Domestic Agencies.
WHEN WILL EXPERIMENTS BEGIN?
On a 42-hectare site in the south of France, building has been underway since 2010. (See the Construction pages of the ITER web.) The central Tokamak Building was handed over to the ITER Organization in March 2020 for the start of machine assembly. The first major event of this new phase was the installation of the 1,250-tonne cryostat base in May 2020.
The ITER Organization is now overseeing the integration and assembly of components delivered to the ITER site by the seven ITER Members. This includes the assembly of the ITER Tokamak, with its estimated one million components, and the parallel installation and integration of plant systems such as radio frequency heating, fuel cycle, cryogenic, cooling water, vacuum, control, and high voltage electrical.
Hundreds of thousands of assembly tasks, organized into construction work packages, have been carefully planned and organized by ITER engineers and schedulers. In its role as overall assembly integrator, the ITER Organization is assisted by several major contractors. (See the Assembly pages of the ITER web.)
Update July 2024: At the 34th Meeting of the ITER Council in June 2024, the ITER Organization presented a new baseline proposal to replace the plan that had been used as a reference since 2016. The new baseline prioritizes a robust start to scientific exploitation with a more complete machine than initially planned, with a divertor, blanket shield blocks and other key components and systems in place in time for the first operational phase. That phase—Start of Research Operation—features hydrogen and deuterium-deuterium plasmas that culminate in the operation of the machine in long pulses at full magnetic energy and plasma current. In the new plan, the achievement of full magnetic energy in 2036 represents a delay of three years relative to the 2016 reference, while the start of the deuterium-tritium operation phase in 2039 represents a delay of four years. This proposed baseline will now be further evaluated, including the increased cost and the schedule implications driven by this new approach, before the ITER Council convenes again in November 2024. (See more detail in this article.)
ITER Timeline
2005 Decision to site the project in France
2006 Signature of the ITER Agreement
2007 Formal creation of the ITER Organization
2007-2009 Land clearing and levelling
2008 Component fabrication begins
2010-2014 Ground support structure and seismic foundations for the Tokamak Complex
2010-2024 Construction of ITER plant and auxiliary buildings (excepting the Hot Cell Facility)
2012 Nuclear licensing milestone: ITER becomes a Basic Nuclear Installation under French law
2015... Largest components are transported along the ITER Itinerary
2020 Machine assembly begins
2023 Completion of Tokamak Building civil works
2024 (June) Updated ITER baseline proposal submitted to the ITER Council
This large-bore, full-scale high-temperature superconducting magnet designed and built by Commonwealth Fusion Systems and MIT’s Plasma Science and Fusion Center (PSFC) has demonstrated a record-breaking 20 tesla magnetic field. It is the strongest fusion magnet in the world. Credit: Gretchen Ertl, CFS/MIT-PSFC, 2021
It was a moment three years in the making, based on intensive research and design work: On Sept. 5, for the first time, a large high-temperature superconducting electromagnet was ramped up to a field strength of 20 tesla, the most powerful magnetic field of its kind ever created on Earth. That successful demonstration helps resolve the greatest uncertainty in the quest to build the world's first fusion power plant that can produce more power than it consumes, according to the project's leaders at MIT and startup company Commonwealth Fusion Systems (CFS).
That advance paves the way, they say, for the long-sought creation of practical, inexpensive, carbon-free power plants that could make a major contribution to limiting the effects of global climate change.
"Fusion in a lot of ways is the ultimate clean energy source," says Maria Zuber, MIT's vice president for research and E. A. Griswold Professor of Geophysics. "The amount of power that is available is really game-changing." The fuel used to create fusion energy comes from water, and "the Earth is full of water—it's a nearly unlimited resource. We just have to figure out how to utilize it."
Developing the new magnet is seen as the greatest technological hurdle to making that happen; its successful operation now opens the door to demonstrating fusion in a lab on Earth, which has been pursued for decades with limited progress. With the magnet technology now successfully demonstrated, the MIT-CFS collaboration is on track to build the world's first fusion device that can create and confine a plasma that produces more energy than it consumes. That demonstration device, called SPARC, is targeted for completion in 2025.
"The challenges of making fusion happen are both technical and scientific," says Dennis Whyte, director of MIT's Plasma Science and Fusion Center, which is working with CFS to develop SPARC. But once the technology is proven, he says, "it's an inexhaustible, carbon-free source of energy that you can deploy anywhere and at any time. It's really a fundamentally new energy source."
Whyte, who is the Hitachi America Professor of Engineering, says this week's demonstration represents a major milestone, addressing the biggest questions remaining about the feasibility of the SPARC design. "It's really a watershed moment, I believe, in fusion science and technology," he says.
Collaborative team working on the magnet inside the test stand housed at MIT. Research, construction and testing of this magnet has been the single largest activity for the SPARC team, which has grown to include 270 members. Credit: Gretchen Ertl, CFS/MIT-PSFC, 2021
The sun in a bottle
Fusion is the process that powers the sun: the merger of two small atoms to make a larger one, releasing prodigious amounts of energy. But the process requires temperatures far beyond what any solid material could withstand. To capture the sun's power source here on Earth, what's needed is a way of capturing and containing something that hot—100,000,000 degrees or more—by suspending it in a way that prevents it from coming into contact with anything solid.
That's done through intense magnetic fields, which form a kind of invisible bottle to contain the hot swirling soup of protons and electrons, called a plasma. Because the particles have an electric charge, they are strongly controlled by the magnetic fields, and the most widely used configuration for containing them is a donut-shaped device called a tokamak. Most of these devices have produced their magnetic fields using conventional electromagnets made of copper, but the latest and largest version under construction in France, called ITER, uses what are known as low-temperature superconductors.
The major innovation in the MIT-CFS fusion design is the use of high-temperature superconductors, which enable a much stronger magnetic field in a smaller space. This design was made possible by a new kind of superconducting material that became commercially available a few years ago. The idea initially arose as a class project in a nuclear engineering class taught by Whyte. The idea seemed so promising that it continued to be developed over the next few iterations of that class, leading to the ARC power plant design concept in early 2015. SPARC, designed to be about half the size of ARC, is a testbed to prove the concept before construction of the full-size, power-producing plant.
Discover the latest in science, tech, and space with over 100,000 subscribers who rely on Phys.org for daily insights. Sign up for our free newsletter and get updates on breakthroughs, innovations, and research that matter—daily or weekly.
Until now, the only way to achieve the colossally powerful magnetic fields needed to create a magnetic "bottle" capable of containing plasma heated up to hundreds of millions of degrees was to make them larger and larger. But the new high-temperature superconductor material, made in the form of a flat, ribbon-like tape, makes it possible to achieve a higher magnetic field in a smaller device, equaling the performance that would be achieved in an apparatus 40 times larger in volume using conventional low-temperature superconducting magnets. That leap in power versus size is the key element in ARC's revolutionary design.
The use of the new high-temperature superconducting magnets makes it possible to apply decades of experimental knowledge gained from the operation of tokamak experiments, including MIT's own Alcator series. The new approach uses a well-known design but scales everything down to about half the linear size and still achieves the same operational conditions because of the higher magnetic field.
A series of scientific papers published last year outlined the physical basis and, by simulation, confirmed the viability of the new fusion device. The papers showed that, if the magnets worked as expected, the whole fusion system should indeed produce net power output, for the first time in decades of fusion research.
Martin Greenwald, deputy director and senior research scientist at the PSFC, says unlike some other designs for fusion experiments, "the niche that we were filling was to use conventional plasma physics, and conventional tokamak designs and engineering, but bring to it this new magnet technology. So, we weren't requiring innovation in a half-dozen different areas. We would just innovate on the magnet, and then apply the knowledge base of what's been learned over the last decades."
That combination of scientifically established design principles and game-changing magnetic field strength is what makes it possible to achieve a plant that could be economically viable and developed on a fast track. "It's a big moment," says Bob Mumgaard, CEO of CFS. "We now have a platform that is both scientifically very well-advanced, because of the decades of research on these machines, and also commercially very interesting. What it does is allow us to build devices faster, smaller, and at less cost," he says of the successful magnet demonstration.
Proof of the concept
Bringing that new magnet concept to reality required three years of intensive work on design, establishing supply chains, and working out manufacturing methods for magnets that may eventually need to be produced by the thousands.
"We built a first-of-a-kind, superconducting magnet. It required a lot of work to create unique manufacturing processes and equipment. As a result, we are now well-prepared to ramp-up for SPARC production," says Joy Dunn, head of operations at CFS. "We started with a physics model and a CAD design, and worked through lots of development and prototypes to turn a design on paper into this actual physical magnet." That entailed building manufacturing capabilities and testing facilities, including an iterative process with multiple suppliers of the superconducting tape, to help them reach the ability to produce material that met the needed specifications—and for which CFS is now overwhelmingly the world's biggest user.
They worked with two possible magnet designs in parallel, both of which ended up meeting the design requirements, she says. "It really came down to which one would revolutionize the way that we make superconducting magnets, and which one was easier to build." The design they adopted clearly stood out in that regard, she says.
In this test, the new magnet was gradually powered up in a series of steps until reaching the goal of a 20 tesla magnetic field—the highest field strength ever for a high-temperature superconducting fusion magnet. The magnet is composed of 16 plates stacked together, each one of which by itself would be the most powerful high-temperature superconducting magnet in the world.
"Three years ago we announced a plan," says Mumgaard, "to build a 20-tesla magnet, which is what we will need for future fusion machines." That goal has now been achieved, right on schedule, even with the pandemic, he says.
Citing the series of physics papers published last year, Brandon Sorbom, the chief science officer at CFS, says "basically the papers conclude that if we build the magnet, all of the physics will work in SPARC. So, this demonstration answers the question: Can they build the magnet? It's a very exciting time! It's a huge milestone."
The next step will be building SPARC, a smaller-scale version of the planned ARC power plant. The successful operation of SPARC will demonstrate that a full-scale commercial fusion power plant is practical, clearing the way for rapid design and construction of that pioneering device can then proceed full speed.
Zuber says that "I now am genuinely optimistic that SPARC can achieve net positive energy, based on the demonstrated performance of the magnets. The next step is to scale up, to build an actual power plant. There are still many challenges ahead, not the least of which is developing a design that allows for reliable, sustained operation. And realizing that the goal here is commercialization, another major challenge will be economic. How do you design these power plants so it will be cost effective to build and deploy them?"
Someday in a hoped-for future, when there may be thousands of fusion plants powering clean electric grids around the world, Zuber says, "I think we're going to look back and think about how we got there, and I think the demonstration of the magnet technology, for me, is the time when I believed that, wow, we can really do this."
The successful creation of a power-producing fusion device would be a tremendous scientific achievement, Zuber notes. But that's not the main point. "None of us are trying to win trophies at this point. We're trying to keep the planet livable."
Argomento precedente
.jpg)
Primo 
_CIA_World_Factbook_map.png)
_(41783636452).jpg)
.jpg)
This large-bore, full-scale high-temperature superconducting magnet designed and built by Commonwealth Fusion Systems and MIT’s Plasma Science and Fusion Center (PSFC) has demonstrated a record-breaking 20 tesla magnetic field. It is the strongest fusion magnet in the world. Credit: Gretchen Ertl, CFS/MIT-PSFC, 2021
Collaborative team working on the magnet inside the test stand housed at MIT. Research, construction and testing of this magnet has been the single largest activity for the SPARC team, which has grown to include 270 members. Credit: Gretchen Ertl, CFS/MIT-PSFC, 2021