FUSION-SCI-FI-TEK
Contract for ITER vacuum vessel assembly
05 March 2024
The Sino-French TAC-1 consortium - led by China National Nuclear Corporation subsidiary China Nuclear Power Engineering and including Framatome - has been awarded a contract to assemble the vacuum chamber modules of the International Thermonuclear Experimental Reactor (ITER), under construction in Cadarache, southern France.
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Representatives from the TAC-1 consortium companies (Image: CNNC)ITER's plasma chamber, or vacuum vessel, houses the fusion reactions and acts as a first safety containment barrier. With an interior volume of 1400 cubic metres, it will be formed from nine wedge-shaped steel sectors that measure more than 14 metres in height and weigh 440 tonnes. The ITER vacuum vessel, once assembled, will have an outer diameter of 19.4 metres, a height of 11.4 metres, and weigh approximately 5200 tonnes. With the subsequent installation of in-vessel components such as the blanket and the divertor, the vacuum vessel will weigh 8500 tonnes.
The fabrication of the vacuum vessel sectors is shared between Europe (five sectors) and South Korea (four sectors). Vacuum vessel sector 6, at the centre of the assembly, and associated thermal shielding has already been manufactured and delivered by the Korean Domestic Agency. The first sector, 5, being supplied by Europe has now been manufactured in Italy and is undergoing factory acceptance tests prior to being shipped to the construction site.
Shen Yanfeng, deputy general manager of China National Nuclear Corporation, noted that the signing of the agreement means that the Chinese-French consortium has become the sole contractor for the installation of the Tokamak machine of the ITER project.
China formally agreed to join the ITER project in 2006. Since 2008, China has undertaken 18 procurement package tasks of research and manufacture, involving key components such as the magnet support system, magnet feeder system, power supply system, glow discharge cleaning system, gas injection system, and the 'first wall' of the reactor core, which is capable of withstanding extremely high temperatures.
In September 2019, the five-member Chinese-French consortium signed the TAC-1 installation contract with ITER, marking the beginning of China's in-depth participation in the tokamak. TAC-1 focuses on the assembly of the cryostat and cryostat thermal shield, the magnet feeders, the central solenoid, poloidal field and correction coil magnets, and cooling structures and instrumentation.
ITER is a major international project to build a tokamak fusion device in Cadarache, France, designed to prove the feasibility of fusion as a large-scale and carbon-free source of energy. The goal of ITER is to operate at 500 MW (for at least 400 seconds continuously) with 50 MW of plasma heating power input. It appears that an additional 300 MWe of electricity input may be required in operation. No electricity will be generated at ITER.
Thirty-five nations are collaborating to build ITER - the European Union is contributing almost half of the cost of its construction, while the other six members (China, India, Japan, South Korea, Russia and the USA) are contributing equally to the rest. Construction began in 2010 and the original 2018 first plasma target date was put back to 2025 by the ITER council in 2016. In June last year, the ITER Organisation was expected to reveal a revised timeline for the project but instead put back by a year an announcement on an updated timeline.
The revamped project plan for ITER - with modifications to its configuration, phased installation and new research schedule - is being finalised ahead of being submitted to the ITER Council in June.
Researched and written by World Nuclear News
MIT’s Superconducting Magnets Mark Major Fusion Milestone
- MIT researchers achieve a world-record magnetic field strength using high-temperature superconducting magnets, demonstrating their potential for compact fusion power plants.
- The comprehensive study, detailed in six peer-reviewed papers, validates the magnet's design and performance, offering a solid foundation for future fusion devices.
- By leveraging new materials and innovative design approaches, MIT and its partners pave the way for practical fusion energy, promising a cleaner, limitless energy source for the future.
A detailed report by researchers at PSFC and MIT spinout company Commonwealth Fusion Systems (CFS), published in a collection of six peer-reviewed papers in a special edition of the March issue of IEEE Transactions on Applied Superconductivity. Together, the papers describe the design and fabrication of the magnet and the diagnostic equipment needed to evaluate its performance, as well as the lessons learned from the process. Overall, the team found, the predictions and computer modeling were spot-on, verifying that the magnet’s unique design elements could serve as the foundation for a fusion power plant. Back during the predawn hours of Sept. 5, 2021, engineers achieved a major milestone in the labs of MIT’s Plasma Science and Fusion Center (PSFC), when a new type of magnet, made from high-temperature superconducting material, achieved a world-record magnetic field strength of 20 tesla for a large-scale magnet. That’s the intensity needed to build a fusion power plant that is expected to produce a net output of power and potentially usher in an era of virtually limitless power production.
The test was immediately declared a success, having met all the criteria established for the design of the new fusion device, dubbed SPARC, for which the magnets are the key enabling technology. Champagne corks popped as the weary team of experimenters, who had labored long and hard to make the achievement possible, celebrated their accomplishment.
But that was far from the end of the process. Over the ensuing months, the team tore apart and inspected the components of the magnet, pored over and analyzed the data from hundreds of instruments that recorded details of the tests, and performed two additional test runs on the same magnet, ultimately pushing it to its breaking point in order to learn the details of any possible failure modes.
Enabling practical fusion power
The successful test of the magnet, said Hitachi America Professor of Engineering Dennis Whyte, who recently stepped down as director of the PSFC, was “the most important thing, in my opinion, in the last 30 years of fusion research.”
Before the Sept. 2021 demonstration, the best-available superconducting magnets were powerful enough to potentially achieve fusion energy – but only at sizes and costs that could never be practical or economically viable. Then, when the tests showed the practicality of such a strong magnet at a greatly reduced size, “overnight, it basically changed the cost per watt of a fusion reactor by a factor of almost 40 in one day,” Whyte said.
“Now fusion has a chance,” Whyte added. Tokamaks, the most widely used design for experimental fusion devices, “have a chance, in my opinion, of being economical because you’ve got a quantum change in your ability, with the known confinement physics rules, about being able to greatly reduce the size and the cost of objects that would make fusion possible.”
The comprehensive data and analysis from the PSFC’s magnet test, as detailed in the six new papers, has demonstrated that plans for a new generation of fusion devices – the one designed by MIT and CFS, as well as similar designs by other commercial fusion companies – are built on a solid foundation in science.
The superconducting breakthrough
Fusion, the process of combining light atoms to form heavier ones, powers the sun and stars, but harnessing that process on Earth has proved to be a daunting challenge, with decades of hard work and many billions of dollars spent on experimental devices. The long-sought, but never yet achieved, goal is to build a fusion power plant that produces more energy than it consumes. Such a power plant could produce electricity without emitting greenhouse gases during operation, and generating very little radioactive waste. Fusion’s fuel, a form of hydrogen that can be derived from seawater, is virtually limitless.
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But to make it work requires compressing the fuel at extraordinarily high temperatures and pressures, and since no known material could withstand such temperatures, the fuel must be held in place by extremely powerful magnetic fields. Producing such strong fields requires superconducting magnets, but all previous fusion magnets have been made with a superconducting material that requires frigid temperatures of about 4º above absolute zero (4 kelvins, or -270º Celsius).
In the last few years, a newer material nicknamed REBCO, for rare-earth barium copper oxide, was added to fusion magnets, and allows them to operate at 20 kelvins, a temperature that despite being only 16 kelvins warmer, brings significant advantages in terms of material properties and practical engineering.
Taking advantage of this new higher-temperature superconducting material was not just a matter of substituting it in existing magnet designs. Instead, “it was a rework from the ground up of almost all the principles that you use to build superconducting magnets,” Whyte said. The new REBCO material is “extraordinarily different than the previous generation of superconductors. You’re not just going to adapt and replace, you’re actually going to innovate from the ground up.” The new papers in Transactions on Applied Superconductivity describe the details of that redesign process, now that patent protection is in place.
A key innovation: no insulation
One of the dramatic innovations, which had many others in the field skeptical of its chances of success, was the elimination of insulation around the thin, flat ribbons of superconducting tape that formed the magnet. Like virtually all electrical wires, conventional superconducting magnets are fully protected by insulating material to prevent short-circuits between the wires. But in the new magnet, the tape was left completely bare; the engineers relied on REBCO’s much greater conductivity to keep the current flowing through the material.
Zach Hartwig, the Robert N. Noyce Career Development Professor in the Department of Nuclear Science and Engineering. Hartwig has a co-appointment at the PSFC and is the head of its engineering group, which led the magnet development project explained, “When we started this project, in let’s say 2018, the technology of using high-temperature superconductors to build large-scale high-field magnets was in its infancy. The state of the art was small benchtop experiments, not really representative of what it takes to build a full-size thing. Our magnet development project started at benchtop scale and ended up at full scale in a short amount of time,” he added, noting that the team built a 20,000-pound magnet that produced a steady, even magnetic field of just over 20 tesla – far beyond any such field ever produced at large scale.
“The standard way to build these magnets is you would wind the conductor and you have insulation between the windings, and you need insulation to deal with the high voltages that are generated during off-normal events such as a shutdown.” Eliminating the layers of insulation, he says, “has the advantage of being a low-voltage system. It greatly simplifies the fabrication processes and schedule.” It also leaves more room for other elements, such as more cooling or more structure for strength.
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The magnet assembly is a slightly smaller-scale version of the ones that will form the donut-shaped chamber of the SPARC fusion device now being built by CFS in Devens, Massachusetts. It consists of 16 plates, called pancakes, each bearing a spiral winding of the superconducting tape on one side and cooling channels for helium gas on the other.
But the no-insulation design was considered risky, and a lot was riding on the test program. “This was the first magnet at any sufficient scale that really probed what is involved in designing and building and testing a magnet with this so-called no-insulation no-twist technology,” Hartwig said. “It was very much a surprise to the community when we announced that it was a no-insulation coil.”
Pushing to the limit … and beyond
The initial test, described in previous papers, proved that the design and manufacturing process not only worked but was highly stable – something that some researchers had doubted. The next two test runs, also performed in late 2021, then pushed the device to the limit by deliberately creating unstable conditions, including a complete shutoff of incoming power that can lead to a catastrophic overheating. Known as quenching, this is considered a worst-case scenario for the operation of such magnets, with the potential to destroy the equipment.
Part of the mission of the test program, Hartwig said, was “to actually go off and intentionally quench a full-scale magnet, so that we can get the critical data at the right scale and the right conditions to advance the science, to validate the design codes, and then to take the magnet apart and see what went wrong, why did it go wrong, and how do we take the next iteration toward fixing that . . . it was a very successful test.”
That final test, which ended with the melting of one corner of one of the 16 pancakes, produced a wealth of new information, Hartwig noted. For one thing, they had been using several different computational models to design and predict the performance of various aspects of the magnet’s performance, and for the most part, the models agreed in their overall predictions and were well-validated by the series of tests and real-world measurements. But in predicting the effect of the quench, the model predictions diverged, so it was necessary to get the experimental data to evaluate the models’ validity.
“The highest-fidelity models that we had predicted almost exactly how the magnet would warm up, to what degree it would warm up as it started to quench, and where would the resulting damage to the magnet would be,” he noted. As described in detail in one of the new reports, “That test actually told us exactly the physics that was going on, and it told us which models were useful going forward and which to leave by the wayside because they’re not right.”
Whyte commented, “Basically we did the worst thing possible to a coil, on purpose, after we had tested all other aspects of the coil performance. And we found that most of the coil survived with no damage,” while one isolated area sustained some melting. “It’s like a few percent of the volume of the coil that got damaged.” And that led to revisions in the design that are expected to prevent such damage in the actual fusion device magnets, even under the most extreme conditions.
Hartwig emphasizes that a major reason the team was able to accomplish such a radical new record-setting magnet design, and get it right the very first time and on a breakneck schedule, was thanks to the deep level of knowledge, expertise, and equipment accumulated over decades of operation of the Alcator C-Mod tokamak, the Francis Bitter Magnet Laboratory, and other work carried out at PSFC. “This goes to the heart of the institutional capabilities of a place like this,” he said. “We had the capability, the infrastructure, and the space and the people to do these things under one roof.”
The collaboration with CFS was also key, he said, with MIT and CFS combining the most powerful aspects of an academic institution and private company to do things together that neither could have done on their own. “For example, one of the major contributions from CFS was leveraging the power of a private company to establish and scale up a supply chain at an unprecedented level and timeline for the most critical material in the project: 300 kilometers (186 miles) of high-temperature superconductor, which was procured with rigorous quality control in under a year, and integrated on schedule into the magnet.”
The integration of the two teams, those from MIT and those from CFS, also was crucial to the success, he said. “We thought of ourselves as one team, and that made it possible to do what we did.”
**
It sounds like the past 2 ½ years have proven the immense value of the rare-earth barium copper oxide development. Even more impressive is that the team and its funders tried the no insulation technique and succeeded.
They have just put much better confinement power into the fusion effort.
And it won’t be just the tokomak devices getting the upgrade. Many of us still have a lot of confidence in the potential of the Robert Bussard based device and others.
Then there is the likelihood that superconducting magnet development will make more strides to higher temperatures.
Meanwhile Eric Lerner is working the plasma confinement idea and is improving steadily.
There just might be power plant choices sooner that the cynics could imagine.
By Brian Westenhaus via New Energy and Fuel
Tests show high-temperature superconducting magnets are ready for fusion
Detailed study of magnets built by MIT and Commonwealth Fusion Systems confirms they meet requirements for an economic, compact fusion power plant.
NEWS RELEASE
MASSACHUSETTS INSTITUTE OF TECHNOLOGY
IMAGE:
IN MIT’S PLASMA SCIENCE AND FUSION CENTER, THE NEW MAGNETS ACHIEVED A WORLD-RECORD MAGNETIC FIELD STRENGTH OF 20 TESLA FOR A LARGE-SCALE MAGNET.
view moreCREDIT: IMAGE: GRETCHEN ERTL
In the predawn hours of Sept. 5, 2021, engineers achieved a major milestone in the labs of MIT’s Plasma Science and Fusion Center (PSFC), when a new type of magnet, made from high-temperature superconducting material, achieved a world-record magnetic field strength of 20 tesla for a large-scale magnet. That’s the intensity needed to build a fusion power plant that is expected to produce a net output of power and potentially usher in an era of virtually limitless power production.
The test was immediately declared a success, having met all the criteria established for the design of the new fusion device, dubbed SPARC, for which the magnets are the key enabling technology. Champagne corks popped as the weary team of experimenters, who had labored long and hard to make the achievement possible, celebrated their accomplishment.
But that was far from the end of the process. Over the ensuing months, the team tore apart and inspected the components of the magnet, pored over and analyzed the data from hundreds of instruments that recorded details of the tests, and performed two additional test runs on the same magnet, ultimately pushing it to its breaking point in order to learn the details of any possible failure modes.
All of this work has now culminated in a detailed report by researchers at PSFC and MIT spinout company Commonwealth Fusion Systems (CFS), published in a collection of six peer-reviewed papers in a special edition of the March issue of IEEE Transactions on Applied Superconductivity. Together, the papers describe the design and fabrication of the magnet and the diagnostic equipment needed to evaluate its performance, as well as the lessons learned from the process. Overall, the team found, the predictions and computer modeling were spot-on, verifying that the magnet’s unique design elements could serve as the foundation for a fusion power plant.
Enabling practical fusion power
The successful test of the magnet, says Hitachi America Professor of Engineering Dennis Whyte, who recently stepped down as director of the PSFC, was “the most important thing, in my opinion, in the last 30 years of fusion research.”
Before the Sept. 5 demonstration, the best-available superconducting magnets were powerful enough to potentially achieve fusion energy — but only at sizes and costs that could never be practical or economically viable. Then, when the tests showed the practicality of such a strong magnet at a greatly reduced size, “overnight, it basically changed the cost per watt of a fusion reactor by a factor of almost 40 in one day,” Whyte says.
“Now fusion has a chance,” Whyte adds. Tokamaks, the most widely used design for experimental fusion devices, “have a chance, in my opinion, of being economical because you’ve got a quantum change in your ability, with the known confinement physics rules, about being able to greatly reduce the size and the cost of objects that would make fusion possible.”
The comprehensive data and analysis from the PSFC’s magnet test, as detailed in the six new papers, has demonstrated that plans for a new generation of fusion devices — the one designed by MIT and CFS, as well as similar designs by other commercial fusion companies — are built on a solid foundation in science.
The superconducting breakthrough
Fusion, the process of combining light atoms to form heavier ones, powers the sun and stars, but harnessing that process on Earth has proved to be a daunting challenge, with decades of hard work and many billions of dollars spent on experimental devices. The long-sought, but never yet achieved, goal is to build a fusion power plant that produces more energy than it consumes. Such a power plant could produce electricity without emitting greenhouse gases during operation, and generating very little radioactive waste. Fusion’s fuel, a form of hydrogen that can be derived from seawater, is virtually limitless.
But to make it work requires compressing the fuel at extraordinarily high temperatures and pressures, and since no known material could withstand such temperatures, the fuel must be held in place by extremely powerful magnetic fields. Producing such strong fields requires superconducting magnets, but all previous fusion magnets have been made with a superconducting material that requires frigid temperatures of about 4 degrees above absolute zero (4 kelvins, or -270 degrees Celsius). In the last few years, a newer material nicknamed REBCO, for rare-earth barium copper oxide, was added to fusion magnets, and allows them to operate at 20 kelvins, a temperature that despite being only 16 kelvins warmer, brings significant advantages in terms of material properties and practical engineering.
Taking advantage of this new higher-temperature superconducting material was not just a matter of substituting it in existing magnet designs. Instead, “it was a rework from the ground up of almost all the principles that you use to build superconducting magnets,” Whyte says. The new REBCO material is “extraordinarily different than the previous generation of superconductors. You’re not just going to adapt and replace, you’re actually going to innovate from the ground up.” The new papers in Transactions on Applied Superconductivity describe the details of that redesign process, now that patent protection is in place.
A key innovation: no insulation
One of the dramatic innovations, which had many others in the field skeptical of its chances of success, was the elimination of insulation around the thin, flat ribbons of superconducting tape that formed the magnet. Like virtually all electrical wires, conventional superconducting magnets are fully protected by insulating material to prevent short-circuits between the wires. But in the new magnet, the tape was left completely bare; the engineers relied on REBCO’s much greater conductivity to keep the current flowing through the material.
“When we started this project, in let’s say 2018, the technology of using high-temperature superconductors to build large-scale high-field magnets was in its infancy,” says Zach Hartwig, the Robert N. Noyce Career Development Professor in the Department of Nuclear Science and Engineering. Hartwig has a co-appointment at the PSFC and is the head of its engineering group, which led the magnet development project. “The state of the art was small benchtop experiments, not really representative of what it takes to build a full-size thing. Our magnet development project started at benchtop scale and ended up at full scale in a short amount of time,” he adds, noting that the team built a 20,000-pound magnet that produced a steady, even magnetic field of just over 20 tesla — far beyond any such field ever produced at large scale.
“The standard way to build these magnets is you would wind the conductor and you have insulation between the windings, and you need insulation to deal with the high voltages that are generated during off-normal events such as a shutdown.” Eliminating the layers of insulation, he says, “has the advantage of being a low-voltage system. It greatly simplifies the fabrication processes and schedule.” It also leaves more room for other elements, such as more cooling or more structure for strength.
The magnet assembly is a slightly smaller-scale version of the ones that will form the donut-shaped chamber of the SPARC fusion device now being built by CFS in Devens, Massachusetts. It consists of 16 plates, called pancakes, each bearing a spiral winding of the superconducting tape on one side and cooling channels for helium gas on the other.
But the no-insulation design was considered risky, and a lot was riding on the test program. “This was the first magnet at any sufficient scale that really probed what is involved in designing and building and testing a magnet with this so-called no-insulation no-twist technology,” Hartwig says. “It was very much a surprise to the community when we announced that it was a no-insulation coil.”
Pushing to the limit … and beyond
The initial test, described in previous papers, proved that the design and manufacturing process not only worked but was highly stable — something that some researchers had doubted. The next two test runs, also performed in late 2021, then pushed the device to the limit by deliberately creating unstable conditions, including a complete shutoff of incoming power that can lead to a catastrophic overheating. Known as quenching, this is considered a worst-case scenario for the operation of such magnets, with the potential to destroy the equipment.
Part of the mission of the test program, Hartwig says, was “to actually go off and intentionally quench a full-scale magnet, so that we can get the critical data at the right scale and the right conditions to advance the science, to validate the design codes, and then to take the magnet apart and see what went wrong, why did it go wrong, and how do we take the next iteration toward fixing that. … It was a very successful test.”
That final test, which ended with the melting of one corner of one of the 16 pancakes, produced a wealth of new information, Hartwig says. For one thing, they had been using several different computational models to design and predict the performance of various aspects of the magnet’s performance, and for the most part, the models agreed in their overall predictions and were well-validated by the series of tests and real-world measurements. But in predicting the effect of the quench, the model predictions diverged, so it was necessary to get the experimental data to evaluate the models’ validity.
“The highest-fidelity models that we had predicted almost exactly how the magnet would warm up, to what degree it would warm up as it started to quench, and where would the resulting damage to the magnet would be,” he says. As described in detail in one of the new reports, “That test actually told us exactly the physics that was going on, and it told us which models were useful going forward and which to leave by the wayside because they’re not right.”
Whyte says, “Basically we did the worst thing possible to a coil, on purpose, after we had tested all other aspects of the coil performance. And we found that most of the coil survived with no damage,” while one isolated area sustained some melting. “It’s like a few percent of the volume of the coil that got damaged.” And that led to revisions in the design that are expected to prevent such damage in the actual fusion device magnets, even under the most extreme conditions.
Hartwig emphasizes that a major reason the team was able to accomplish such a radical new record-setting magnet design, and get it right the very first time and on a breakneck schedule, was thanks to the deep level of knowledge, expertise, and equipment accumulated over decades of operation of the Alcator C-Mod tokamak, the Francis Bitter Magnet Laboratory, and other work carried out at PSFC. “This goes to the heart of the institutional capabilities of a place like this,” he says. “We had the capability, the infrastructure, and the space and the people to do these things under one roof.”
The collaboration with CFS was also key, he says, with MIT and CFS combining the most powerful aspects of an academic institution and private company to do things together that neither could have done on their own. “For example, one of the major contributions from CFS was leveraging the power of a private company to establish and scale up a supply chain at an unprecedented level and timeline for the most critical material in the project: 300 kilometers (186 miles) of high-temperature superconductor, which was procured with rigorous quality control in under a year, and integrated on schedule into the magnet.”
The integration of the two teams, those from MIT and those from CFS, also was crucial to the success, he says. “We thought of ourselves as one team, and that made it possible to do what we did.”
Written by David L. Chandler, MIT News Office
Papers: Special issue on the SPARC Toroidal Field Model Coil Program
https://ieeexplore.ieee.org/xpl/tocresult.jsp?isnumber=10348035&punumber=77
JOURNAL
IEEE Transactions on Applied Superconductivity
ARTICLE TITLE
Special issue on the SPARC Toroidal Field Model Coil Program
One way to improve a fusion reaction: Use weaknesses as strengths
Scientists take advantage of imperfections in magnetic fields to enhance fusion plasma
In the Japanese art of Kintsugi, an artist takes the broken shards of a bowl and fuses them back together with gold to make a final product more beautiful than the original.
That idea is inspiring a new approach to managing plasma, the super-hot state of matter, for use as a power source. Scientists are using the imperfections in magnetic fields that confine a reaction to improve and enhance the plasma in an approach outlined in a new paper in the journal Nature Communications.
“This approach allows you to maintain a high-performance plasma, controlling instabilities in the core and the edge of the plasma simultaneously. That simultaneous control is particularly important and difficult to do. That’s what makes this work special,” said Joseph Snipes of the U.S. Department of Energy’s (DOE) Princeton Plasma Physics Laboratory (PPPL). He is PPPL’s deputy head of the Tokamak Experimental Science Department and was a co-author of the paper.
PPPL Physicist Seong-Moo Yang led the research team, which spans various institutions in the U.S. and South Korea. Yang says this is the first time any research team has validated a systematic approach to tailoring magnetic field imperfections to make the plasma suitable for use as a power source. These magnetic field imperfections are known as error fields.
“Our novel method identifies optimal error field corrections, enhancing plasma stability,” Yang said. “This method was proven to enhance plasma stability under different plasma conditions, for example, when the plasma was under conditions of high and low magnetic confinement.”
Errors that are hard to correct
Error fields are typically caused by minuscule defects in the magnetic coils of the device that holds the plasma, which is called a tokamak. Until now, error fields were only seen as a nuisance because even a very small error field could cause a plasma disruption that halts fusion reactions and can damage the walls of a fusion vessel. Consequently, fusion researchers have spent considerable time and effort meticulously finding ways to correct error fields.
“It’s quite difficult to eliminate existing error fields, so instead of fixing these coil irregularities, we can apply additional magnetic fields surrounding the fusion vessel in a process known as error field correction,” Yang said.
In the past, this approach would have also hurt the plasma’s core, making the plasma unsuitable for fusion power generation. This time, the researchers were able to eliminate instabilities at the edge of the plasma and maintain the stability of the core. The research is a prime example of how PPPL researchers are bridging the gap between today’s fusion technology and what will be needed to bring fusion power to the electrical grid.
“This is actually a very effective way of breaking the symmetry of the system, so humans can intentionally degrade the confinement. It’s like making a very tiny hole in a balloon so that it will not explode,” said SangKyeun Kim, a staff research scientist at PPPL and paper co-author. Just as air would leak out of a small hole in a balloon, a tiny quantity of plasma leaks out of the error field, which helps to maintain its overall stability.
Managing the core and the edge of the plasma simultaneously
One of the toughest parts of managing a fusion reaction is getting both the core and the edge of the plasma to behave at the same time. There are ideal zones for the temperature and density of the plasma in both regions, and hitting those targets while eliminating instabilities is tough.
This study demonstrates that adjusting the error fields can simultaneously stabilize both the core and the edge of the plasma. By carefully controlling the magnetic fields produced by the tokamak’s coils, the researchers could suppress edge instabilities, also known as edge localized modes (ELMs), without causing disruptions or a substantial loss of confinement.
“We are trying to protect the device,” said PPPL Staff Research Physicist Qiming Hu, an author of the paper.
Extending the research beyond KSTAR
The research was conducted using the KSTAR tokamak in South Korea, which stands out for its ability to adjust its magnetic error field configuration with great flexibility. This capability is crucial for experimenting with different error field configurations to find the most effective ones for stabilizing the plasma.
The researchers say their approach has significant implications for the design of future tokamak fusion pilot plants, potentially making them more efficient and reliable. They are currently working on an artificial intelligence (AI) version of their control system to make it more efficient.
“These models are fairly complex; they take a bit of time to calculate. But when you want to do something in a real-time control system, you can only afford a few milliseconds to do a calculation,” said Snipes. “Using AI, you can basically teach the system what to expect and be able to use that artificial intelligence to predict ahead of time what will be necessary to control the plasma and how to implement it in real-time.”
While their new paper highlights work done using KSTAR’s internal magnetic coils, Hu suggests future research with magnetic coils outside of the fusion vessel would be valuable because the fusion community is moving away from the idea of housing such coils inside the vacuum-sealed vessel due to the potential destruction of such components from the extreme heat of the plasma.
Researchers from the Korea Institute of Fusion Energy (KFE), Columbia University, and Seoul National University were also integral to the project.
The research was supported by: the U.S. Department of Energy under contract number DE-AC02-09CH11466; the Ministry of Science and ICT under the KFE R&D Program “KSTAR Experimental Collaboration and Fusion Plasma Research (KFE-EN2401-15)”; the National Research Foundation (NRF) grant No. RS-2023-00281272 funded through the Korean Ministry of Science, Information and Communication Technology and the New Faculty Startup Fund from Seoul National University; the NRF under grants No. 2019R1F1A1057545 and No. 2022R1F1A1073863; the National R&D Program through the NRF funded by the Ministry of Science & ICT (NRF-2019R1A2C1010757).
JOURNAL
Nature Communications
SUBJECT OF RESEARCH
Not applicable
ARTICLE TITLE
Tailoring tokamak error fields to control plasma instabilities and transport
INFUSE workshop gives private and public fusion partners a chance to network and share experiences
IMAGE:
PPPL’S HEAD OF SCIENCE EDUCATION ARTURO DOMINGUEZ (FAR RIGHT) TAKES A GROUP OF INFUSE WORKSHOP ATTENDEES ON A TOUR OF THE LAB.
view moreCREDIT: MICHAEL LIVINGSTON, PPPL
More than 120 people gathered for the 2024 Innovation Network for Fusion Energy (INFUSE) Workshop at the U.S. Department of Energy’s (DOE) Princeton Plasma Physics Laboratory (PPPL) from Feb. 27-28.
The event, which was sponsored by the DOE’s Office of Fusion Energy Sciences (FES), is a part of the INFUSE awards program that funds laboratories or universities so they can partner with private sector companies working on the science and technology solutions that will bring fusion energy to the power grid. To date, the DOE has granted 90 awards, with most ranging from $100,000 to $350,000 for a 12-month project.
“The INFUSE program continues to help bring together the accumulated knowledge and expertise developed in national labs and universities with the private companies that want to reduce risks and drive their technologies forward,” said Erik Gilson, INFUSE deputy director and head of PPPL’s Discovery Plasma Science Department. “These types of public-private partnerships really bring out the best in each sector. I’m excited to see what new partnerships emerge as the result of people networking at the workshop.”
Developing a system for using fusion as a source of electricity is as important as it is complex.
Fusion could support our ever-growing need for energy without contributing to carbon emissions. But the challenge is arduous and multifaceted, as fusion requires new materials, engineering and software.
“I believe we are going to conquer this issue of making fusion cheap enough for the market, but it would sure be nice if it were soon,” said PPPL Lab Director Steven Cowley during his opening remarks at the workshop.
Cowley said he believes part of overcoming the challenges to bringing fusion energy to the power grid is embracing public-private partnerships and noted that, ultimately, it will be private industry that brings fusion to the market efficiently. “We are here to support you,” he told workshop attendees.
“The tone of the meeting was set based on what we heard from the respondents to a survey from a previous virtual workshop, which showed the greatest need was for networking opportunities,” said Arnie Lumsdaine, INFUSE director and group leader of fusion engineering at Oak Ridge National Laboratory. Consequently, technical sessions were kept to a minimum, with the bulk of the two-day program offering opportunities for private companies to learn more about what each national lab had to offer and discuss collaboration possibilities.
Scott Hsu, senior advisor and lead fusion coordinator in the Office of the Under Secretary for Science and Innovation at the DOE, explained the elements essential to realizing President Joe Biden’s “Bold Decadal Vision” for fusion energy. “We want to ensure that fusion is a leader in supporting a clean energy transition,” said Hsu. This, he explained, requires everything from closing the science and technology gaps to building a fusion pilot plant, establishing reliable supply chains –– especially for fusion fuels, developing a waste management strategy, instituting regulatory frameworks, and establishing external partnerships, including with state and local governments, nongovernmental organizations, academia and the private sector.
Fermi National Accelerator Laboratory (Fermilab) Scientist Maria Baldini was among the many representatives from the national labs. “This workshop offers me a good opportunity to meet people in the private sector,” Baldini said. “We are trying to develop a program to study the properties of a new kind of conductor under different engineering constraints that would be used for fusion machines, and it would be good for me to know the people in the private sector who produce this conductor and try to think about how we can collaborate.”
In addition to opportunities to network, the workshop offered a lengthy question-and-answer session with Fusion Industry Association Chief Executive Officer Andrew Holland, tours of PPPL, technical sessions, presentations about successful INFUSE projects and information about the Cooperative Research and Development Agreement (CRADA) process.
PPPL’s Strategic Partnership Officer David Zimmerman was one of the speakers providing advice on the CRADA process. “You can see from the number of applications that the INFUSE program generates and the number of grant awards that it makes that this program is really driving public-private partnerships,” said Zimmerman. “I think it’s a fantastic mechanism program to advertise laboratory capabilities to fusion companies and to give laboratories an opportunity to engage with this exciting new fusion industry.”
Aaron Froese, a computational plasma physicist at General Fusion in British Columbia, Canada, said the INFUSE awards have allowed the company to extend research critical to advancing their magnetized target fusion technology for commercialization. In a General Fusion commercial power plant, the company says a plasma liner made of liquid lithium will improve device longevity (by shielding structural components from fast fusion neutrons), increase the tritium breeding ratio and act as the medium to transfer the kinetic energy from the compression drivers, addressing the significant barriers to commercialization. General Fusion has worked with several U.S. national labs under INFUSE awards, including PPPL, Oak Ridge National Laboratory and Savannah River National Laboratory. “The administration has been very receptive to our endeavors,” Froese said. “I think it’s a very well-run program.”
PPPL is mastering the art of using plasma — the fourth state of matter — to solve some of the world's toughest science and technology challenges. Nestled on Princeton University’s Forrestal Campus in Plainsboro, New Jersey, our research ignites innovation in a range of applications including fusion energy, nanoscale fabrication, quantum materials and devices, and sustainability science. The University manages the Laboratory for the U.S. Department of Energy’s Office of Science, which is the nation’s single largest supporter of basic research in the physical sciences. Feel the heat at https://energy.gov/science and https://www.pppl.gov.
