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  • richardmitnick 6:02 pm on November 21, 2017 Permalink | Reply
    Tags: , , , , , Fusion technology, , , Plasma-facing material   

    From BNL: “Designing New Metal Alloys Using Engineered Nanostructures” 

    Brookhaven Lab

    Stony Brook University assistant professor Jason Trelewicz brings his research to design and stabilize nanostructures in metals to Brookhaven Lab’s Center for Functional Nanomaterials.

    1
    Materials scientist Jason Trelewicz in an electron microscopy laboratory at Brookhaven’s Center for Functional Nanomaterials, where he characterizes nanoscale structures in metals mixed with other elements.

    Materials science is a field that Jason Trelewicz has been interested in since he was a young child, when his father—an engineer—would bring him to work. In the materials lab at his father’s workplace, Trelewicz would use optical microscopes to zoom in on material surfaces, intrigued by all the distinct features he would see as light interacted with different samples.

    Now, Trelewicz—an assistant professor in the College of Engineering and Applied Sciences’ Department of Materials Science and Chemical Engineering with a joint appointment in the Institute for Advanced Computational Science at Stony Brook University and principal investigator of the Engineered Metallic Nanostructures Laboratory—takes advantage of the much higher magnifications of electron microscopes to see tiny nanostructures in fine detail and learn what happens when they are exposed to heat, radiation, and mechanical forces. In particular, Trelewicz is interested in nanostructured metal alloys (metals mixed with other elements) that incorporate nanometer-sized features into classical materials to enhance their performance. The information collected from electron microscopy studies helps him understand interactions between structural and chemical features at the nanoscale. This understanding can then be employed to tune the properties of materials for use in everything from aerospace and automotive components to consumer electronics and nuclear reactors.

    Since 2012, when he arrived at Stony Brook University, Trelewicz has been using the electron microscopes and the high-performance computing (HPC) cluster at the Center for Functional Nanomaterials (CFN)—a U.S. Department of Energy (DOE) Office of Science User Facility at Brookhaven National Laboratory—to perform his research.

    “At the time, I was looking for ways to apply my idea of stabilizing nanostructures in metals to an application-oriented problem,” said Trelewicz. “I’ve long been interested in nuclear energy technologies, initially reading about fusion in grade school. The idea of recreating the processes responsible for the energy we receive from the sun here on earth was captivating, and fueled my interest in nuclear energy throughout my entire academic career. Though we are still very far away from a fusion reactor that generates power, a large international team on a project under construction in France called ITER is working to demonstrate a prolonged fusion reaction at a large scale.”

    Plasma-facing materials for fusion reactors

    Nuclear fusion—the reaction in which atomic nuclei collide—could provide a nearly unlimited supply of safe, clean energy, like that naturally produced by the sun through fusing hydrogen nuclei into helium atoms. Harnessing this carbon-free energy in reactors requires generating and sustaining a plasma, an ionized gas, at the very high temperatures at which fusion occurs (about six times hotter than the sun’s core) while confining it using magnetic fields. Of the many challenges currently facing fusion reactor demonstrations, one of particular interest to Trelewicz is creating viable materials to build a reactor.

    2
    A model of the ITER tokamak, an experimental machine designed to harness the energy of fusion. A powerful magnetic field is used to confine the plasma, which is held in a doughnut-shaped vessel. Credit: ITER Organization.

    “The formidable materials challenges for fusion are where I saw an opportunity for my research—developing materials that can survive inside the fusion reactor, where the plasma will generate high heat fluxes, high thermal stresses, and high particle and neutron fluxes,” said Trelewicz. “The operational conditions in this environment are among the harshest in which one could expect a material to function.”

    A primary candidate for such “plasma-facing material” is tungsten, because of its high melting point—the highest one among metals in pure form—and low sputtering yield (number of atoms ejected by energetic ions from the plasma). However, tungsten’s stability against recrystallization, oxidation resistance, long-term radiation tolerance, and mechanical performance are problematic.

    Trelewicz thinks that designing tungsten alloys with precisely tailored nanostructures could be a way to overcome these problems. In August, he received a $750,000 five-year award from the DOE’s Early Career Research Program to develop stable nanocrystalline tungsten alloys that can withstand the demanding environment of a fusion reactor. His research is combining simulations that model atomic interactions and experiments involving real-time ion irradiation exposure and mechanical testing to understand the fundamental mechanisms responsible for the alloys’ thermal stability, radiation tolerance and mechanical performance. The insights from this research will inform the design of more resilient alloys for fusion applications.

    In addition to the computational resources they use at their home institution, Trelewicz and his lab group are using the HPC cluster at the CFN—and those at other DOE facilities, such as Titan at Oak Ridge Leadership Computing Facility (a DOE Office of Science User Facility at Oak Ridge National Laboratory)—to conduct large-scale atomistic simulations as part of the project.

    ORNL Cray Titan XK7 Supercomputer

    “The length scales of the structures we want to design into our materials are on the order of a few nanometers to 100 nanometers, and a single simulation can involve up to 10 million atoms,” said Trelewicz. “Using HPC clusters, we can build a system atom-by-atom, representative of the structure we would like to explore experimentally, and run simulations to study the response of that system under various external stimuli. For example, we can fire a high-energy atom into the system and watch what happens to the material and how it evolves, hundreds or thousands of times. Once damage has accumulated in the structure, we can simulate thermal and mechanical forces to understand how defect structure impacts other behavior.”

    These simulations inform the structures and chemistries of experimental alloys, which Trelewicz and his students fabricate at Stony Brook University through high-energy milling. To characterize the nanoscale structure and chemical distribution of the engineered alloys, they extensively use the microscopy facilities at the CFN—including scanning electron microscopes, transmission electron microscopes, and scanning transmission electron microscopes. Imaging is conducted at high resolution and often combined with heating within the microscope to examine in real time how the structures evolve with temperature. Experiments are also conducted at other DOE national labs, such as Sandia through collaboration with materials scientist Khalid Hattar of the Ion Beam Laboratory. Here, students in Trelewicz’s research group simultaneously irradiate the engineered alloys with an ion beam and image them with an electron microscope over the course of many days.

    3
    Trelewicz and his students irradiated a nanostructured tungsten-titanium alloy with high-energy gold ions to explore the radiation tolerance of this novel material.

    “Though this damage does not compare to what the material would experience in a reactor, it provides a starting point to evaluate whether or not the engineered material could indeed address some of the limitations of tungsten for fusion applications,” said Trelewicz.

    Electron microscopy at the CFN has played a key role in an exciting discovery that Trelewicz’s students recently made: an unexpected metastable-to-stable phase transition in thin films of nanostructured tungsten. This phase transition drives an abnormal “grain” growth process in which some crystalline nanostructure features grow very dramatically at the expense of others. When the students added chromium and titanium to tungsten, this metastable phase was completely eliminated, in turn enhancing the thermal stability of the material.

    “One of the great aspects of having both experimental and computational components to our research is that when we learn new things from our experiments, we can go back and tailor the simulations to more accurately reflect the actual materials,” said Trelewicz.

    Other projects in Trelewicz’s research group.

    The research with tungsten is only one of many projects ongoing in the Engineered Metallic Nanostructures Laboratory.

    “All of our projects fall under the umbrella of developing new metal alloys with enhanced and/or multifunctional properties,” said Trelewicz. “We are looking at different strategies to optimize material performance by collectively tailoring chemistry and microstructure in our materials. Much of the science lies in understanding the nanoscale mechanisms that govern the properties we measure at the macroscale.”

    4
    Jason Trelewicz (left) with Olivia Donaldson, who recently graduated with her PhD from Trelewicz’s group, and Jonathan Gentile, a current doctoral student, in front of the scanning electron microscope/focused-ion beam at Stony Brook University’s Advanced Energy Center. Credit: Stony Brook University.

    Through a National Science Foundation CAREER (Faculty Early Career Development Program) award, Trelewicz and his research group are exploring another class of high-strength alloys—amorphous metals, or “metallic glasses,” which are metals that have a disordered atomic structure akin to glass. Compared to everyday metals, metallic glasses are often inherently higher strength but usually very brittle, and it is difficult to make them in large parts such as bulk sheets. Trelewicz’s team is designing interfaces and engineering them into the metallic glasses—initially iron-based and later zirconium-based ones—to enhance the toughness of the materials, and exploring additive manufacturing processes to enable sheet-metal production. They will use the Nanofabrication Facility at the CFN to fabricate thin films of these interface-engineered metallic glasses for in situ analysis using electron microscopy techniques.

    In a similar project, they are seeking to understand how introducing a crystalline phase into a zirconium-based amorphous alloy to form a metallic glass matrix composite (composed of both amorphous and crystalline phases) augments the deformation process relative to that of regular metallic glasses. Metallic glasses usually fail catastrophically because strain becomes localized into shear bands. Introducing crystalline regions in the metallic glasses could inhibit the process by which strain localizes in the material. They have already demonstrated that the presence of the crystalline phase fundamentally alters the mechanism through which the shear bands form.

    Trelewicz and his group are also exploring the deformation behavior of metallic “nanolaminates” that consist of alternating crystalline and amorphous layers, and are trying to approach the theoretical limit of strength in lightweight aluminum alloys through synergistic chemical doping strategies (adding other elements to a material to change its properties).

    5
    Trelewicz and his students perform large-scale atomistic simulations to explore the segregation of solute species to grain boundaries (GBs)—interfaces between grains—in nanostructured alloys, as shown here for an aluminum-magnesium (Al-Mg) system, and its implications for the governing deformation mechanisms. They are using the insights gained through these simulations to design lightweight alloys with theoretical strengths.

    “We leverage resources of the CFN for every project ongoing in my research group,” said Trelewicz. “We extensively use the electron microscopy facilities to look at material micro- and nanostructure, very often at how interfaces are coupled with compositional inhomogeneities—information that helps us stabilize and design interfacial networks in nanostructured metal alloys. Computational modeling and simulation enabled by the HPC clusters at the CFN informs what we do in our experiments.”

    Beyond his work at CFN, Trelewicz collaborates with his departmental colleagues to characterize materials at the National Synchrotron Light Source II—another DOE Office of Science User Facility at Brookhaven.

    BNL NSLS-II


    BNL NSLS II

    “There are various ways to characterize structural and chemical inhomogeneities,” said Trelewicz. “We look at small amounts of material through the electron microscopes at CFN and on more of a bulk level at NSLS-II through techniques such as x-ray diffraction and the micro/nano probe. We combine this local and global information to thoroughly characterize a material and use this information to optimize its properties.”

    Future of next-generation materials

    When he is not doing research, Trelewicz is typically busy with student outreach. He connects with the technology departments at various schools, providing them with materials engineering design projects. The students not only participate in the engineering aspects of materials design but are also trained on how to use 3D printers and other tools that are critical in today’s society to manufacture products more cost effectively and with better performance.

    Going forward, Trelewicz would like to expand his collaborations at the CFN and help establish his research in metallic nanostructures as a core area supported by CFN and, ultimately, DOE, to achieve unprecedented properties in classical materials.

    “Being able to learn something new every day, using that knowledge to have an impact on society, and seeing my students fill gaps in our current understanding are what make my career as a professor so rewarding,” said Trelewicz. “With the resources of Stony Brook University, nearby CFN, and other DOE labs, I have an amazing platform to make contributions to the field of materials science and metallurgy.”

    Trelewicz holds a bachelor’s degree in engineering science from Stony Brook University and a doctorate in materials science and engineering with a concentration in technology innovation from MIT. Before returning to academia in 2012, Trelewicz spent four years in industry managing technology development and transition of harsh-environment sensors produced by additive manufacturing processes. He is the recipient of a 2017 Department of Energy Early Career Research Award, 2016 National Science Foundation CAREER award, and 2015 Young Leaders Professional Development Award from The Minerals, Metals & Materials Society (TMS), and is an active member of several professional organizations, including TMS, the Materials Research Society, and ASM International (the Materials Information Society).

    See the full article here .

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    BNL Campus

    One of ten national laboratories overseen and primarily funded by the Office of Science of the U.S. Department of Energy (DOE), Brookhaven National Laboratory conducts research in the physical, biomedical, and environmental sciences, as well as in energy technologies and national security. Brookhaven Lab also builds and operates major scientific facilities available to university, industry and government researchers. The Laboratory’s almost 3,000 scientists, engineers, and support staff are joined each year by more than 5,000 visiting researchers from around the world. Brookhaven is operated and managed for DOE’s Office of Science by Brookhaven Science Associates, a limited-liability company founded by Stony Brook University, the largest academic user of Laboratory facilities, and Battelle, a nonprofit, applied science and technology organization.
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  • richardmitnick 4:49 am on November 15, 2017 Permalink | Reply
    Tags: Fusion technology, ,   

    From Texas A&M: “Channeling helium: Researchers take next step toward fusion energy” 

    Texas A&M logo

    Texas A&M

    1
    (Plasma Science and Fusion Center) Science Alert

    November 10, 2017
    Lorian Hopcus
    lorian.hopcus@tamu.edu

    1

    Fusion is the process that powers the sun, harnessing it on Earth would provide unlimited clean energy. However, researchers say that constructing a fusion power plant has proven to be a daunting task, in no small part because there have been no materials that could survive the grueling conditions found in the core of a fusion reactor. Now, researchers at Texas A&M University have discovered a way to make materials that may be suitable for use in future fusion reactors.

    The sun makes energy by fusing hydrogen atoms, each with one proton, into helium atoms, which contain two protons. Helium is the byproduct of this reaction. Although it does not threaten the environment, it wreaks havoc upon the materials needed to make a fusion reactor.

    “Helium is an element that we don’t usually think of as being harmful,” said Dr. Michael Demkowicz, associate professor in the Department of Materials Science and Engineering. “It is not toxic and not a greenhouse gas, which is one reason why fusion power is so attractive.”

    However, if you force helium inside of a solid material, it bubbles out, much like carbon dioxide bubbles in carbonated water.

    “Literally, you get these helium bubbles inside of the metal that stay there forever because the metal is solid,” Demkowicz said. “As you accumulate more and more helium, the bubbles start to link up and destroy the entire material.”

    Working with a team of researchers at Los Alamos National Laboratory in New Mexico, Demkowicz investigated how helium behaves in nanocomposite solids, materials made of stacks of thick metal layers. Their findings, recently published in Science Advances, were a surprise. Rather than making bubbles, the helium in these materials formed long channels, resembling veins in living tissues.

    “We were blown away by what we saw,” Demkowicz said. “As you put more and more helium inside these nanocomposites, rather than destroying the material, the veins actually start to interconnect, resulting in kind of a vascular system.”

    This discovery paves the way to helium-resistant materials needed to make fusion energy a reality. Demkowicz and his collaborators believe that helium may move through the networks of veins that form in their nanocomposites, eventually exiting the material without causing any further damage.

    Demkowicz collaborated with Di Chen, Nan Li, Kevin Baldwin and Yongqiang Wang from Los Alamos National Laboratory, as well as former student Dina Yuryev from the Massachusetts Institute of Technology. The project was supported by the Laboratory Directed Research and Development program at Los Alamos National Laboratory.

    “Applications to fusion reactors are just the tip of the iceberg,” Demkowicz said. “I think the bigger picture here is in vascularized solids, ones that are kind of like tissues with vascular networks. What else could be transported through such networks? Perhaps heat or electricity or even chemicals that could help the material self-heal.”

    See the full article here .

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    Located in College Station, Texas, about 90 miles northwest of Houston and within a two to three-hour drive from Austin and Dallas.
    Home to more than 50,000 students, ranking as the sixth-largest university in the country, with more than 370,000 former students worldwide.
    Holds membership in the prestigious Association of American Universities, one of only 62 institutions with this distinction.
    More than $820 million in research expenditures generated by faculty-researchers
    Has an endowment valued at more than $5 billion, which ranks fourth among U.S. public universities and 10th overall.

     
  • richardmitnick 7:42 am on October 17, 2017 Permalink | Reply
    Tags: , Fusion technology, , , , SSEN-steady-state electrical network   

    From PPPL: “PPPL completes shipment of electrical components to power site for ITER, the international fusion experiment” 


    PPPL

    October 16, 2017
    Jeanne Jackson DeVoe

    1
    Electrical components procured by PPPL. Pictured clockwise: switchgear, HV protection and control cubicles, resistors, and insulators. (Photo by Photo courtesy of © ITER Organization, http://www.iter.org/)

    The arrival of six truckloads of electrical supplies at a warehouse for the international ITER fusion experiment on Oct. 2 brings to a successful conclusion a massive project that will provide 120 megawatts of power – enough to light up a small city − to the 445-acre ITER site in France.

    ITER Tokamak in Saint-Paul-lès-Durance, which is in southern France

    The Princeton Plasma Physics Laboratory (PPPL), with assistance from the Department of Energy’s Princeton Site Office, headed the $34 million, five-year project on behalf of US ITER to provide three quarters of the components for the steady-state electrical network (SSEN), which provides electricity for the lights, pumps, computers, heating, ventilation and air conditioning to the huge fusion energy experiment. ITER connected the first transformer to France’s electrical grid in March. The European Union is providing the other 25 percent.

    The shipment was the 35th and final delivery of equipment from companies all over the world, including from the United States over the past three years.

    “I think it’s a great accomplishment to finish this,” said Hutch Neilson, head of ITER Fabrication. “The successful completion of the SSEN program is a very important accomplishment both for the US ITER project and for PPPL as a partner in the US ITER project.”

    The six trucks that arrived carried a total of 63 crates of uninterruptible power supply equipment weighing 107 metric tons. The trucks took a seven-hour, 452-mile journey from Gutor UPS and Power Conversion in Wettingen, Switzerland, northwest of Zurich, to an ITER storage facility in Port-Saint-Louis-Du-Rhône, France. The equipment will eventually be used to provide emergency power to critical ITER systems in the event of a power outage.

    “This represents the culmination of a very complex series of technical specifications and global purchases, and we are grateful to the entire PPPL team and their vendors for outstanding commitment and performance”, said Ned Sauthoff, director of the US ITER Project Office at Oak Ridge National Laboratory, where all U.S. contributions to ITER are managed for the U.S. Department of Energy’s Office of Science.

    A device known as a tokamak, ITER will be the largest and most powerful fusion machine in the world. Designed to produce 500 megawatts of fusion power for 50 megawatts of input power, it will be the first fusion device to create net energy – it will get more energy out than is put in. Fusion is the process by which stars like the sun create energy – the fusing of light elements

    A separate electrical system for the pulsed power electrical network (PPEN), procured by China, will power the ITER tokamak.

    The first SSEN delivery in 2014 was among the first plant components to be delivered to the ITER site. The SSEN project is now one of the first U.S. packages to be completed in its entirety, Neilson said. He noted that the final shipment arrived 10 days ahead of PPPL’s deadline.

    In addition to the electrical components, PPPL is also responsible for seven diagnostic instruments and for integrating the instruments inside ITER port plugs. While PPPL is continuing work on an antenna for one diagnostic, most of the diagnostic and port integration work has been put on hold amid uncertainty over U.S. funding for its contributions to ITER.

    The SSEN project was a complex enterprise. PPPL researched potential suppliers, solicited and accepted bids, and oversaw the production and testing of electrical components in 16 separate packages worth a total of about $30 million. The effort involved PPPL engineers, as well as procurement and quality assurance staff members who worked to make sure that the components met ITER specifications and would do exactly what they are supposed to do. “It’s really important that we deliver to ITER equipment that exactly meets the requirements they specify and that it be quality equipment that doesn’t give them trouble down the road,” Neilson said. “So every member of the team makes sure that gets done.”

    Many of the components were for the high-voltage switchyard. A massive transformer procured by PPPL was connected to the French electrical grid in March. PPPL procured and managed the purchase and transportation of the 87-ton transformer and three others, which were built in South Korea by Hyundai Heavy Industries, a branch of the company known for producing cars. =

    The SSEN components came from as close to home as Mount Pleasant, Pennsylvania, to as far away as Turkey, with other components coming from Mexico, Italy, Spain, France, Germany, South Korea and the Netherlands.

    John Dellas, the head of electrical systems and the team leader for the project, has been working on the ITER SSEN project for the entire five years of the program. He traveled to Schweinfurt, Germany, to oversee testing of the control and protection systems for the high-voltage switchyard.

    Dellas took over the project from Charles Neumeyer after Neumeyer became engineering director for the NSTX-U Recovery Project last year. Dellas said Neumeyer deserves most of the credit for the program. “Charlie took the team down to the 10-yard line and I put everything in the end zone,” Dellas said. “I was working with Charlie but Charlie was the quarterback.”

    Neumeyer worked on the project from 2006, when the project was in the planning stages, until 2016. He said he was happy to see the project completed. “It’s very gratifying to see roughly 10 years of work come to a satisfying conclusion under budget and on schedule,” he said.

    See the full article here .

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    PPPL campus

    Princeton Plasma Physics Laboratory is a U.S. Department of Energy national laboratory managed by Princeton University. PPPL, on Princeton University’s Forrestal Campus in Plainsboro, N.J., is devoted to creating new knowledge about the physics of plasmas — ultra-hot, charged gases — and to developing practical solutions for the creation of fusion energy. Results of PPPL research have ranged from a portable nuclear materials detector for anti-terrorist use to universally employed computer codes for analyzing and predicting the outcome of fusion experiments. The Laboratory is managed by the University for the U.S. Department of Energy’s Office of Science, which is the largest single supporter of basic research in the physical sciences in the United States, and is working to address some of the most pressing challenges of our time. For more information, please visit science.energy.gov.

     
  • richardmitnick 8:51 pm on October 13, 2017 Permalink | Reply
    Tags: 2-D structure of turbulence in tokamaks, , Fusion technology, ,   

    From PPPL: “PPPL takes detailed look at 2-D structure of turbulence in tokamaks” 


    PPPL

    October 13, 2017
    John Greenwald

    1
    Correlation analysis of three plasma discharges on NSTX for each of five different radial locations near the plasma edge. The red regions marked with a blue cross have high positive correlation around the origin point, while the blue regions marked with a yellow cross have high negative correlation. Images courtesy of Stewart Zweben.

    A key hurdle for fusion researchers is understanding turbulence, the ripples and eddies that can cause the superhot plasma that fuels fusion reactions to leak heat and particles and keep fusion from taking place. Comprehending and reducing turbulence will facilitate the development of fusion as a safe, clean and abundant source of energy for generating electricity from power plants around the world.

    At the U.S. Department of Energy’s (DOE) Princeton Plasma Physics Laboratory (PPPL), scientists have assembled a large database of detailed measurements of the two dimensional (2-D) structure of edge plasma turbulence made visible by a diagnostic technique known as gas puff imaging. The two dimensions, measured inside a fusion device called a tokamak, represent the radial and vertical structure of the turbulence.

    Step toward fuller understanding

    “This study is an incremental step toward a fuller understanding of turbulence,” said physicist Stewart Zweben, lead author of the research published in the journal Physics of Plasmas. “It could help us understand how turbulence functions as the main cause of leakage of plasma confinement.”

    Fusion occurs naturally in space, merging the light elements in plasma to release the energy that powers the sun and stars. On Earth, researchers create fusion in facilities like tokamaks, which control the hot plasma with magnetic fields. But turbulence frequently causes heat to leak from its magnetic confinement.

    PPPL scientists have now delved beyond previously published characterizations of turbulence and analyzed the data to focus on the 2-D spatial correlations within the turbulence. This correlation provides clues to the origin of the turbulent behavior that causes heat and particle leakage, and will serve as an additional basis for testing computer simulations of turbulence against empirical evidence.

    Studying 20 discharges of plasma

    The paper studied 20 discharges of plasma chosen as a representative sample of those created in PPPL’s National Spherical Torus Experiment (NSTX) prior to its recent upgrade. In each of these discharges, a gas puff illuminated the turbulence near the edge of the plasma, where turbulence is of special interest. The puffs, a source of neutral atoms that glow in response to density changes within a well-defined region, allowed researchers to see fluctuations in the density of the turbulence. A fast camera recorded the resulting light at the rate of 400,000 frames per second over an image frame size of 64 pixels wide by 80 pixels high.

    Zweben and co-authors performed computational analysis of the data from the camera, determining the correlations between different regions of the frames as the turbulent eddies moved through them. “We’re observing the patterns of the spatial structure,” Zweben said. “You can compare it to the structure of clouds drifting by. Some large clouds can be massed together or there can be a break with just plain sky.”

    Detailed view of turbulence

    The correlations provide a detailed view of the nature of plasma turbulence. “Simple things about turbulence like its size and time scale have long been known,” said PPPL physicist Daren Stotler, a coauthor of the paper. “These simulations take a deep dive into another level to look at how turbulence in one part of the plasma varies with respect to turbulence in another part.”

    In the resulting graphics, a blue cross indicates the point of focus for a calculation; the red and yellow areas around the cross are regions in which the turbulence is evolving similarly to the turbulence at the focal point. Farther away, researchers found regions in which the turbulence is changing opposite to the changes at the focal point. These farther-away regions are shown as shades of blue in the graphics, with the yellow cross indicating the point with the most negative correlation.

    For example, if the red and yellow images were a region of high density turbulence, the blue images indicated low density. “The density increase must come from somewhere,” said Zweben. “Maybe from the blue regions.”

    Going forward, knowledge of these correlations could be used to predict the behavior of turbulence in magnetically confined plasma. Success of the effort could deepen understanding of a fundamental cause of the loss of heat from fusion reactions.

    Also contributing to this study were Filippo Scotti of the Lawrence Livermore National Laboratory and J. R. Myra of Lodestar Research Corporation. Support for this work comes from the DOE Office of Science.

    See the full article here .

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    PPPL campus

    Princeton Plasma Physics Laboratory is a U.S. Department of Energy national laboratory managed by Princeton University. PPPL, on Princeton University’s Forrestal Campus in Plainsboro, N.J., is devoted to creating new knowledge about the physics of plasmas — ultra-hot, charged gases — and to developing practical solutions for the creation of fusion energy. Results of PPPL research have ranged from a portable nuclear materials detector for anti-terrorist use to universally employed computer codes for analyzing and predicting the outcome of fusion experiments. The Laboratory is managed by the University for the U.S. Department of Energy’s Office of Science, which is the largest single supporter of basic research in the physical sciences in the United States, and is working to address some of the most pressing challenges of our time. For more information, please visit science.energy.gov.

     
  • richardmitnick 1:16 pm on October 7, 2017 Permalink | Reply
    Tags: , Fusion technology, , ,   

    From ICL via Science Alert: “We Finally Know The Weird Way Electrons Behave During Fusion-Like Conditions” 

    Imperial College London
    Imperial College London

    Science Alert

    6 OCT 2017
    KARLA LANT

    1
    Imperial College London

    Fusion energy just got one step closer.

    Researchers have at last been able to model the behaviour of electrons under extreme densities and temperatures, similar to those found inside stars and planets.

    Although electrons are ubiquitous in our universe, carrying electrical current and determining the physical properties of materials, physicists have never before been able to describe the ways large numbers of electrons behave together- especially at high densities and temperatures.

    This new research [Physical Review Letters] could shed light on the how matter behaves in fusion experiments, in turn leading to a new source of clean fusion energy.

    Imperial College London Department of Physics Professor Matthew Foulkes told Phys.org:

    “Now, at last, we are in a position to carry out accurate and direct simulations of planetary interiors; solids under intense laser irradiation; laser-activated catalysts; and other warm dense systems.”

    He added, “This is the beginning of a new field of computational science.”

    Although it is easy enough to describe the large-scale behaviours of electrons- such as how electrical current, resistance, and voltage work- quantum forces control the behaviours of electrons at the microscopic level, causing them to act like a quantum mechanical gas.

    Until the success of this research, scientists were only able to create simulations that described the behaviour of this electron gas at very low temperatures.

    However, the centres of planets like Earth and stars are filled with warm, dense matter – matter that is also critical to fusion experiments.

    With the help of computer simulations, the new work solves the equations that describe the electron gas precisely. The team has thus completely described the thermodynamic properties of interacting electrons in warm dense matter for the first time.

    Kiel University Professor of Theoretical Physics Michael Bonitz told Phys.org:

    “These results are the first exact data in this area, and will take our understanding of matter at extreme temperatures to a new level. Amongst other things, the 40-year-old existing models can now be reviewed and improved for the first time.”

    See the full article here .

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    Imperial College London

    Imperial College London is a science-based university with an international reputation for excellence in teaching and research. Consistently rated amongst the world’s best universities, Imperial is committed to developing the next generation of researchers, scientists and academics through collaboration across disciplines. Located in the heart of London, Imperial is a multidisciplinary space for education, research, translation and commercialisation, harnessing science and innovation to tackle global challenges.

     
  • richardmitnick 6:56 pm on September 26, 2017 Permalink | Reply
    Tags: , Fusion technology, ,   

    From PPPL: “Research led by PPPL provides reassurance that heat flux will be manageable in ITER” 


    PPPL

    September 26, 2017
    John Greenwald

    1

    A major issue facing ITER, the international tokamak under construction in France that will be the first magnetic fusion device to produce net energy, is whether the crucial divertor plates that will exhaust waste heat from the device can withstand the high heat flux, or load, that will strike them. Alarming projections extrapolated from existing tokamaks suggest that the heat flux could be so narrow and concentrated as to damage the tungsten divertor plates in the seven-story, 23,000 ton tokamak and require frequent and costly repairs. This flux could be comparable to the heat load experienced by spacecraft re-entering Earth’s atmosphere.

    New findings of an international team led by physicist C.S. Chang of the U.S. Department of Energy’s (DOE) Princeton Plasma Physics Laboratory (PPPL) paint a more positive picture. Results of the collaboration, which has spent two years simulating the heat flux, indicate that the width could be well within the capacity of the divertor plates to tolerate.

    Good news for ITER

    “This could be very good news for ITER,” Chang said of the findings, published in August in the journal Nuclear Fusion. “This indicates that ITER can produce 10 times more power than it consumes, as planned, without damaging the divertor plates prematurely.”

    At ITER, spokesperson Laban Coblentz, said the simulations were of great interest and highly relevant to the ITER project. He said ITER would be keen to see experimental benchmarking, performed for example by the Joint European Torus (JET) at the Culham Centre for Fusion Energy in the United Kingdom, to strengthen confidence in the simulation results.

    Joint European Torus, at the Culham Centre for Fusion Energy in the United Kingdom

    Chang’s team used the highly sophisticated XGC1 plasma turbulence computer simulation code developed at PPPL to create the new estimate. The simulation projected a width of 6 millimeters for the heat flux in ITER when measured in a standardized way among tokamaks, far greater than the less-than 1 millimeter width projected through use of experimental data.

    Deriving projections of narrow width from experimental data were researchers at major worldwide facilities. In the United States, these tokamaks were the National Spherical Torus Experiment before its upgrade at PPPL; the Alcator C-Mod facility at MIT, which ceased operations at the end of 2016; and the DIII-D National Fusion Facility that General Atomics operates for the DOE in San Diego.

    4
    National Spherical Torus Experiment at PPPL

    5
    Alcator C-Mod tokamak at MIT

    6
    DIII-D National Fusion Facility, San Diego

    Widely different conditions

    The discrepancy between the experimental projections and simulation predictions, said Chang, stems from the fact that conditions inside ITER will be too different from those in existing tokamaks for the empirical predictions to be valid. Key differences include the behavior of plasma particles within today’s machines compared with the expected behavior of particles in ITER. For example, while ions contribute significantly to the heat width in the three U.S. machines, turbulent electrons will play a greater role in ITER, rendering extrapolations unreliable.

    Chang’s team used basic physics principles, rather than empirical projections based on the data from existing machines, to derive the simulated wider prediction. The team first tested whether the code could predict the heat flux width produced in experiments on the U.S. tokamaks, and found the predictions to be valid.

    Researchers then used the code to project the width of the heat flux in an estimated model of ITER edge plasma. The simulation predicted the greater heat-flux width that will be sustainable within the current ITER design.

    Supercomputers enabled simulation

    Supercomputers made this simulation possible. Validating the code on the existing tokamaks and producing the findings took some 300 million core hours on Titan and Cori, two of the most powerful U.S. supercomputers, housed at the DOE’s Oak Ridge Leadership Computing Facility and the National Energy Research Scientific Computing Center, respectively.

    ORNL Cray XK7 Titan Supercomputer

    NERSC Cray Cori II supercomputer

    A core hour is one processor, or core, running for one hour.

    Researchers from eight U.S. and European institutions collaborated on this research. In addition to PPPL, the institutions included ITER, the Culham Centre for Fusion Energy, the Institute of Atomic and Subatomic Physics at the Technical University of Vienna, General Atomics, MIT, Oak Ridge National Laboratory and Lawrence Livermore National Laboratory.

    Support for this work comes from the DOE Office of Science Offices of Fusion Energy Sciences and Office of Advanced Scientific Computing Research.

    See the full article here .

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    PPPL campus

    Princeton Plasma Physics Laboratory is a U.S. Department of Energy national laboratory managed by Princeton University. PPPL, on Princeton University’s Forrestal Campus in Plainsboro, N.J., is devoted to creating new knowledge about the physics of plasmas — ultra-hot, charged gases — and to developing practical solutions for the creation of fusion energy. Results of PPPL research have ranged from a portable nuclear materials detector for anti-terrorist use to universally employed computer codes for analyzing and predicting the outcome of fusion experiments. The Laboratory is managed by the University for the U.S. Department of Energy’s Office of Science, which is the largest single supporter of basic research in the physical sciences in the United States, and is working to address some of the most pressing challenges of our time. For more information, please visit science.energy.gov.

     
  • richardmitnick 2:40 pm on September 14, 2017 Permalink | Reply
    Tags: Alfvén eigenmodes, , DIII-D National Fusion Facility, Fusion technology, NOVA and ORBIT simulation codes, ,   

    From PPPL: “Physicists propose new way to stabilize next-generation fusion plasmas” 


    PPPL

    September 11, 2017
    Raphael Rosen

    1
    PPPL physicist Gerrit Kramer.(Photo by Elle Starkman)

    A key issue for next-generation fusion reactors is the possible impact of many unstable Alfvén eigenmodes, wave-like disturbances produced by the fusion reactions that ripple through the plasma in doughnut-shaped fusion facilities called “tokamaks.” Deuterium and tritium fuel react when heated to temperatures near 100 million degrees Celsius, producing high-energy helium ions called alpha particles that heat the plasma and sustain the fusion reactions.

    These alpha particles are even hotter than the fuel and have so much energy that they can drive Alfvén eigenmodes that allow the particles to escape from the reaction chamber before they can heat the plasma. Understanding these waves and how they help alpha particles escape is a key research topic in fusion science.

    If only one or two of these waves are excited in the reaction chamber, the effect on the alpha particles and their ability to heat the fuel is limited. However, theorists have predicted for some time that if many of these waves are excited, they can collectively throw out a lot of alpha particles, endangering the reactor chamber walls and the efficient heating of the fuel.

    Recent experiments conducted on the DIII-D National Fusion Facility, which General Atomics operates for the U.S. Department of Energy (DOE) in San Diego, have revealed evidence that confirms these theoretical predictions.

    1
    DIII-D National Fusion Facility

    3
    https://lasttechage.wordpress.com/2011/07/11/fusion-seawater-and-stewart-pragers-oped/

    Losses of up to 40 percent of high-energy particles are observed in experiments when many Alfvén waves are excited by deuterium beam ions used to simulate alpha particles and higher-energy beam ions in a fusion reactor such as ITER, which is now under construction in the south of France.

    In the wake of this research, physicists at the DOE’s Princeton Plasma Physics Laboratory (PPPL) produced a quantitatively accurate model of the impact of these Alfvén waves on high-energy deuterium beams in the DIII-D tokamak. They used simulation codes called NOVA and ORBIT to predict which Alfvén waves would be excited and their effect on the confinement of the high-energy particles.

    The researchers confirmed the NOVA modeling prediction that over 10 unstable Alfvén waves can be excited by the deuterium beams in the DIII-D experiment. Furthermore, in quantitative agreement with the experimental results, the modeling predicted that up to 40 percent of the energetic particles would be lost. The modeling demonstrated for the first time, in this type of high-performance plasma, that quantitatively accurate predictions can be made for the effect of multiple Alfvén waves on the confinement of energetic particles in the DIII-D tokamak.

    “Our team confirmed that we can quantitatively predict the conditions where the fusion alpha particles can be lost from the plasma based on the results obtained from the modeling of the DIII-D experiments” said Gerrit Kramer, a PPPL research physicist and lead author of a paper that describes the modeling results in the May issue of the journal Nuclear Fusion.

    The joint findings marked a potentially large advance in comprehension of the process. “These results show that we now have a strong understanding of the individual waves excited by the energetic particles and how these waves work together to expel energetic particles from the plasma,” said physicist Raffi Nazikian, head of the ITER and Tokamaks Department at PPPL and leader of the laboratory’s collaboration with DIII-D.

    The NOVA+ORBIT model further indicated that certain plasma conditions could dramatically reduce the number of Alfvén waves and hence lower the energetic-particle losses. Such waves and the losses they produce could be minimized if the electric current profile in the center of the plasma could be broadened, according to the analysis presented in the scientific article.

    Experiments to test these ideas for reducing energetic particle losses will be conducted in a following research campaign on DIII-D. “New upgrades to the DIII-D facility will allow for the exploration of improved plasma conditions,” Nazikian said. “New experiments are proposed to access conditions predicted by the theory to reduce energetic particle losses, with important implications for the optimal design of future reactors.”

    The DOE Office of Science supported this research. Members of the research team contributing to the published article included scientists from PPPL, General Atomics, Lawrence Livermore National Laboratory and the University of California, Irvine.

    See the full article here .

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    PPPL campus

    Princeton Plasma Physics Laboratory is a U.S. Department of Energy national laboratory managed by Princeton University. PPPL, on Princeton University’s Forrestal Campus in Plainsboro, N.J., is devoted to creating new knowledge about the physics of plasmas — ultra-hot, charged gases — and to developing practical solutions for the creation of fusion energy. Results of PPPL research have ranged from a portable nuclear materials detector for anti-terrorist use to universally employed computer codes for analyzing and predicting the outcome of fusion experiments. The Laboratory is managed by the University for the U.S. Department of Energy’s Office of Science, which is the largest single supporter of basic research in the physical sciences in the United States, and is working to address some of the most pressing challenges of our time. For more information, please visit science.energy.gov.

     
  • richardmitnick 1:05 pm on September 11, 2017 Permalink | Reply
    Tags: Fusion technology, , NSTX-U Tokamak at PPPL,   

    From PPPL: “PPPL has a new interim director and is moving ahead with construction of prototype magnets” 


    PPPL

    September 8, 2017
    Jeanne Jackson DeVoe

    1
    Rich Hawryluk (Photo by Elle Starkman )

    Rich Hawryluk has been appointed interim director of the U.S. Department of Energy’s (DOE) Princeton Plasma Physics Laboratory (PPPL) while an international search for a permanent director moves forward, Princeton University Vice President for PPPL David McComas announced recently. Hawryluk, who has been heading the NSTX-U Recovery Project, is an internationally-known physicist and a former deputy director of PPPL.

    PPPL NSTX-U

    “Rich has earned my highest respect and the respect of his colleagues and staff at PPPL and of researchers throughout the world for his work as a scientist, project manager, and leader. I am delighted he has agreed to head the Laboratory as we move into the next phase of the NSTX-U recovery,” McComas said.

    Hawryluk said that he was grateful for the opportunity to lead the Laboratory where he has worked for more than four decades. “I feel deeply about this place,” he said. “It has given me enormous opportunities to do research, as well as scientific and technical management. I feel it’s incumbent on me to do all I possibly can to give the scientists and the engineers and the staff here exciting and productive scientific opportunities both in the near future as well for the long term.”

    Terry Brog, who served as interim director since September 2016, will return to his previous position as deputy director for operations and chief operating officer that he assumed in June of 2016. Stacia Zelick, who served as interim deputy director for operations under Brog, will continue to serve in a leadership role. Michael Zarnstorff, the deputy director for research, will remain in his position. Physicists Jon Menard, head of NSTX-U research and Stefan Gerhardt, deputy engineering director for the project, will now lead the NSTX-U Recovery Project. Charles Neumeyer will remain as the NSTX-U Recovery Project engineering director and deputy head of engineering for NSTX-U.

    The leadership change comes as PPPL moves ahead with constructing prototype magnets in preparation for replacing the one that failed last year and five others that were built under similar conditions.

    Construction of the first prototype magnet follows a comprehensive review of each system of NSTX-U by a team of engineers and scientists from PPPL as well as nearly 50 external experts from the United States and around the world.

    “For the Laboratory to succeed, we must utilize the talents, creativity and skills of all of the staff,” Hawryluk said. “My job is to enable other people to address the issues facing the Laboratory and to set a firm foundation for the future director.”

    Hawryluk and McComas both thanked Brog and Zelick for their leadership during the past several months. “I’m extremely grateful for all the work that Terry and Stacia have done in their respective roles over the last year,” McComas said. Hawryluk also noted that it was his pleasure to work with the NSTX-U team and, in particular, Charlie Neumeyer, Stefan Gerhardt and Jon Menard who “are very dedicated to bringing NSTX-U back on line.”

    The new interim director has been at PPPL for most of his career. He came to PPPL in 1974 after receiving a Ph.D. in physics from MIT. He headed the Tokamak Fusion Test Reactor, then the largest magnetic confinement fusion facility in the United States, from 1991 to 1997. Hawryluk oversaw all research and technical operations as deputy director of the Laboratory for 11 years from 1997 to 2008. He was then head of PPPL’s ITER and Tokamaks Department from 2009 to 2011. From 2011 to 2013, Hawryluk worked at ITER in France, serving as the deputy director-general for the Administration Department of ITER.

    ITER Tokamak in Saint-Paul-lès-Durance, which is in southern France

    In 2013, Hawryluk returned to the Laboratory as head of the ITER and Tokamaks department. He remained in that position until he became head of the Recovery Project last year. Hawryluk has received numerous awards during his career including a Department of Energy Distinguished Associate Award, a Kaul Foundation Prize for Excellence in Plasma Physics Research and Technology, a Fusion Power Award, and an American Physical Society Prize for Excellence in Plasma Physicswith physicists Rob Goldston and James Strachan. A fellow of the American Association for the Advancement of Science since 2008 and of the American Physical Society since 1986, he also chairs the board of editors of Nuclear Fusion, a monthly journal devoted to controlled fusion energy.

    Hawryluk and his wife Mary Katherine Hawryluk, a school psychologist working with special needs children at the New Road School in Parlin, New Jersey, met as undergraduates and have been married for 41 years. They have two grown sons: Kevin, who lives in Chicago, and David, who lives in Los Angeles. In his spare time, Hawryluk is an avid reader.

    “I’m taking on this task because I really believe in PPPL and its critical role in furthering the field of plasma physics with the goal of developing fusion energy,” Hawryluk said. “I am committed to addressing issues that are central to the long-term success of the Laboratory.”

    See the full article here .

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    PPPL campus

    Princeton Plasma Physics Laboratory is a U.S. Department of Energy national laboratory managed by Princeton University. PPPL, on Princeton University’s Forrestal Campus in Plainsboro, N.J., is devoted to creating new knowledge about the physics of plasmas — ultra-hot, charged gases — and to developing practical solutions for the creation of fusion energy. Results of PPPL research have ranged from a portable nuclear materials detector for anti-terrorist use to universally employed computer codes for analyzing and predicting the outcome of fusion experiments. The Laboratory is managed by the University for the U.S. Department of Energy’s Office of Science, which is the largest single supporter of basic research in the physical sciences in the United States, and is working to address some of the most pressing challenges of our time. For more information, please visit science.energy.gov.

     
  • richardmitnick 1:31 pm on August 28, 2017 Permalink | Reply
    Tags: , Fusion technology, , ,   

    From PPPL: “PPPL physicists essential to new campaign on world’s most powerful stellarator” 


    PPPL

    August 28, 2017
    John Greenwald

    KIT Wendelstein 7-X, built in Greifswald, Germany

    1
    Fish-eye view of interior of W7-X showing graphite tiles that cover magnetic coils. (Photo courtesy of IPP.)

    Physicists from the U.S. Department of Energy’s (DOE) Princeton Plasma Physics Laboratory (PPPL) are providing critical expertise for the first full campaign of the world’s largest and most powerful stellarator, a magnetic confinement fusion experiment, the Wendelstein 7-X (W7-X) in Germany. The fusion facility resumes operating on August 28, 2017, and will investigate the suitability of its optimized magnetic fields to create steady state plasmas and to serve as a model for a future power plant for the production of a “star in a jar,” a virtually limitless source of safe and clean energy for generating electricity.

    The W7-X started up in December, 2015, and concluded its initial run in March, 2016. The facility has since been upgraded to prepare for the high-power campaign that is set to begin.

    Deeply involved in the new 15-week run are PPPL physicists Sam Lazerson and Novimir Pablant, who are spending two years at the Max Planck Institute of Plasma Physics in Greifswald, Germany. Lazerson, who previously mapped the W7-X magnetic fields with barn-door sized magnetic coils built by PPPL, heads a task force that will plan and run a series of experiments on the stellarator. Pablant, who designed an x-ray crystal spectrometer to record the behavior of W7-X plasma, will operate the diagnostic together with a German spectrometer and will contribute to planning and executing research.

    First run in designed configuration

    “This will be the first run of the machine in its designed configuration,” said David Gates, who heads the stellarator physics division at PPPL and oversees the laboratory’s role as lead U.S. collaborator in the W7-X project. The new run will test a device called an “island divertor” for exhausting thermal energy and impurities. The campaign will also increase the heating power of the stellarator to eight megawatts to enable operation at a higher beta — the ratio of plasma pressure to the magnetic field pressure, a key factor for plasma confinement.

    Such progress marks steps toward lengthening the confinement time of the hot, charged plasma gas that fuels fusion reactions within the optimized machine. “The goal is to increase plasma confinement compared with traditional stellarators,” said Gates.

    Going forward, Max Planck engineers plan to install a U.S.-built “scraper element” on the W7-X after completion of the initial 15-week campaign. The following phase will study the ability of the unit, originally designed at Oak Ridge National Laboratory and completed at PPPL, to intercept heat flowing toward the divertor and improve its performance. Plans call next for installation of a water-cooled divertor in 2019 to further increase the allowable pulse length of the stellarator.

    See the full article here .

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    PPPL campus

    Princeton Plasma Physics Laboratory is a U.S. Department of Energy national laboratory managed by Princeton University. PPPL, on Princeton University’s Forrestal Campus in Plainsboro, N.J., is devoted to creating new knowledge about the physics of plasmas — ultra-hot, charged gases — and to developing practical solutions for the creation of fusion energy. Results of PPPL research have ranged from a portable nuclear materials detector for anti-terrorist use to universally employed computer codes for analyzing and predicting the outcome of fusion experiments. The Laboratory is managed by the University for the U.S. Department of Energy’s Office of Science, which is the largest single supporter of basic research in the physical sciences in the United States, and is working to address some of the most pressing challenges of our time. For more information, please visit science.energy.gov.

     
  • richardmitnick 11:05 am on August 22, 2017 Permalink | Reply
    Tags: Alcator C-Mod tokamak at MIT, Fusion technology, , UK’s Joint European Torus (JET) Europe’s largest fusion device,   

    From MIT: “Fusion heating gets a boost” 

    MIT News

    MIT Widget

    MIT News

    August 21, 2017
    Paul Rivenberg | Plasma Science and Fusion Center

    1
    The interior of the Alcator C-Mod tokamak, where experiments were conducted that have helped create a new scenario for heating plasma and achieving fusion. Photo: Bob Mumgaard/Plasma Science and Fusion Center

    In the quest for fusion energy, scientists have spent decades experimenting with ways to make plasma fuel hot and dense enough to generate significant fusion power. At MIT, researchers have focused their attention on using radio-frequency (RF) heating in magnetic confinement fusion experiments like the Alcator C-Mod tokamak, which completed its final run in September 2016.

    Now, using data from C-Mod experiments, fusion researchers at MIT’s Plasma Science and Fusion Center (PSFC), along with colleagues in Belgium and the UK, have created a new method of heating fusion plasmas in tokamaks. The new method has resulted in raising trace amounts of ions to megaelectronvolt (MeV) energies — an order of magnitude greater than previously achieved.

    “These higher energy ranges are in the same range as activated fusion products,” PSFC research scientist John C. Wright explains. “To be able to create such energetic ions in a non-activated device — not doing a huge amount of fusion — is beneficial, because we can study how ions with energies comparable to fusion reaction products behave, how well they would be confined.”

    The new approach, recently detailed in the journal Nature Physics, uses a fuel composed of three ion species hydrogen, deuterium, and trace amounts (less than 1 percent) of helium-3. Typically, plasma used for fusion research in the laboratory would be composed of two ion species, deuterium and hydrogen or deuterium and He-3, with deuterium dominating the mixture by up to 95 percent. Researchers focus energy on the minority species, which heats up to much higher energies owing to its smaller fraction of the total density. In the new three-species scheme, all the RF energy is absorbed by just a trace amount of He-3 and the ion energy is boosted even more — to the range of activated fusion products.

    Wright was inspired to pursue this research after attending a lecture in 2015 on this scenario by Yevgen Kasakov, a researcher at the Laboratory for Plasma Physics in Brussels, Belgium, and the lead author of the Nature Physics article. Wright suggested that MIT test these ideas using Alcator C-Mod, with Kasakov and his colleague Jef Ongena collaborating from Brussels.

    At MIT, PSFC research scientist Stephen Wukitch helped developed the scenario and run the experiment, while Professor Miklos Porkolab contributed his expertise on RF heating. Research scientist Yijun Lin was able to measure the complex wave structure in the plasma with the PSFC’s unique phase contrast imaging (PCI) diagnostic, which was developed over the last two decades by Porkolab and his graduate students. Research scientist Ted Golfinopoulos supported the experiment by tracking the effect of MeV-range ions on measurements of plasma fluctuations.

    The successful results on C-Mod provided proof of principle, enough to get scientists at the UK’s Joint European Torus (JET), Europe’s largest fusion device, interested in reproducing the results.

    3
    UK’s Joint European Torus (JET), Europe’s largest fusion device

    “The JET folks had really good energetic particle diagnostics, so they could directly measure these high energy ions and verify that they were indeed there,” he says. “The fact that we had a basic theory realized on two different devices on two continents came together to produce a strong paper.”

    Porkolab suggests that the new approach could be helpful for MIT’s collaboration with the Wendelstein 7-X stellarator at the Max Planck Institute for Plasma Physics in Greifswald, Germany, where research is ongoing on one of the fundamental physics questions: How well fusion-relevant energetic ions are confined.

    KIT Wendelstein 7-X, built in Greifswald, Germany

    The Nature Physics article also notes that the experiments could provide insight into the abundant flux of He-3 ions observed in solar flares.

    Like JET, C-Mod operated at magnetic field strength and plasma pressure comparable to what would be needed in a future fusion-capable device. The two tokamaks also had complementary diagnostic capabilities, making it possible for C-Mod to measure the waves involved in the complex wave-particle interaction, while JET was able to directly measure the MeV-range particles.

    See the full article here .

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    The mission of MIT is to advance knowledge and educate students in science, technology, and other areas of scholarship that will best serve the nation and the world in the twenty-first century. We seek to develop in each member of the MIT community the ability and passion to work wisely, creatively, and effectively for the betterment of humankind.

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