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  • richardmitnick 10:33 am on May 27, 2020 Permalink | Reply
    Tags: "Return of the Blob: Scientists find surprising link to troublesome turbulence at the edge of fusion plasmas", Blobs can wreak havoc in plasma required for fusion reactions., , NSTX-U Tokamak at PPPL,   

    From PPPL: “Return of the Blob: Scientists find surprising link to troublesome turbulence at the edge of fusion plasmas” 


    From PPPL

    May 26, 2020
    John Greenwald

    1
    Image showing spiraling magnetic field fluctuations at the edge of the NSTX tokamak. (Photo courtesy of Physics of Plasmas. Composition by Elle Starkman/Office of Communications.)

    PPPL NSTX -U at Princeton Plasma Physics Lab, Princeton, NJ,USA

    Blobs can wreak havoc in plasma required for fusion reactions. This bubble-like turbulence swells up at the edge of fusion plasmas and drains heat from the edge, limiting the efficiency of fusion reactions in doughnut-shaped fusion facilities called “tokamaks.” Researchers at the U.S. Department of Energy’s (DOE) Princeton Plasma Physics Laboratory (PPPL) have now discovered a surprising correlation of the blobs with fluctuations of the magnetic field that confines the plasma fueling fusion reactions in the device core.

    New aspect of understanding

    Further investigation of this correlation and its role in the loss of heat from magnetic fusion reactors will help to produce on Earth the fusion energy that powers the sun and stars. “These results add a new aspect to our understanding of the plasma edge heat loss in a tokamak,” said physicist Stewart Zweben, lead author of a paper (link is external) in Physics of Plasmas that editors have selected as a featured article. “This work also contributes to our understanding of the physics of blobs, which can help to predict the performance of tokamak fusion reactors.”

    Fusion reactions combine light elements in the form of plasma — the hot, charged state of matter composed of free electrons and atomic nuclei that makes up 99 percent of the visible universe — to produce massive amounts of energy. Scientists are seeking to create and control fusion on Earth as a source of safe, clean and virtually limitless power to generate electricity.

    PPPL researchers discovered the surprising link last year when re-analyzing experiments made in 2010 on PPPL’s National Spherical Torus Experiment (NSTX) — the forerunner of today’s National Spherical Torus Experiment-Upgrade (NSTX-U). The blobs and fluctuations in the magnetic field, called “magnetohydrodynamic (MHD)” activity, develop in all tokamaks and have traditionally been seen as independent of each other.

    Surprise clue

    The first clue to the correlation was the striking regularity of the trajectory of large blobs, which travel at roughly the speed of a rifle bullet, in experiments analyzed in 2015 and 2016. Such blobs normally move randomly in what is called the “scrape-off layer” at the edge of tokamak plasma, but in some cases all large blobstraveled at nearly the same angle and speed. Moreover, the time between the appearance of each large blob at the edge of the plasma was nearly always the same, virtually coinciding with the frequency of dominant MHD activity in the plasma edge.

    Researchers then tracked the diagnostic signals of the blobs and the MHD activity in relation to each other to measure what is called the “cross-correlation coefficient,” which they used to evaluate a set of the 2010 NSTX experiments. Roughly 10 percent of those experiments were found to show a significant correlation between the two variables.

    The scientists then analyzed several possible causes of the correlation, but could find no single compelling explanation. To understand and control this phenomenon, Zweben said, further data analysis and modeling will have to be done — perhaps by readers of the Physics of Plasmas paper.

    Support for this work comes from the DOE Office of Science, with portions of the research performed under the auspices of Lawrence Livermore National Laboratory.

    See the full article here .


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    Please help promote STEM in your local schools.

    Stem Education Coalition


    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.http://www.energy.gov.

    Princeton University campus

     
  • richardmitnick 1:05 pm on September 11, 2017 Permalink | Reply
    Tags: , , 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 .

    Please help promote STEM in your local schools.

    STEM Icon

    Stem Education Coalition


    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.

     
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