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  • richardmitnick 7:39 am on April 1, 2017 Permalink | Reply
    Tags: , MPIPP, PPPL   

    From PPPL and Max Planck Institute of Plasma Physics via phys.org: “Physicists reveal experimental verification of a key source of fast reconnection of magnetic fields” 


    PPPL

    MPIPP bloc

    Max Planck Institute for Plasma Physics

    March 31, 2017

    1
    Physicist Will Fox with Magnetic Reconnection Experiment. Credit: Elle Starkman/PPPL Office of Communications

    Magnetic reconnection, a universal process that triggers solar flares and northern lights and can disrupt cell phone service and fusion experiments, occurs much faster than theory says that it should. Now researchers at the U.S. Department of Energy’s (DOE) Princeton Plasma Physics Laboratory (PPPL) and Germany’s Max Planck Institute of Plasma Physics have discovered a source of the speed-up in a common form of reconnection. Their findings could lead to more accurate predictions of damaging space weather and improved fusion experiments.

    Reconnection occurs when the magnetic field lines in plasma—the collection of atoms and charged electrons and atomic nuclei, or ions, that make up 99 percent of the visible universe—converge and forcefully snap apart. Electrons that exert a varying degree of pressure form an important part of this process as reconnection takes place.

    The research team found that variation in the electron pressure develops along the magnetic field lines in the region undergoing reconnection. This variation balances and keeps a strong electric current inside the plasma from growing out of control and halting the reconnection process. It is this balancing act that makes possible fast reconnection.

    “The main issue we addressed is how reconnection can take place so quickly,” said Will Fox, lead author of a paper that detailed the findings in March in the journal Physical Review Letters. “Here we’ve shown experimentally how electron pressure accelerates the process.”

    The physics team built a picture of the gradient and other parameters of reconnection from research conducted on the Magnetic Reconnection Experiment (MRX) at PPPL, the leading laboratory device for studying reconnection. The findings marked the first experimental confirmation of predictions made by earlier simulations performed by other researchers of the behavior of ions and electrons during reconnection. “The experiments demonstrate how the plasma can sustain a large electric field while preventing a large electric current from building up and halting the reconnection process,” said Fox.

    Among potential applications of the results:

    Predictions of space storms. Magnetic reconnection in the magnetosphere, the magnetic field that surrounds the Earth, can set off geomagnetic “substorms” that disable communications and global positioning satellites (GPS) and disrupt electrical grids. Improved understanding of fast reconnection can help locate regions where the process triggering storms is ready to take place.
    Mitigation of the impact. Advanced warning of reconnection and the disruptions that may follow can lead to steps to protect sensitive satellite systems and electric grids.
    Improvement of fusion facility performance. The process observed in MRX likely plays a key role in producing what are called “sawtooth” instabilities that can halt fusion reactions. Understanding the process could open the door to controlling it and limiting such instabilities. “How sawtooth happens so fast has been a mystery that this research helps to explain,” said Fox. “In fact, it was computer simulations of sawtooth crashes that first linked electron pressure to the source of fast reconnection.”

    See the full article here .

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    MPIPP campus

    The Max Planck Institute of Plasma Physics (Max-Planck-Institut für Plasmaphysik, IPP) is a physics institute for the investigation of plasma physics, with the aim of working towards fusion power. The institute also works on surface physics, also with focus on problems of fusion power.

    The IPP is an institute of the Max Planck Society, part of the European Atomic Energy Community, and an associated member of the Helmholtz Association.

    The IPP has two sites: Garching near Munich (founded 1960) and Greifswald (founded 1994), both in Germany.

    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 11:18 am on December 22, 2016 Permalink | Reply
    Tags: A better way to simulate accretion of the supermassive black hole at the center of the Milky Way is developed by PPPL and Princeton scientists, , Kinetic approach, Pegasus computer code, PPPL,   

    From PPPL: “A better way to simulate accretion of the supermassive black hole at the center of the Milky Way is developed by PPPL and Princeton scientists” 


    PPPL

    December 22, 2016
    John Greenwald

    1
    Image and inset of region surrounding Sagittarius A*. (Image: NASA/UMass/D.Wang et al. Inset: NASA/STScI)

    Scientists at Princeton University and the U.S. Department of Energy’s (DOE) Princeton Plasma Physics Laboratory (PPPL) have developed a rigorous new method for modeling the accretion disk that feeds the supermassive black hole at the center of our Milky Way galaxy.

    Sag A*  NASA Chandra X-Ray Observatory 23 July 2014, the supermassive black hole at the center of the Milky Way
    Sag A* NASA Chandra X-Ray Observatory 23 July 2014, the supermassive black hole at the center of the Milky Way

    The paper, published online in December in the journal Physical Review Letters, provides a much-needed foundation for simulation of the extraordinary processes involved.

    Accretion disks are clouds of plasma that orbit and gradually swirl into massive bodies such as black holes — intense gravitational fields produced by stars that collapse to a tiny fraction of their original size. These collapsed stars are bounded by an “event horizon,” from which not even light can escape. As accretion disks flow toward event horizons, they power some of the brightest and most energetic sources of electromagnetic radiation in the universe.

    Four million times the mass of the sun

    The colossal black hole at the center of the Milky Way — called “Sagittarius A*” because it is found in the constellation Sagittarius — has a gravitational mass that is four million times greater than our own sun. Yet the accretion disk plasma that spirals into this mass is “radiatively inefficient,” meaning that it emits much less radiation than one would expect.

    “So the question is, why is this disk so quiescent?” asks Matthew Kunz, lead author of the paper, assistant professor of astrophysical sciences at Princeton University and a physicist at PPPL. Co-authors include James Stone, Princeton professor of astrophysical sciences, and Eliot Quataert, director of theoretical astrophysics at the University of California, Berkeley.

    To develop a method for finding the answer, the researchers considered the nature of the superhot Sagittarius A* accretion disk. Its plasma is so hot and dilute that it is collisionless, meaning that the trajectories of protons and electrons inside the plasma rarely intersect.

    This lack of collisionality distinguishes the Sagittarius A* accretion disk from brighter and more radiative disks that orbit other black holes. The brighter disks are collisional and can be modeled by formulas dating from the 1990s, which treat the plasma as an electrically conducting fluid. But “such models are inappropriate for accretion onto our supermassive black hole,” Kunz said, since they cannot describe the process that causes the collisionless Sagittarius A* disk to grow unstable and spiral down.

    Tracing collisionless particles

    To model the process for the Sagittarius A* disk, the paper replaces the formulas that treat the motion of collisional plasmas as a macroscopic fluid. Instead, the authors use a method that physicists call “kinetic” to systematically trace the paths of individual collisionless particles. This complex approach, conducted using the Pegasus computer code developed at Princeton by Kunz, Stone and Xuening Bai, now a lecturer at Harvard University, produced a set of equations better able to model behavior of the disk that orbits the supermassive black hole.

    This kinetic approach could help astrophysicists understand what causes the accretion disk region around the Sagittarius A* hole to radiate so little light. Results could also improve understanding of other key issues, such as how magnetized plasmas behave in extreme environments and how magnetic fields can be amplified.

    The goal of the new method, said Kunz, “will be to produce more predictive models of the emission from black-hole accretion at the galactic center for comparison with astrophysical observations.” Such observations come from instruments such as the Chandra X-ray observatory, an Earth-orbiting satellite that NASA launched in 1999, and the upcoming Event Horizon Telescope, an array of nine Earth-based radio telescopes located in countries around the world.

    NASA/Chandra Telescope
    NASA/Chandra Telescope

    Event Horizon Telescope Array

    Event Horizon Telescope map

    The locations of the radio dishes that will be part of the Event Horizon Telescope array. Image credit: Event Horizon Telescope sites, via University of Arizona at https://www.as.arizona.edu/event-horizon-telescope.

    Arizona Radio Observatory
    Arizona Radio Observatory/Submillimeter-wave Astronomy (ARO/SMT)

    ESO/APEX
    Atacama Pathfinder EXperiment (APEX)

    CARMA Array no longer in service
    Combined Array for Research in Millimeter-wave Astronomy (CARMA)

    Atacama Submillimeter Telescope Experiment (ASTE)
    Atacama Submillimeter Telescope Experiment (ASTE)

    Caltech Submillimeter Observatory
    Caltech Submillimeter Observatory (CSO)

    IRAM NOEMA interferometer
    Institut de Radioastronomie Millimetrique (IRAM) 30m

    James Clerk Maxwell Telescope interior, Mauna Kea, Hawaii, USA
    James Clerk Maxwell Telescope interior, Mauna Kea, Hawaii, USA

    Large Millimeter Telescope Alfonso Serrano
    Large Millimeter Telescope Alfonso Serrano

    CfA Submillimeter Array Hawaii SAO
    Submillimeter Array Hawaii SAO

    Future Array/Telescopes

    ESO/NRAO/NAOJ ALMA Array
    ESO/NRAO/NAOJ ALMA Array, Chile

    Plateau de Bure interferometer
    Plateau de Bure interferometer

    South Pole Telescope SPTPOL
    South Pole Telescope SPTPOL

    Research for this paper was funded by the National Science Foundation and grants from the Lyman Spitzer, Jr. Fellowship; a Simons Investigator Award from the Simons Foundation; and the David and Lucille Packard Foundation.

    See the full article here .

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    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 10:09 am on December 12, 2016 Permalink | Reply
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    From PPPL: “PPPL physicists win funding to lead a DOE exascale computing project” 


    PPPL

    October 27, 2016 [Just now out on social media.]
    Raphael Rosen

    1
    PPPL physicist Amitava Bhattacharjee. (Photo by Elle Starkman/PPPL Office of Communications)

    A proposal from scientists at the U.S. Department of Energy’s (DOE) Princeton Plasma Physics Laboratory (PPPL) has been chosen as part of a national initiative to develop the next generation of supercomputers. Known as the Exascale Computing Project (ECP), the initiative will include a focus on exascale-related software, applications, and workforce training.

    Once developed, exascale computers will perform a billion billion operations per second, a rate 50 to 100 times faster than the most powerful U.S. computers now in use. The fastest computers today operate at the petascale and can perform a million billion operations per second. Exascale machines in the United States are expected to be ready in 2023.

    The PPPL-led multi-institutional project, titled High-Fidelity Whole Device Modeling of Magnetically Confined Fusion Plasmas, was selected during the ECP’s first round of application development funding, which distributed $39.8 million. The overall project will receive $2.5 million a year for four years to be distributed among all the partner institutions, including Argonne, Lawrence Livermore, and Oak Ridge national laboratories, together with Rutgers University, the University of California, Los Angeles, and the University of Colorado, Boulder. PPPL itself will receive $800,000 per year; the project it leads was one of 15 selected for full funding, and the only one dedicated to fusion energy. Seven additional projects received seed funding.

    The application efforts will help guide DOE’s development of a U.S. exascale ecosystem as part of President Obama’s National Strategic Computing Initiative (NSCI). DOE, the Department of Defense and the National Science Foundation have been designated as NSCI lead agencies, and ECP is the primary DOE contribution to the initiative.

    The ECP’s multi-year mission is to maximize the benefits of high performance computing (HPC) for U.S. economic competitiveness, national security and scientific discovery. In addition to applications, the DOE project addresses hardware, software, platforms and workforce development needs critical to the effective development and deployment of future exascale systems. The ECP is supported jointly by DOE’s Office of Science and the National Nuclear Security Administration within DOE.

    PPPL has been involved with high-performance computing for years. PPPL scientists created the XGC code, which models the behavior of plasma in the boundary region where the plasma’s ions and electrons interact with each other and with neutral particles produced by the tokamak’s inner wall. The high-performance code is maintained and updated by PPPL scientist C.S. Chang and his team.

    3
    PPPL scientist C.S. Chang

    XGC runs on Titan, the fastest computer in the United States, at the Oak Ridge Leadership Computing Facility, a DOE Office of Science User Facility at Oak Ridge National Laboratory.

    ORNL Cray Titan Supercomputer
    ORNL Cray Titan Supercomputer

    The calculations needed to model the behavior of the plasma edge are so complex that the code uses 90 percent of the computer’s processing capabilities. Titan performs at the petascale, completing a million billion calculations each second, and the DOE was primarily interested in proposals by institutions that possess petascale-ready codes that can be upgraded for exascale computers.

    The PPPL proposal lays out a four-year plan to combine XGC with GENE, a computer code that simulates the behavior of the plasma core. GENE is maintained by Frank Jenko, a professor at the University of California, Los Angeles. Combining the codes would give physicists a far better sense of how the core plasma interacts with the edge plasma at a fundamental kinetic level, giving a comprehensive view of the entire plasma volume.

    Leading the overall PPPL proposal is Amitava Bhattacharjee, head of the Theory Department at PPPL. Co-principal investigators are PPPL’s Chang and Andrew Siegel, a computational scientist at the University of Chicago.

    The multi-institutional effort will develop a full-scale computer simulation of fusion plasma. Unlike current simulations, which model only part of the hot, charged gas, the proposed simulations will display the physics of an entire plasma all at once. The completed model will integrate the XGC and GENE codes and will be designed to run on exascale computers.

    The modeling will enable physicists to understand plasmas more fully, allowing them to predict its behavior within doughnut-shaped fusion facilities known as tokamaks. The exascale computing fusion proposal focuses primarily on ITER, the international tokamak being built in France to demonstrate the feasibility of fusion power.

    Iter experimental tokamak nuclear fusion reactor that is being built next to the Cadarache facility in Saint Paul les-Durance south of France
    Iter experimental tokamak nuclear fusion reactor that is being built next to the Cadarache facility in Saint Paul les-Durance south of France

    But the proposal will be developed with other applications in mind, including stellarators, another variety of fusion facility.

    Wendelstgein 7-X stellarator
    Wendelstgein 7-X stellarator,built in Greifswald, Germany

    Better predictions can lead to better engineered facilities and more efficient fusion reactors. Currently, support for this work comes from the DOE’s Advanced Science Computing Research program.

    “This will be a team effort involving multiple institutions,” said Bhattacharjee. He noted that PPPL will be involved in every aspect of the project, including working with applied mathematicians and computer scientists on the team to develop the simulation framework that will couple GENE with XGC on exascale computers.

    “You need a very-large-scale computer to calculate the multiscale interactions in fusion plasmas,” said Chang. “Whole-device modeling is about simulating the whole thing: all the systems together.”

    Because plasma behavior is immensely complicated, developing an exascale computer is crucial for future research. “Taking into account all the physics in a fusion plasma requires enormous computational resources,” said Bhattacharjee. “With the computer codes we have now, we are already pushing on the edge of the petascale. The exascale is very much needed in order for us to have greater realism and truly predictive capability.”

    See the full article here .

    Please help promote STEM in your local schools.

    STEM Icon

    Stem Education Coalition

    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 7:14 am on December 3, 2016 Permalink | Reply
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    From PPPL: “PPPL and Max Planck physicists confirm the precision of magnetic fields in the most advanced stellarator in the world” 


    PPPL

    December 2, 2016
    John Greenwald

    Physicist Sam Lazerson of the U.S. Department of Energy’s (DOE) Princeton Plasma Physics Laboratory (PPPL) has teamed with German scientists to confirm that the Wendelstein 7-X (W7-X) fusion energy device called a stellarator in Greifswald, Germany, produces high-quality magnetic fields that are consistent with their complex design.

    PPPL Wendelstein 7-X, built in Greifswald, Germany
    Wendelstein 7-X, built in Greifswald, Germany

    The findings, published in the November 30 issue of Nature Communications, revealed an error field — or deviation from the designed configuration — of less than one part in 100,000. Such results could become a key step toward verifying the feasibility of stellarators as models for future fusion reactors.

    W7-X, for which PPPL is the leading U.S. collaborator, is the largest and most sophisticated stellarator in the world. Built by the Max Planck Institute for Plasma Physics in Greifswald, it was completed in 2015 as the vanguard of the stellarator design. Other collaborators on the U.S. team include DOE’s Oak Ridge and Los Alamos National Laboratories, along with Auburn University, the Massachusetts Institute of Technology, the University of Wisconsin-Madison and Xanthos Technologies.

    Twisty magnetic fields

    Stellarators confine the hot, charged gas, otherwise known as plasma, that fuels fusion reactions in twisty — or 3D — magnetic fields, compared with the symmetrical — or 2D –fields that the more widely used tokamaks create.

    PPPL NSTXII
    PPPL NSTX

    The twisty configuration enables stellarators to control the plasma with no need for the current that tokamaks must induce in the gas to complete the magnetic field. Stellarator plasmas thus run little risk of disrupting, as can happen in tokamaks, causing the internal current to abruptly halt and fusion reactions to shut down.

    PPPL has played key roles in the W7-X project. The Laboratory designed and delivered five barn door-sized trim coils that fine-tune the stellarator’s magnetic fields and made their measurement possible. “We’ve confirmed that the magnetic cage that we’ve built works as designed,” said Lazerson, who led roughly half the experiments that validated the configuration of the field. “This reflects U.S. contributions to W7-X,” he added, “and highlights PPPL’s ability to conduct international collaborations.” Support for this work comes from Euratom and the DOE Office of Science.

    To measure the magnetic field, the scientists launched an electron beam along the field lines. They next obtained a cross-section of the entire magnetic surface by using a fluorescent rod to intersect and sweep through the lines, thereby inducing fluorescent light in the shape of the surface.

    Remarkable fidelity

    Results showed a remarkable fidelity to the design of the highly complex magnetic field. “To our knowledge,” the authors write of the discrepancy of less than one part in 100,000, “this is an unprecedented accuracy, both in terms of the as-built engineering of a fusion device, as well as in the measurement of magnetic topology.”

    The W7-X is the most recent version of the stellarator concept, which Lyman Spitzer, a Princeton University astrophysicist and founder of PPPL, originated during the 1950s. Stellarators mostly gave way to tokamaks a decade later, since the doughnut-shaped facilities are simpler to design and build and generally confine plasma better. But recent advances in plasma theory and computational power have led to renewed interest in stellarators.

    Such advances caused the authors to wonder if devices like the W7-X can provide an answer to the question of whether stellarators are the right concept for fusion energy. Years of plasma physics research will be needed to find out, they conclude, and “that task has just started.”

    See the full article here .

    Please help promote STEM in your local schools.

    STEM Icon

    Stem Education Coalition

    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 10:42 am on November 30, 2016 Permalink | Reply
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    From The Conversation: “Fusion energy: A time of transition and potential” 

    Conversation
    The Conversation

    November 29, 2016
    Stewart Prager
    Professor of Astrophysical Science, former director of the Princeton Plasma Physics Laboratory, Princeton University

    Michael C. Zarnstorff
    Deputy Director for Research, Princeton Plasma Physics Laboratory, Princeton University

    1
    fusion energy. murrayashmole

    For centuries, humans have dreamed of harnessing the power of the sun to energize our lives here on Earth. But we want to go beyond collecting solar energy, and one day generate our own from a mini-sun. If we’re able to solve an extremely complex set of scientific and engineering problems, fusion energy promises a green, safe, unlimited source of energy. From just one kilogram of deuterium extracted from water per day could come enough electricity to power hundreds of thousands of homes.

    Since the 1950s, scientific and engineering research has generated enormous progress toward forcing hydrogen atoms to fuse together in a self-sustaining reaction – as well as a small but demonstrable amount of fusion energy. Skeptics and proponents alike note the two most important remaining challenges: maintaining the reactions over long periods of time and devising a material structure to harness the fusion power for electricity.

    As fusion researchers at the Princeton Plasma Physics Lab, we know that realistically, the first commercial fusion power plant is still at least 25 years away.

    PPPLII

    But the potential for its outsize benefits to arrive in the second half of this century means we must keep working. Major demonstrations of fusion’s feasibility can be accomplished earlier – and must, so that fusion power can be incorporated into planning for our energy future.

    Unlike other forms of electrical generation, such as solar, natural gas and nuclear fission, fusion cannot be developed in miniature and then be simply scaled up. The experimental steps are large and take time to build. But the problem of abundant, clean energy will be a major calling for humankind for the next century and beyond. It would be foolhardy not to exploit fully this most promising of energy sources.

    Why fusion power?

    2
    Adding heat to two isotopes of water can result in fusion. American Security Project, CC BY-ND

    In fusion, two nuclei of the hydrogen atom (deuterium and tritium isotopes) fuse together. This is relatively difficult to do: Both nuclei are positively charged, and therefore repel each other. Only if they are moving extremely fast when they collide will they smash together, fuse and thereby release the energy we’re after.

    This happens naturally in the sun. Here on Earth, we use powerful magnets to contain an extremely hot gas of electrically charged deuterium and tritium nuclei and electrons. This hot, charged gas is called a plasma.

    The plasma is so hot – more than 100 million degrees Celsius – that the positively charged nuclei move fast enough to overcome their electrical repulsion and fuse. When the nuclei fuse, they form two energetic particles – an alpha particle (the nucleus of the helium atom) and a neutron.

    Heating the plasma to such a high temperature takes a large amount of energy – which must be put into the reactor before fusion can begin. But once it gets going, fusion has the potential to generate enough energy to maintain its own heat, allowing us to draw off excess heat to turn into usable electricity.

    Fuel for fusion power is abundant in nature. Deuterium is plentiful in water, and the reactor itself can make tritium from lithium. And it is available to all nations, mostly independent of local natural resources.

    Fusion power is clean. It emits no greenhouse gases, and produces only helium and a neutron.

    It is safe. There is no possibility for a runaway reaction, like a nuclear-fission “meltdown.” Rather, if there is any malfunction, the plasma cools, and the fusion reactions cease.

    All these attributes have motivated research for decades, and have become even more attractive over time. But the positives are matched by the significant scientific challenge of fusion.

    Progress to date

    The progress in fusion can be measured in two ways. The first is the tremendous advance in basic understanding of high-temperature plasmas. Scientists had to develop a new field of physics – plasma physics – to conceive of methods to confine the plasma in strong magnetic fields, and then evolve the abilities to heat, stabilize, control turbulence in and measure the properties of the superhot plasma.

    Related technology has also progressed enormously. We have pushed the frontiers in magnets, and electromagnetic wave sources and particle beams to contain and heat the plasma. We have also developed techniques so that materials can withstand the intense heat of the plasma in current experiments.

    It is easy to convey the practical metrics that track fusion’s march to commercialization. Chief among them is the fusion power that has been generated in the laboratory: Fusion power generation escalated from milliwatts for microseconds in the 1970s to 10 megawatts of fusion power (at the Princeton Plasma Physics Laboratory) and 16 megawatts for one second (at the Joint European Torus in England) in the 1990s.

    PPPL NSTX
    PPPL NSTX

    A new chapter in research

    4
    Under construction: the ITER research tokamak in France. ITER

    ITER Tokamak
    ITER Tokamak

    Now the international scientific community is working in unity to construct a massive fusion research facility in France. Called ITER (Latin for “the way”), this plant will generate about 500 megawatts of thermal fusion power for about eight minutes at a time. If this power were converted to electricity, it could power about 150,000 homes. As an experiment, it will allow us to test key science and engineering issues in preparation for fusion power plants that will function continuously.

    ITER employs the design known as the “tokamak,” originally a Russian acronym. It involves a doughnut-shaped plasma, confined in a very strong magnetic field, which is partly created by electrical current that flows in the plasma itself.

    Though it is designed as a research project, and not intended to be a net producer of electric energy, ITER will produce 10 times more fusion energy than the 50 megawatts needed to heat the plasma. This is a huge scientific step, creating the first “burning plasma,” in which most of the energy used to heat the plasma comes from the fusion reaction itself.

    ITER is supported by governments representing half the world’s population: China, the European Union, India, Japan, Russia, South Korea and the U.S. It is a strong international statement about the need for, and promise of, fusion energy.

    The road forward

    From here, the remaining path toward fusion power has two components. First, we must continue research on the tokamak. This means advancing physics and engineering so that we can sustain the plasma in a steady state for months at a time. We will need to develop materials that can withstand an amount of heat equal to one-fifth the heat flux on the surface of the sun for long periods. And we must develop materials that will blanket the reactor core to absorb the neutrons and breed tritium.

    The second component on the path to fusion is to develop ideas that enhance fusion’s attractiveness. Four such ideas are:

    5
    The W-7X stellarator configuration. Max-Planck Institute of Plasmaphysics, CC BY

    Wendelstgein 7-X stellarator
    Wendelstgein 7-X stellarator

    1) Using computers, optimize fusion reactor designs within the constraints of physics and engineering. Beyond what humans can calculate, these optimized designs produce twisted doughnut shapes that are highly stable and can operate automatically for months on end. They are called “stellarators” in the fusion business.

    2) Developing new high-temperature superconducting magnets that can be stronger and smaller than today’s best. That will allow us to build smaller, and likely cheaper, fusion reactors.

    3) Using liquid metal, rather than a solid, as the material surrounding the plasma. Liquid metals do not break, offering a possible solution to the immense challenge how a surrounding material might behave when it contacts the plasma.

    4) Building systems that contain doughnut-shaped plasmas with no hole in the center, forming a plasma shaped almost like a sphere. Some of these approaches could also function with a weaker magnetic field. These “compact tori” and “low-field” approaches also offer the possibility of reduced size and cost.

    Government-sponsored research programs around the world are at work on the elements of both components – and will result in findings that benefit all approaches to fusion energy (as well as our understanding of plasmas in the cosmos and industry). In the past 10 to 15 years, privately funded companies have also joined the effort, particularly in search of compact tori and low-field breakthroughs. Progress is coming and it will bring abundant, clean, safe energy with it.

    See the full article here .

    Please help promote STEM in your local schools.

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    The Conversation US launched as a pilot project in October 2014. It is an independent source of news and views from the academic and research community, delivered direct to the public.
    Our team of professional editors work with university and research institute experts to unlock their knowledge for use by the wider public.
    Access to independent, high quality, authenticated, explanatory journalism underpins a functioning democracy. Our aim is to promote better understanding of current affairs and complex issues. And hopefully allow for a better quality of public discourse and conversation.

     
  • richardmitnick 2:31 pm on November 23, 2016 Permalink | Reply
    Tags: , , PPPL, ,   

    From Princeton: “An explanation for the mysterious onset of a universal process (Physics of Plasmas)” 

    Princeton University
    Princeton University


    PPPL

    November 23, 2016
    John Greenwald, Princeton Plasma Physics Laboratory Communications

    1
    Magnetic reconnection happens in solar flares on the surface in the sun, as well as in experimental fusion energy reactors here on Earth. Image credit: NASA.

    Scientists have proposed a groundbreaking solution to a mystery that has puzzled physicists for decades. At issue is how magnetic reconnection, a universal process that sets off solar flares, northern lights and cosmic gamma-ray bursts, occurs so much faster than theory says should be possible. The answer, proposed by researchers at the U.S. Department of Energy’s (DOE) Princeton Plasma Physics Laboratory (PPPL) and Princeton University, could aid forecasts of space storms, explain several high-energy astrophysical phenomena, and improve plasma confinement in doughnut-shaped magnetic devices called tokamaks designed to obtain energy from nuclear fusion.

    Magnetic reconnection takes place when the magnetic field lines embedded in a plasma — the hot, charged gas that makes up 99 percent of the visible universe — converge, break apart and explosively reconnect. This process takes place in thin sheets in which electric current is strongly concentrated.

    According to conventional theory, these sheets can be highly elongated and severely constrain the velocity of the magnetic field lines that join and split apart, making fast reconnection impossible. However, observation shows that rapid reconnection does exist, directly contradicting theoretical predictions.

    Detailed theory for rapid reconnection

    Now, physicists at PPPL and Princeton University have presented a detailed theory for the mechanism that leads to fast reconnection. Their paper, published in the journal Physics of Plasmas in October, focuses on a phenomenon called “plasmoid instability” to explain the onset of the rapid reconnection process. Support for this research comes from the National Science Foundation and the DOE Office of Science.

    Plasmoid instability, which breaks up plasma current sheets into small magnetic islands called plasmoids, has generated considerable interest in recent years as a possible mechanism for fast reconnection. However, correct identification of the properties of the instability has been elusive.

    The Physics of Plasmas paper addresses this crucial issue. It presents “a quantitative theory for the development of the plasmoid instability in plasma current sheets that can evolve in time” said Luca Comisso, lead author of the study. Co-authors are Manasvi Lingam and Yi-Ming Huang of PPPL and Princeton, and Amitava Bhattacharjee, head of the Theory Department at PPPL and Princeton professor of astrophysical sciences.

    Pierre de Fermat’s principle

    The paper describes how the plasmoid instability begins in a slow linear phase that goes through a period of quiescence before accelerating into an explosive phase that triggers a dramatic increase in the speed of magnetic reconnection. To determine the most important features of this instability, the researchers adapted a variant of the 17th century “principle of least time” originated by the mathematician Pierre de Fermat.

    Use of this principle enabled the researchers to derive equations for the duration of the linear phase, and for computing the growth rate and number of plasmoids created. Hence, this least-time approach led to a quantitative formula for the onset time of fast magnetic reconnection and the physics behind it.

    The paper also produced a surprise. The authors found that such relationships do not reflect traditional power laws, in which one quantity varies as a power of another. “It is common in all realms of science to seek the existence of power laws,” the researchers wrote. “In contrast, we find that the scaling relations of the plasmoid instability are not true power laws – a result that has never been derived or predicted before.”

    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. The Laboratory is managed by Princeton 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.

    See the full article here .

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    Princeton University Campus

    About Princeton: Overview

    Princeton University is a vibrant community of scholarship and learning that stands in the nation’s service and in the service of all nations. Chartered in 1746, Princeton is the fourth-oldest college in the United States. Princeton is an independent, coeducational, nondenominational institution that provides undergraduate and graduate instruction in the humanities, social sciences, natural sciences and engineering.

    As a world-renowned research university, Princeton seeks to achieve the highest levels of distinction in the discovery and transmission of knowledge and understanding. At the same time, Princeton is distinctive among research universities in its commitment to undergraduate teaching.

    Today, more than 1,100 faculty members instruct approximately 5,200 undergraduate students and 2,600 graduate students. The University’s generous financial aid program ensures that talented students from all economic backgrounds can afford a Princeton education.

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  • richardmitnick 11:44 am on October 12, 2016 Permalink | Reply
    Tags: Data drive quests to control nuclear fusion, , PPPL,   

    From PPPL via Princeton University: “Data drive quests to control nuclear fusion” 

    Princeton University
    Princeton University

    10.12.16
    John Sullivan

    1
    Egemen Kolemen (left), assis- tant professor of mechanical and aerospace engineering, speaks with Al von Halle, head of engineering and operations for NSTX-U, a major experiment in nuclear fusion being conducted at the Princeton Plasma Physics Laboratory.

    PPPLII

    PPPL NSTX
    PPPL/NSTX

    Running a fusion reactor is like holding part of the sun in a bottle its heart is a raging storm of particles trapped in a magnetic field.

    To translate this storm’s power into a practical energy source, scientists will have to harness and control the reactor by adjusting the twists and flows of its superheated particles.

    “Plasma can destabilize in milliseconds,” said Egemen Kolemen *08, an assistant professor in mechanical and aerospace engineering and the Andlinger Center for Energy and the Environment. “To control the reaction, we need to react in the same timescale.”

    Kolemen is one of several Princeton engineers working with colleagues at the Princeton Plasma Physics Laboratory (PPPL), a U.S. Department of Energy lab administered by Princeton University, to solve critical problems in making fusion energy a practical reality. In particular, Kolemen and Clarence Rowley ’95, a professor of mechanical and aerospace engineering, lead separate projects to control the behavior of a state of matter known as plasma.

    Instant decisions

    A fusion reactor starts by heating light atoms such as hydrogen gas far beyond the temperature of the sun. At such temperatures, electrons fly free of their atoms leaving a swirl of electrically charged particles called plasma. If engineers can arrange this plasma into just the proper configuration, the particles will slam into each other and fuse into new types of matter, releasing massive amounts of energy. Scientists have been able to do this for minutes at a time, but maintaining a stable reaction for a fusion power plant that needs months to years of operation is a different story. The plasma constantly seeks to fling itself apart. Even if operators prevent this, they still have to control the plasma’s constant twists and swirls to maximize the collisions among particles.

    To make things more complex, there is no easy way to take real-time measurements of plasma’s configuration – observations are possible, but they take time to analyze. That is where Kolemen’s work begins.

    “We gather pieces of diagnostic measurements and quantify the uncertainty,” he said. “We try to put all this information in physics models and figure out what the situation is in the reactor.”

    Kolemen is assembling algorithms that will evaluate measurements of the plasma and make rapid calculations that trigger minute shifts in the reactor. The goal is to create an automated system that reacts quickly enough to maintain stability within the plasma.

    “You need to understand all of the diagnostics, analyze them with the physics, predict if there is going to be a disruption, and take action,” he said.

    It might sound impossible, but Kolemen said the framework of the system is in place. He said engineers are now working to build up the system and increase its reliability.

    “Making something so it works once in a while is easy,” he said. “Going from a system that is functional for 90 percent of the time to the more than 99.99 percent reliability needed for a fusion power plant – that requires a bit more thinking.”

    2
    Clarence Rowley (left) and graduate student Imène Goumiri built on data from previous experiments in nuclear fusion to develop a method to reduce turbulence in the chaotic swarm of ultra-hot particles known as plasma, which is necessary for producing fusion power.

    Finding flow

    While Kolemen seeks tools to control plasmas as they change, Rowley is developing mathematical models that reveal why instabilities develop in the first place.

    To an untrained eye, the plasma seems to twist and roll randomly, but Rowley said that underlying patterns often hide in a multitude of details.

    “If you really want to understand what is going on, to get to the heart of the matter, you want to strip away those details,” Rowley said. “Often, it’s something simple.”

    Imène Goumiri, a graduate student in Rowley’s lab, recently worked with colleagues at Princeton and PPPL to develop a system using mathematical modeling and high-speed controls to reduce turbulence in plasmas created in the lab. Built on data from previous experiments, the program reacts quickly to changes in the plasma’s flow and reduces instabilities by rotating sections of the plasma at different speeds.

    Rowley’s team has revealed how small changes that occur at critical locations and are amplified by other factors. The amplification can eventually cause the small change to play a big role in the overall flow.

    “Trying to identify the features of the flow that are very sensitive to change is a big part of this business,” Rowley said. “Even though this is about fluid dynamics or plasma, it can apply to any domain, which is why it is useful to think about it in a mathematical framework. For instance, if you are trying to understand instabilities in a power grid that could lead to blackouts, you want to know if there are places in the grid that are really vulnerable if one generator went off, it could send ripples through the grid. These same techniques could give you a better understanding of that as well.”

    See the full article here .

    Please help promote STEM in your local schools.

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    Princeton University Campus

    About Princeton: Overview

    Princeton University is a vibrant community of scholarship and learning that stands in the nation’s service and in the service of all nations. Chartered in 1746, Princeton is the fourth-oldest college in the United States. Princeton is an independent, coeducational, nondenominational institution that provides undergraduate and graduate instruction in the humanities, social sciences, natural sciences and engineering.

    As a world-renowned research university, Princeton seeks to achieve the highest levels of distinction in the discovery and transmission of knowledge and understanding. At the same time, Princeton is distinctive among research universities in its commitment to undergraduate teaching.

    Today, more than 1,100 faculty members instruct approximately 5,200 undergraduate students and 2,600 graduate students. The University’s generous financial aid program ensures that talented students from all economic backgrounds can afford a Princeton education.

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  • richardmitnick 9:44 am on October 4, 2016 Permalink | Reply
    Tags: , PPPL, Steven Sabbagh, Steven Sabbagh leads study to predict and avoid disruptions on KSTAR plasmas   

    From PPPL: “Steven Sabbagh leads study to predict and avoid disruptions on KSTAR plasmas” 


    PPPL

    October 3, 2016
    John Greenwald

    1
    Physicist Steven Sabbagh. (Photo by Elle Starkman/Office of Communications)

    Steven Sabbagh, a senior research scientist at Columbia University on long-term assignment to the U.S. Department of Energy’s (DOE) Princeton Plasma Physics Laboratory (PPPL), has been named lead principal investigator for a multi-institutional project on the Korea Superconducting Tokamak Advanced Research (KSTAR) facility.

    2
    KSTAR

    The three-year, $3.3 million collaboration will study methods of predicting and avoiding disruptions on KSTAR, a long-pulse tokamak that produces plasmas that can last from 30 seconds to a design value of more than five minutes.

    Preventing disruptions that can halt fusion reactions and damage the interior walls of tokamaks is a top priority of the U.S. magnetic fusion program; future reactors must operate without disruptions for lengthy periods of time. “Long-pulse is where tokamaks are going,” said Sabbagh. “We are very honored to be granted the opportunity to perform this research.” Support for this work comes from the DOE Office of Science.

    Joining Columbia in the project are PPPL and the Massachusetts Institute of Technology (MIT). Steven Scott, a principal research physicist at PPPL, will lead the PPPL efforts. Earl Marmar, a senior research scientist at MIT, will administer the university’s contribution.

    Conditions leading to disruptions

    The overall effort seeks to model the step-by-step development of conditions that lead to disruptions, and to outline ways to control such conditions. The work will build on research that Sabbagh and the Columbia group have conducted on the National Spherical Torus Experiment (NSTX) at PPPL and will continue on the National Spherical Torus Experiment-Upgrade (NSTX-U).

    Research on the South Korean and PPPL tokamaks will complement each other in the present plan. For example, identifying the steps leading to disruption on KSTAR can be applicable to NSTX-U. The NSTX-U is a low aspect ratio tokamak that takes advantage of the magnetic field geometry with its compact design. This compares with the high aspect ratio KSTAR, which alters the field geometry and hence the plasma confinement and stability properties.

    Low aspect ratio tokamaks are more compact and shaped more like cored apples than wider, doughnut-shaped high aspect tokamaks. Models that can predict and avoid disruptions on both machines are to be tested in these extremes of aspect ratio and at long pulse, which will produce understanding that can be best applied to tokamaks in general.

    Work on the project will proceed on several fronts:

    • Columbia, which will receive $1.7 million of the three-year grant, will model the chain of events leading to disruption of long-pulse plasmas, and will develop techniques for characterizing, forecasting and avoiding such events. Sabbagh and Young-Seok Park, a Columbia associate research scientist on assignment to PPPL, will conduct this research in coordination with the Columbia group’s work on NSTX-U. Included in the group will be Jack Berkery and James Bialek, both on long-term PPPL assignment, together with two post-doctoral research scientists and a student.

    • PPPL and the Plasma Science and Fusion Center at MIT will upgrade the capability of critical diagnostic and analysis systems on KSTAR. Additions will include a 10 channel system to improve KSTAR’s Motional Stark Effect diagnostic, a key instrument for determining plasma stability. Plans call for installation of another 15 channels after the installation and testing of the first system . PPPL will receive $930,000 for the work, with MIT receiving $670,000.

    • Also participating in the project will be PPPL physicists Ben LeBlanc and Dan Boyer. LeBlanc will develop methods to improve the KSTAR Thomson scattering diagnostic, which measures electron temperature and density. Boyer will work with Scott and members of the Columbia group to improve a key code for KSTAR that has been developed to analyze NSTX-U and other fusion experiments.

    Exciting new data

    The overall project “will produce exciting, new and greatly needed data in conjunction with our strong international partners at the National Fusion Research Institute in South Korea,” said Sabbagh. “The present research is the natural and required evolution of past work that now directly applies the plasma stability, transport, and control physics knowledge that has been gained to disruption-event characterization and forecasting and control.”

    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. 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.

    See the full article here .

    Please help promote STEM in your local schools.

    STEM Icon

    Stem Education Coalition

    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 4:38 pm on September 29, 2016 Permalink | Reply
    Tags: , Director Stewart Prager steps down after nSTX failure, , Physics Today insert, PPPL   

    From PPPL: “PPPL Director Stewart Prager Steps Down” 


    PPPL

    September 26, 2016
    Larry Bernard

    Prof. Stewart Prager, a world renowned plasma physicist and passionate voice for a future of clean, abundant and benign energy fueled by fusion, has stepped down today from directorship of the national laboratory he has headed for the last eight years.

    [But two sources who declined to be identified said DOE had forced Prager’s resignation; one source called the move an example of the agency’s “buck stops here” contractor management philosophy. A second source corroborates that account: “This was a firing as much as anything else.”]

    Prager denies that he was asked to resign. “I never spoke to the Office of Science,” he says, adding he had only discussed his resignation with officials at Princeton University, which operates PPPL for DOE. Prager, who is also a professor of astrophysics at Princeton, says he had been considering stepping down since January.

    The NSTX-U has been shut down since the end of July, when one of the machine’s 14 magnets, a poloidal field coil, shorted out after 10 weeks of running time, says Mike Zarnstorff, PPPL deputy director for research. Replacing it, and a second identical coil on the opposite side of the tokamak chamber, will take about a year, he says. The machine was nearly due for a scheduled six-month shutdown for maintenance, he notes.

    The NSTX-U, a $94 million upgrade of a reactor built in 1999, is the world’s most powerful spherical tokamak, with a design field strength of 1 T and heating power of 10–12 MW. It is a variant of the mainstream tokamak technology at laboratories such as the UK’s Joint European Torus and the ITER international fusion collaboration in France. Tokamaks use magnetic fields to bottle up plasmas of hydrogen isotopes, which heats the confined particles to tens of millions of degrees and causes them to fuse into helium.

    Zarnstorff says the root cause of the coil failure is still unknown, although he suspects it was a manufacturing problem. A source close to the lab says the copper wire used in the coil may have been too stiff to accommodate a particular bend in the winding.

    The tokamak was operating at half its maximum design field strength when the problem occurred, Zarnstorff says, and full field operation wasn’t planned until next year. The lab has identified four design simplifications to mitigate risks in the replacement coils. A second defect, a damaged copper cooling tube, was discovered when the machine was taken apart. “We know that copper was an unwise choice,” Zarnstorff says. “It should have been made of stainless steel.”

    During the shutdown, the lab will review the entire NSTX-U design to determine how to implement beneficial design changes and mitigate further risks. “We’ll have to wait and see and do the [analysis] work,” Zarnstorff says.
    David Kramer, Physics Today]

    “It has been a wonderful experience being lab director of the Princeton Plasma Physics Laboratory. But, at the seven-year mark last January I began to think about moving on to the next phase of my life,” Prager said. “The recent technical setback in the NSTX-U facility unexpectedly and suddenly defines a moment that seems to me appropriate for that transition.

    PPPL NSTXII
    NSTX

    It is best for new, continuing leadership to shepherd the rebuilding of the facility and the engineering changes that will be needed over the next year.”

    Prager, the sixth director in the 65-year history of PPPL, joined the Lab in the fall of 2008 after a long career at the University of Wisconsin. A pioneer in plasma physics, he is internationally known for experiments that contribute to the fundamental knowledge of fusion energy and the design of devices that will produce it.

    A professor in the department of astrophysical sciences at Princeton University, Prager will continue research activity at PPPL in fusion energy and plasma physics, beginning with a year’s sabbatical.

    Prof. Dave McComas, Princeton vice president for PPPL, joined Princeton University President Christopher L. Eisgruber in thanking Prager for his dedication to fusion and plasma science. “We are truly grateful to Stewart for his many outstanding contributions and dedicated leadership over the past eight years,” McComas said.

    McComas praised Prager for his leadership in several key initiatives. Among them: founding the Max Planck-Princeton Center for Plasma Physics; increasing joint faculty appointments between Princeton and the Lab; increasing ties between University departments and the Laboratory; developing a fusion communications strategy; broadening the Laboratory’s engagement in low-temperature plasma physics, plasma nanomaterials, laboratory astrophysics, computational fusion science and high energy density physics; and launching a campus plan to modernize the PPPL infrastructure.

    Prof. A.J. Stewart Smith, the former Princeton Vice President for PPPL, said:

    “For more than seven years it has been my great honor and pleasure to work with Stewart, and give whatever assistance I could. In 2008 Stewart towered above the other candidates when we were searching for Rob Goldston’s successor, so we were simply thrilled when he agreed to head the leadership team we proposed to DOE in the competition for the PPPL contract. Stewart’s intelligent but gentle leadership and tireless efforts on behalf of PPPL and the U.S. fusion community have greatly improved communication and cooperation among U.S. fusion institutions. He has also been and continues to be a constant driving force in building an exciting new U.S. research effort to establish stellarators as a strong alternative to tokamaks for practical fusion reactors. I wish him all the best, and great success as he resumes his distinguished scientific career after so many years of dedication to the laboratory. He will be a most difficult act to follow.”

    Dr. Terry Brog, who recently joined the laboratory as deputy director for operations and chief operating officer (COO) at PPPL, will be interim director of the Lab. Dr. Stacia Zelick, chief information officer and head of information technology, will be interim deputy director of operations and COO as the global search for Prager’s successor begins. Dr. Mike Zarnstorff, deputy director for research, will continue to serve in that role.

    PPPL is a DOE national laboratory operated by Princeton University, and the only national lab dedicated to fusion research and plasma science. NSTX-U is a spherical tokamak, or fusion device, producing plasmas many times hotter than the center of the sun to explore the development of fusion as a safe, clean, and abundant energy source to generate electricity for the world. The compact facility confines high pressure plasma in relatively low and cost-effective magnetic fields, and could serve as a model for the next major step in the U.S. fusion program.

    See the full article here .

    Please help promote STEM in your local schools.

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    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 10:28 am on September 23, 2016 Permalink | Reply
    Tags: , , , , PPPL, PTOLEMY laboratory, Tritium   

    From PPPL: “Intern helped get robotic arm on PPPL’s PTOLEMY experiment up and running” 


    PPPL

    September 22, 2016
    Jeanne Jackson DeVoe

    1
    PPPL intern Mark Thom with a device containing a robotic arm that will be used with PPPL’s PTOLEMY experiment, behind him. (Photo by Elle Starkman/PPPL Office of Communications)

    Deep in a laboratory tucked away in the basement of the U.S. Department of Energy’s (DOE) Princeton Plasma Physics Laboratory (PPPL), intern Mark Thom punched commands into a computer as two other students checked a chamber where a silver robotic arm extended from a small port.

    The arm will allow scientists studying neutrinos that originated at the beginning of the universe to load a tiny amount of nuclear material into the device while still maintaining a vacuum in the PTOLEMY laboratory.

    Thom, along with high school interns Xaymara Rivera and Willma Arias de la Rosa, worked closely with Princeton University physicist Chris Tully and PPPL engineers to get the robotic arm moving again. The crucial device will load tritium, a radioactive isotope of hydrogen, into PTOLEMY, the Princeton Tritium Observatory for Light, Early Universe Massive Neutrino Yield.

    Tritium can capture Big Bang neutrinos and release them with electrons in radioactive decay. The neutrinos can provide a tiny boost of energy to the electrons, which PTOLEMY is designed to precisely measure in the darkest, coldest conditions possible. It is funded by the Mark Simons Foundation and the John Templeton Foundation.

    “For me it was just amazing that I actually got onto that project,” Thom said. “It’s exactly the kind of thing I thought I would like to do, being an engineer working on a high-energy physics project.”

    The robotic arm, together with the portable container and the computer program to operate it, were recycled from another experiment when Thom and fellow interns Rivera and Arias de la Rosa began the project. Thom was responsible for making the arm operational and altering it so it would fit PTOLEMY.

    Handling delicate materials

    Tully said the device can safely handle very delicate radioactive materials from DOE’s Savannah River National Laboratory. Without the device, scientists would have to shut down PTOLEMY completely twice a day to change the tritium sample, he said. Maintaining a vacuum in PTOLEMY is also necessary for the extremely sensitive sensors that measure the energy spectrum of the electrons emitted from the tritium to function properly.

    To make the robotic arm function again, Thom had to analyze why the coding was failing, which meant learning the code for the machine. He had to learn an unfamiliar program and then rewrite it to redirect the arm to handle tritium samples, without having worked on a device of that kind before, Tully said.

    The students encountered a setback when the arm stopped working. At first, they thought the device would need a new motor, which would cost $20,000. It turned out that the culprit was a circuit that would cost just a few dollars to replace. While Tully fixed the computer, Thom took the arm apart and researched how to install magnetic shielding around the motors and sketched a design for that shielding, Tully said. “Mark was quite amazing,” he said. “I was very impressed with him.”

    Thom also designed a cover for one of the ports that would need to be sealed for the robotic arm to work. Rivera and Arias de la Rosa helped him operate and test the robotic arm and wrote procedures for running it. Thom and the other interns also worked with PPPL engineers Charles Gentile and Mike Mardenfeld, along with senior mechanical technician Andy Carpe and lead technician Jim Taylor.

    Gentile, who supervised Thom and other engineering interns, said Thom was one of the best interns he has seen in 25 years of supervising more than 200 interns. “He’s an excellent mechanical engineer,” Gentile said. “He was a hard worker and he came up with innovative solutions to problems.”

    The arm connects to PTOLEMY through two ports equipped with valves. One valve connects to the experiment. The other connects to a loading chamber where scientists can insert a tiny sample of tritium on a graphene base.

    Researchers would create a vacuum in the loading chamber and attach it to the vacuum chamber of PTOLEMY. The robotic arm could then collect the tritium and graphene sample and deposit it into PTOLEMY. Researchers would next retract the arm and close the valve connecting it to PTOLEMY.

    Following parents’ footsteps

    Thom, who is in his final year of master’s degree work at Howard University, is from Trinidad. The son of two engineers, he considered becoming a physician and briefly flirted with the idea of being an actor or music producer before choosing to follow in his parents’ footsteps.

    Thom studied engineering as an undergraduate at Howard. He learned about the internship when Andrea Moten, PPPL acting director of human resources, and engineer Atiba Brereton met him at National Laboratory Day at Howard University in February. The two passed Thom’s resume along to Gentile as a candidate for the engineering apprenticeship program.

    The graduate student recently celebrated his one-year anniversary with his wife, Sydney, who is also an engineer and is currently teaching at a Kipp DC Middle School in Washington, D.C. Thom commuted to Washington every weekend on Friday nights to see her and then headed back to New Jersey on Monday mornings. “It was challenging at first,” he said. “But after a while I got accustomed to it and I actually began to appreciate those drives because it gave me some time to think.”

    Thom said he enjoyed the laid-back atmosphere at PPPL. He was surprised when Gentile told him he was overdressed on his first day. But he most enjoyed talking to researchers about their work. “I met some really cool people – a bunch of physicists whom I was able to have certain conversations with, just talking about abstract theories. That’s the kind of conversation I enjoy,” Thom said. “Being able to interact with people like that in that atmosphere was really enjoyable.”

    The internship gave him a better idea of possible careers as he prepares to graduate, Thom said. “I had a limited view of the engineering world prior to going into this work,” he said. “But now I have a better idea of the kind of environment I’d like to be in, so it gives me idea of what I should do to prepare for that environment.”

    See the full article here .

    Please help promote STEM in your local schools.

    STEM Icon

    Stem Education Coalition

    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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