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  • richardmitnick 4:05 pm on January 31, 2019 Permalink | Reply
    Tags: , , LLNL NIF, Rochester’s laser lab moves closer to controlled nuclear fusion, , With data science   

    From University of Rochester: “With data science, Rochester’s laser lab moves closer to controlled nuclear fusion” 

    U Rochester bloc

    From University of Rochester

    U Rochester Omega Laser

    Scientists have been working for decades to develop controlled nuclear fusion. Controlled nuclear fusion would improve the ability to evaluate the safety and reliability of the nation’s stockpile of nuclear weapons—in labs in lieu of actual test detonations. And ultimately, it could produce an inexhaustible supply of clean energy.

    But the challenges have been many. Notably, designing optimal fusion experiments requires accurately modeling all of the complex physical processes that occur during an implosion. One of the biggest handicaps has been the lack of accurate predictive models to show in advance how target specifications and laser pulse shapes might be altered to increase fusion energy yields.

    Now researchers at the University of Rochester’s Laboratory for Laser Energetics (LLE), along with colleagues from MIT, have been able to triple fusion yields by bringing data science techniques to previously collected data and computer simulations.

    Approaching a fusion milestone

    Rochester’s Laboratory for Laser Energetics is the largest university-based US Department of Energy program in the nation and is home to the OMEGA laser, the most powerful laser system found at any academic institution.

    U Rochester OMEGA EP Laser System

    The facility has taken the lead in the laser direct-drive approach to fusion energy by blasting spherical deuterium-tritium fuel pellets with 60 laser beams, converging directly on the pellet surface from all directions at once. This causes the pellet to heat and implode, forming a plasma. If sufficiently high temperatures and pressures could be confined at the center of the implosion, a thermonuclear burn wave would propagate radially through the entire fuel mass, producing fusion energy yields many times greater than the energy input.

    The latest increase in yields, reported in Nature, bring scientists closer to an important milestone in their quest to achieve controlled thermonuclear fusion – getting the plasma to self-ignite, enabling an output of fusion energy that equals the laser energy coming in.

    “That would be a major achievement but it will require energies much larger than the OMEGA laser such as at the NIF at Lawrence Livermore National Laboratory,” says Michael Campbell, LLE’s director.


    National Ignition Facility at LLNL

    Bridging the gap between experiments and simulations

    To create a predictive model, Varchas Gopalaswamy and Dhrumir Patel, PhD students in mechanical engineering, and their supervisor Riccardo Betti, chief scientist and Robert L . McCrory Professor at LLE, applied data science techniques to results from about 100 previous fusion experiments at OMEGA.

    “We were inspired from advances in machine learning and data science over the last decade,” Gopalaswamy says. Adds Betti: “This approach bridges the gap between experiments and simulations to improve the predictive capability of the computer programs used in the design of experiments.”

    The statistical analysis guided LLE scientists in altering the target specifications and temporal shape of the laser pulse used in the fusion experiments. The task required a concerted effort by LLE experimental physicists who set up the experiments, and theorists who develop the simulation codes. James Knauer, LLE senior scientist, led the experimental campaign.

    “These experiments required exquisite control of the laser pulse shape,” Knauer says. Patel applied the statistical technique to design the laser pulse shape leading to the best performing implosion.

    “This was a very, very unusual pulse shape for us,” Campbell says. And yet, within three or four subsequent experiments, according to Campbell, an experiment was designed that produced 160 trillion fusion reactions, tripling the previous record at OMEGA.

    “Only thanks to the dedication and expertise of the facility crew, target fabrication, cryogenic layering and system scientists, were we able to control the target quality and the laser pulse to the precision required for these experiments,” Betti says.

    Extrapolating to the National Ignition Facility

    When extrapolated to match the 70-times more powerful laser-energies used at the National Ignition Facility (NIF) at Lawrence Livermore National Laboratory, these implosions would be expected to produce about 1,000 times more fusion reactions. Under the right conditions, a modest improvement in target compression on OMEGA could be enough to approach breakeven conditions at NIF energy levels, with the fusion energy output equaling the laser energy input. “Extrapolating the results from OMEGA to NIF is a tricky business. It is not just a size and energy issue. There are also qualitative differences that need to be assessed” Betti said. For this purpose, a parallel effort by LLE scientists in collaboration with colleagues at Lawrence Livermore and the Naval Research Laboratory (NRL) is underway at the NIF to verify that OMEGA results can be extrapolated to NIF energies.

    The NIF is configured for an indirect drive approach to fusion experiments, in which the fuel capsule is enclosed within a metal cylindrical can called a hohlraum. Laser beams enter from the can ends and heat the hohlraum, which in turns produces x-rays that cause the fuel to implode. Unlike OMEGA, NIF beams are not positioned symmetrically, but are instead concentrated along the axis of the hohlraum. The indirect drive scheme has also made major progress in recent experiments at the NIF. “They are getting close to achieve burning-plasma conditions,” Campbell says.

    “The next couple of years we will do experiments on OMEGA using the same asymmetric laser configuration of the NIF, and see what the penalty is.”

    The paper lists a total of 50 LLE scientists and students as coauthors, along with four collaborators from MIT. The target components were made by General Atomics to meet very strict tolerances.

    See the full article here .

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    Please help promote STEM in your local schools.

    Stem Education Coalition

    U Rochester Campus

    The University of Rochesteris one of the country’s top-tier research universities. Our 158 buildings house more than 200 academic majors, more than 2,000 faculty and instructional staff, and some 10,500 students—approximately half of whom are women.

    Learning at the University of Rochester is also on a very personal scale. Rochester remains one of the smallest and most collegiate among top research universities, with smaller classes, a low 10:1 student to teacher ratio, and increased interactions with faculty.

     
  • richardmitnick 3:05 pm on July 11, 2018 Permalink | Reply
    Tags: , LLNL NIF, NIF sets new laser energy record   

    From National Ignition Facility at Lawrence Livermore National Laboratory: “NIF sets new laser energy record” 

    From National Ignition Facility at Lawrence Livermore National Laboratory

    LLNL/NIF

    July 10, 2018

    Breanna Bishop
    bishop33@llnl.gov
    925-423-9802

    LLNL NIF target chamber


    NIF’s target chamber is where the magic happens — temperatures of 100 million degrees and pressures extreme enough to compress the target to densities up to 100 times that of lead are created there. Photo by Jason Laurea/LLNL

    Lawrence Livermore National Laboratory’s (LLNL) National Ignition Facility (NIF) laser system has set a new record, firing 2.15 megajoules (MJ) of energy to its target chamber — a 15 percent improvement over NIF’s design specification of 1.8 MJ, and more than 10 percent higher than the previous 1.9 MJ energy record set in March 2012.

    This demonstration shot successfully meets a National Nuclear Security Administration (NNSA) Level 2 milestone for 2018. NIF, the world’s largest and most energetic laser, is funded by NNSA to serve as a critical research facility supporting the U.S science-based Stockpile Stewardship Program (SSP).

    “NIF’s users are always asking to use more energy in their experiments, because higher energies enhance the science NIF can deliver in support of the stewardship program. These results mark a major step toward increasing NIF’s energy and power capability,” said NIF Director Mark Herrmann. “This demonstration serves as the first step on a path that could allow NIF to operate at substantially higher energies than ever envisioned during NIF’s design.”

    The purpose of this experiment was to demonstrate the highest energy NIF can safely deliver with its current optics and laser configuration. Increasing NIF’s energy limit will expand the parameter space for stewardship experiments and provide a significant boost to the pursuit of ignition — a key element of NNSA’s Stockpile Stewardship Program.

    This work builds on a successful demo laser campaign performed on NIF last year, which utilized just four of NIF’s beams to study the performance limits of the NIF laser. Recently published in Nuclear Fusion, the experimental campaign was designed to assess laser performance limits and operational costs against predictive models. The campaign culminated in the delivery of the highest energies to date and informed the effort to demonstrate 2.1 MJ on the entire 192-beam laser system.

    “The successful 2.1 MJ demonstration is the result of a sustained science and technology investment in NIF and fundamental understanding of optical damage, much of which has been supported by Laboratory Directed Research & Development (LDRD) and other institutional programs,” said NIF & Photon Science Principal Associate Director Jeff Wisoff.

    The NIF laser uses tens of thousands of large precision optical components, including lenses, laser glass slabs, mirrors and frequency conversion crystals to amplify and guide 192 laser beams to a small target in the 10-meter target chamber. Continuous research and development efforts have put these optics at the cutting edge of material science and technology and play a crucial role in raising the laser’s energy and power thresholds. Recent breakthroughs have reduced the level of damage initiation and growth in the optics and led to a reduced cost to mitigate existing damage spots.

    Based on this successful demonstration, NIF is working with LLNL’s ignition program to execute the first ignition experiments that utilize this enhanced energy capability later this summer. Looking ahead, this is the first major step toward extending NIF’s energy and power output through technology development and laser research to extend the NIF mission space and its contributions to the SSP.

    See the full article here .


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    Please help promote STEM in your local schools.

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    The National Ignition Facility, or NIF, is a large laser-based inertial confinement fusion (ICF) research device, located at the Lawrence Livermore National Laboratory in Livermore, California. NIF uses lasers to heat and compress a small amount of hydrogen fuel with the goal of inducing nuclear fusion reactions. NIF’s mission is to achieve fusion ignition with high energy gain, and to support nuclear weapon maintenance and design by studying the behavior of matter under the conditions found within nuclear weapons. NIF is the largest and most energetic ICF device built to date, and the largest laser in the world.

    Construction on the NIF began in 1997 but management problems and technical delays slowed progress into the early 2000s. Progress after 2000 was smoother, but compared to initial estimates, NIF was completed five years behind schedule and was almost four times more expensive than originally budgeted. Construction was certified complete on 31 March 2009 by the U.S. Department of Energy, and a dedication ceremony took place on 29 May 2009. The first large-scale laser target experiments were performed in June 2009 and the first “integrated ignition experiments” (which tested the laser’s power) were declared completed in October 2010.

    Bringing the system to its full potential was a lengthy process that was carried out from 2009 to 2012. During this period a number of experiments were worked into the process under the National Ignition Campaign, with the goal of reaching ignition just after the laser reached full power, some time in the second half of 2012. The Campaign officially ended in September 2012, at about 1⁄10 the conditions needed for ignition. Experiments since then have pushed this closer to 1⁄3, but considerable theoretical and practical work is required if the system is ever to reach ignition. Since 2012, NIF has been used primarily for materials science and weapons research.

    National Igniton Facility- NIF at LLNL

    The preamplifiers of the National Ignition Facility are the first step in increasing the energy of laser beams as they make their way toward the target chamber

    Lawrence Livermore National Laboratory (LLNL) is an American federal research facility in Livermore, California, United States, founded by the University of California, Berkeley in 1952. A Federally Funded Research and Development Center (FFRDC), it is primarily funded by the U.S. Department of Energy (DOE) and managed and operated by Lawrence Livermore National Security, LLC (LLNS), a partnership of the University of California, Bechtel, BWX Technologies, AECOM, and Battelle Memorial Institute in affiliation with the Texas A&M University System. In 2012, the laboratory had the synthetic chemical element livermorium named after it.

    LLNL is self-described as “a premier research and development institution for science and technology applied to national security.” Its principal responsibility is ensuring the safety, security and reliability of the nation’s nuclear weapons through the application of advanced science, engineering and technology. The Laboratory also applies its special expertise and multidisciplinary capabilities to preventing the proliferation and use of weapons of mass destruction, bolstering homeland security and solving other nationally important problems, including energy and environmental security, basic science and economic competitiveness.

    Operated by Lawrence Livermore National Security, LLC, for the Department of Energy’s National Nuclear Security Administration

    DOE Seal
    NNSA

     
  • richardmitnick 3:22 pm on June 14, 2018 Permalink | Reply
    Tags: , , LLNL NIF, NIF achieves record double fusion yield,   

    From NIF at LLNL: “NIF achieves record double fusion yield” 

    From National Ignition Facility at Lawrence Livermore National Laboratory

    LLNL/NIF

    June 13, 2018
    Breanna Bishop
    bishop33@llnl.gov
    925-423-9802

    1
    This rendering of the inside of NIF’s target chamber shows the target positioner moving into place. Pulses from NIF’s high-powered lasers race through the facility at the speed of light and arrive at the center of the target chamber within a few trillionths of a second of each other, aligned to the accuracy of the diameter of a human hair. No image credit.

    An experimental campaign conducted at Lawrence Livermore National Laboratory’s (LLNL) National Ignition Facility (NIF) has achieved a total fusion neutron yield of 1.9e16 (1.9×1016) and 54 KJ of fusion energy output — double the previous record. Researchers in LLNL’s Inertial Confinement Fusion Program (ICF) detail the results in a paper that will be published this week in Physical Review Letters.

    NIF is the world’s largest and most energetic laser, designed to perform experimental studies of fusion ignition and thermonuclear burn, the phenomenon that powers the sun, stars and modern nuclear weapons. As a key component of the National Nuclear Security Administration’s Stockpile Stewardship Program, experiments fielded on NIF enable researchers to gain fundamental understanding of extreme temperatures, pressures and densities — knowledge that helps ensure the current and future nuclear stockpile is safe and reliable.

    The record-breaking experiments utilized a diamond capsule — a layer of ultra-thin high-density carbon containing the deuterium-tritium (DT) fusion fuel — seated inside a depleted uranium hohlraum. This approach allowed the researchers to greatly improve their control over the symmetry of the X-rays that drive the capsule, producing “rounder” and more symmetric implosions.

    “These results represent significant progress,” said Sebastien Le Pape, lead author of the paper and lead experimenter for the campaign. “By controlling the uniformity of the implosion, we’ve improved the compression of the hot spot leading to unprecedented hot spot pressure and areal density.”

    In addition to increased yield, the experiments produced other critical results. For the first time, the hot spot pressure topped out at approximately 360 Gbar (360 billion atmospheres) — exceeding the pressure at the center of the sun. Further, these record yields mean there was a record addition of energy to the hot spot due to fusion alpha particles. By depositing their energy rather than escaping, the alpha particles further heat the fuel, increasing the rate of fusion reactions and thus producing more alpha particles. This leads to yield amplification, which in these experiments was almost a factor of 3. As the implosions are further improved, this yield amplification could eventually lead to fusion ignition.

    “Because of the extreme levels of compression that these implosions have achieved, we are now at the threshold of achieving a ‘burning plasma’ state, where alpha-particle deposition in the fusing plasma is the dominant source of heating in that plasma,” said Omar Hurricane, chief scientist for the ICF Program.

    “Each experiment we do unlocks important data that informs how we design and field future experiments,” added NIF Director Mark Herrmann. “These results represent a significant advancement in our knowledge and will enable our next steps in tackling the difficult scientific challenge of ignition.”

    In addition, the experiments achieved conditions that now enable access to a range of nuclear and astrophysical regimes. The density, temperature and pressure of the hot spot are the closest to conditions in the sun, and the neutron density is now applicable for nucleosynthesis studies, which have traditionally needed an intense, laboratory-based neutron source. The conditions also are relevant for studying fundamental nuclear weapons physics.

    Additional experiments have shown similar levels of performance, confirming the importance of this approach. Looking ahead, LLNL plans to advance its experiments by exploring increased capsule size, energy delivery on NIF and improvements to features such as the capsule fill tube.

    “Every time we make progress, we can better understand what challenges lie ahead,” said Laura Berzak Hopkins, lead designer for the experiments. “Now, we’re in an exciting place where we understand our system a lot better than before, and we’ve been able to take that understanding and translate it into increased performance. I’m very excited about the progress we’ve been able to make, and where we can go next.”

    In addition to Le Pape, Hurricane and Berzak Hopkins, co-authors include Laurent Divol, Arthur Pak, Eduard Dewald, Suhas Bhandarkar, Laura Benedetti, Thomas Bunn, Juergen Biener, Daniel Casey, David Fittinghoff, Clement Goyon, Steven Haan, Robert Hatarik, Darwin Ho, Nobuhiko Izumi, Shahab Khan, Tammy Ma, Andrew Mackinnon, Andrew MacPhee, Brian MacGowan, Nathan Meezan, Jose Milovich, Marius Millot, Pierre Michel, Sabrina Nagel, Abbas Nikroo, Prav Patel, Joseph Ralph, Janes Ross, David Strozzi, Michael Stadermann, Charles Yeamans, Christopher Weber and Deborah Callahan of LLNL; Jay Crippen Martin Havre, Javier Jaquez and Neal Rice of General Atomics; Dana Edgell of the University of Rochester’s Laboratory for Laser Energetics; Maria Gatu-Johnson of the Massachusetts Institute of Technology’s Plasma Science and Fusion Center; George Kyrala and Petr Volegov of Los Alamos National Laboratory; and Christoph Wild of Diamond Materials Gmbh.

    See the full article here .


    five-ways-keep-your-child-safe-school-shootings

    Please help promote STEM in your local schools.

    Stem Education Coalition

    The National Ignition Facility, or NIF, is a large laser-based inertial confinement fusion (ICF) research device, located at the Lawrence Livermore National Laboratory in Livermore, California. NIF uses lasers to heat and compress a small amount of hydrogen fuel with the goal of inducing nuclear fusion reactions. NIF’s mission is to achieve fusion ignition with high energy gain, and to support nuclear weapon maintenance and design by studying the behavior of matter under the conditions found within nuclear weapons. NIF is the largest and most energetic ICF device built to date, and the largest laser in the world.

    Construction on the NIF began in 1997 but management problems and technical delays slowed progress into the early 2000s. Progress after 2000 was smoother, but compared to initial estimates, NIF was completed five years behind schedule and was almost four times more expensive than originally budgeted. Construction was certified complete on 31 March 2009 by the U.S. Department of Energy, and a dedication ceremony took place on 29 May 2009. The first large-scale laser target experiments were performed in June 2009 and the first “integrated ignition experiments” (which tested the laser’s power) were declared completed in October 2010.

    Bringing the system to its full potential was a lengthy process that was carried out from 2009 to 2012. During this period a number of experiments were worked into the process under the National Ignition Campaign, with the goal of reaching ignition just after the laser reached full power, some time in the second half of 2012. The Campaign officially ended in September 2012, at about 1⁄10 the conditions needed for ignition. Experiments since then have pushed this closer to 1⁄3, but considerable theoretical and practical work is required if the system is ever to reach ignition. Since 2012, NIF has been used primarily for materials science and weapons research.

    National Igniton Facility- NIF at LLNL

    The preamplifiers of the National Ignition Facility are the first step in increasing the energy of laser beams as they make their way toward the target chamber

    Lawrence Livermore National Laboratory (LLNL) is an American federal research facility in Livermore, California, United States, founded by the University of California, Berkeley in 1952. A Federally Funded Research and Development Center (FFRDC), it is primarily funded by the U.S. Department of Energy (DOE) and managed and operated by Lawrence Livermore National Security, LLC (LLNS), a partnership of the University of California, Bechtel, BWX Technologies, AECOM, and Battelle Memorial Institute in affiliation with the Texas A&M University System. In 2012, the laboratory had the synthetic chemical element livermorium named after it.

    LLNL is self-described as “a premier research and development institution for science and technology applied to national security.”[1] Its principal responsibility is ensuring the safety, security and reliability of the nation’s nuclear weapons through the application of advanced science, engineering and technology. The Laboratory also applies its special expertise and multidisciplinary capabilities to preventing the proliferation and use of weapons of mass destruction, bolstering homeland security and solving other nationally important problems, including energy and environmental security, basic science and economic competitiveness.

    Operated by Lawrence Livermore National Security, LLC, for the Department of Energy’s National Nuclear Security Administration

    DOE Seal
    NNSA

     
  • richardmitnick 7:06 am on February 7, 2018 Permalink | Reply
    Tags: , First experimental evidence for superionic ice, , LLNL NIF, , U Rochester's Laboratory for Laser Energetics, Uranus and Neptune might contain vast amount of superionic water ice   

    From LLNL: “First experimental evidence for superionic ice” 


    Lawrence Livermore National Laboratory

    Feb. 5, 2018
    Breanna Bishop
    bishop33@llnl.gov
    925-423-9802

    1
    Time-integrated image of a laser-driven shock compression experiment to recreate planetary interior conditions and study the properties of superionic water. Image by M. Millot/E. Kowaluk/J.Wickboldt/LLNL/LLE/NIF

    U Rochester’s Laboratory for Laser Energetics

    LLNL/NIF

    Among the many discoveries on matter at high pressure that garnered him the Nobel Prize in 1946, scientist Percy Bridgman discovered five different crystalline forms of water ice, ushering in more than 100 years of research into how ice behaves under extreme conditions.

    One of the most intriguing properties of water is that it may become superionic when heated to several thousand degrees at high pressure, similar to the conditions inside giant planets like Uranus and Neptune. This exotic state of water is characterized by liquid-like hydrogen ions moving within a solid lattice of oxygen.

    Since this was first predicted in 1988, many research groups in the field have confirmed and refined numerical simulations, while others used static compression techniques to explore the phase diagram of water at high pressure. While indirect signatures were observed, no research group has been able to identify experimental evidence for superionic water ice — until now.

    In a paper published today by Nature Physics , a research team from Lawrence Livermore National Laboratory (LLNL), the University of California, Berkeley and the University of Rochester provides experimental evidence for superionic conduction in water ice at planetary interior conditions, verifying the 30-year-old prediction.

    Using shock compression, the team identified thermodynamic signatures showing that ice melts near 5000 Kelvin (K) at 200 gigapascals (GPa — 2 million times Earth’s atmosphere) — 4000 K higher than the melting point at 0.5 megabar (Mbar) and almost the surface temperature of the sun.

    “Our experiments have verified the two main predictions for superionic ice: very high protonic/ionic conductivity within the solid and high melting point,” said lead author Marius Millot, a physicist at LLNL. “Our work provides experimental evidence for superionic ice and shows that these predictions were not due to artifacts in the simulations, but actually captured the extraordinary behavior of water at those conditions. This provides an important validation of state-of-the-art quantum simulations using density-functional-theory-based molecular dynamics (DFT-MD).”

    “Driven by the increase in computing resources available, I feel we have reached a turning point,” added Sebastien Hamel, LLNL physicist and co-author of the paper. “We are now at a stage where a large enough number of these simulations can be run to map out large parts of the phase diagram of materials under extreme conditions in sufficient detail to effectively support experimental efforts.”

    2
    Visualization of molecular dynamics simulations showing the fast diffusion of hydrogen ions (pink trajectories) within the solid lattice of oxygen in superionic ice. Image by S. Hamel/M. Millot/J.Wickboldt/LLNL/NIF

    Using diamond anvil cells (DAC), the team applied 2.5 GPa of pressure (25 thousand atmospheres) to pre-compress water into the room-temperature ice VII, a cubic crystalline form that is different from “ice-cube” hexagonal ice, in addition to being 60 percent denser than water at ambient pressure and temperature. They then shifted to the University of Rochester’s Laboratory for Laser Energetics (LLE) to perform laser-driven shock compression of the pre-compressed cells. They focused up to six intense beams of LLE’s Omega-60 laser, delivering a 1 nanosecond pulse of UV light onto one of the diamonds. This launched strong shock waves of several hundred GPa into the sample, to compress and heat the water ice at the same time.

    “Because we pre-compressed the water, there is less shock-heating than if we shock-compressed ambient liquid water, allowing us to access much colder states at high pressure than in previous shock compression studies, so that we could reach the predicted stability domain of superionic ice,” Millot said.

    The team used interferometric ultrafast velocimetry and pyrometry to characterize the optical properties of the shocked compressed water and determine its thermodynamic properties during the brief 10-20 nanosecond duration of the experiment, before pressure release waves decompressed the sample and vaporized the diamonds and the water.

    “These are very challenging experiments, so it was really exciting to see that we could learn so much from the data — especially since we spent about two years making the measurements and two more years developing the methods to analyze the data,” Millot said.

    This work also has important implications for planetary science because Uranus and Neptune might contain vast amount of superionic water ice. Planetary scientists believe these giant planets are made primarily of a carbon, hydrogen, oxygen and nitrogen (C-H-O-N) mixture that corresponds to 65 percent water by mass, mixed with ammonia and methane.

    Many scientists envision these planets with fully fluid convecting interiors. Now, the experimental discovery of superionic ice should give more strength to a new picture for these objects with a relatively thin layer of fluid and a large “mantle” of superionic ice. In fact, such a structure was proposed a decade ago — based on dynamo simulation — to explain the unusual magnetic fields of these planets. This is particularly relevant as NASA is considering launching a probe to Uranus and/or Neptune, in the footsteps of the successful Cassini and Juno missions to Saturn and Jupiter.

    “Magnetic fields provide crucial information about the interiors and evolution of planets, so it is gratifying that our experiments can test — and in fact, support — the thin-dynamo idea that had been proposed for explaining the truly strange magnetic fields of Uranus and Neptune,” said Raymond Jeanloz, co-author on the paper and professor in Earth & Planetary Physics and Astronomy at the University of California, Berkeley. It’s also mind-boggling that frozen water ice is present at thousands of degrees inside these planets, but that’s what the experiments show.”

    “The next step will be to determine the structure of the oxygen lattice,” said Federica Coppari, LLNL physicist and co-author of the paper. “X-ray diffraction is now routinely performed in laser-shock experiments at Omega and it will allow to determine experimentally the crystalline structure of superionic water. This would be very exciting because theoretical simulations struggle to predict the actual structure of superionic water ice.”

    Looking ahead, the team plans to push to higher pre-compression and extend the technique to other materials, such as helium, that would be more representative of planets like Saturn and Jupiter.

    Co-authors include Hamel, Peter Celliers, Coppari, Dayne Fratanduono, Damian Swift and Jon Eggert from LLNL; Jeanloz from UC Berkeley; and Ryan Rygg and Gilbert Collins, previously at LLNL and now at the University of Rochester. The experiments also were supported by target fabrication efforts by LLNL’s Stephanie Uhlich, Antonio Correa Barrios, Carol Davis, Jim Emig, Eric Folsom, Renee Posadas Soriano, Walter Unites and Timothy Uphaus.

    See the full article here .

    Please help promote STEM in your local schools.

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    Stem Education Coalition
    LLNL Campus

    Operated by Lawrence Livermore National Security, LLC, for the Department of Energy’s National Nuclear Security
    Administration
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  • richardmitnick 10:31 am on January 5, 2018 Permalink | Reply
    Tags: , , Computational astrophysics team uncloaks magnetic fields of cosmic events, Flash Center for Computational Science, , LLNL NIF, , ,   

    From U Chicago: “Computational astrophysics team uncloaks magnetic fields of cosmic events” 

    U Chicago bloc

    University of Chicago

    January 4, 2018
    Rob Mitchum

    New method enhances study of stars, black holes in laboratory settings.

    1
    Computational astrophysicists describe a new method for acquiring information on experiments using laser beams to reproduce cosmic conditions. Courtesy of
    Lawrence Livermore National Laboratory

    The development of ultra-intense lasers delivering the same power as the entire U.S. power grid has enabled the study of cosmic phenomena such as supernovae and black holes in earthbound laboratories. Now, a new method developed by computational astrophysicists at the University of Chicago allows scientists to analyze a key characteristic of these events: their powerful and complex magnetic fields.

    In the field of high-energy density physics, or HEDP, scientists study a wide range of astrophysical objects—stars, supermassive black holes at the center of galaxies and galaxy clusters—with laboratory experiments as small as a penny and lasting only a few billionths of a second. By focusing powerful lasers on a carefully designed target, researchers can produce plasmas that reproduce conditions observed by astronomers in our sun and distant galaxies.

    Planning these complex and expensive experiments requires large-scale, high-fidelity computer simulation beforehand. Since 2012, the Flash Center for Computational Science of the Department of Astronomy & Astrophysics at UChicago has provided the leading open computer code, called FLASH, for these HEDP simulations, enabling researchers to fine-tune experiments and develop analysis methods before execution at sites such as the National Ignition Facility at Lawrence Livermore National Laboratory or the OMEGA Laser Facility in Rochester, N.Y.


    LLNL/NIF

    2
    OMEGA Laser Facility, U Rochester

    “As soon as FLASH became available, there was kind of a stampede to use it to design experiments,” said Petros Tzeferacos, research assistant professor of astronomy and astrophysics and associate director of the Flash Center.

    During these experiments, laser probe beams can provide researchers with information about the density and temperature of the plasma. But a key measurement, the magnetic field, has remained elusive. To try and tease out magnetic field measurements from extreme plasma conditions, scientists at MIT developed an experimental diagnostic technique that uses charged particles instead, called proton radiography.

    In a new paper for the journal Review of Scientific Instruments, Flash Center scientists Carlo Graziani, Donald Lamb and Tzeferacos, with MIT’s Chikang Li, describe a new method for acquiring quantitative, high-resolution information about these magnetic fields. Their discovery, refined using FLASH simulations and real experimental results, opens new doors for understanding cosmic phenomena.

    “We chose to go after experiments motivated by astrophysics where magnetic fields were important,” said Lamb, the Robert A. Millikan Distinguished Service Professor Emeritus in Astronomy & Astrophysics and director of the Flash Center. “The creation of the code plus the need to try to figure out how to understand what magnetic fields are created caused us to build this software, that can for the first time quantitatively reconstruct the shape and strength of the magnetic field.”

    Skyrocketing experiments

    In proton radiography, energetic protons are shot through the magnetized plasma towards a detector on the other side. As the protons pass through the magnetic field, they are deflected from their path, forming a complex pattern on the detector. These patterns were difficult to interpret, and previous methods could only make general statements about the field’s properties.

    “Magnetic fields play important roles in essentially almost every astrophysical phenomena. If you aren’t able to actually look at what’s happening, or study them, you’re missing a key part of almost every astrophysical object or process that you’re interested in,” said Tzeferacos.

    By conducting simulated experiments with known magnetic fields, the Flash Center team constructed an algorithm that can reconstruct the field from the proton radiograph pattern. Once calibrated computationally, the method was applied to experimental data collected at laser facilities, revealing new insights about astrophysical events.

    The combination of the FLASH code, the development of the proton radiography diagnostic, and the ability to reconstruct magnetic fields from the experimental data, are revolutionizing laboratory plasma astrophysics and HEDP. “The availability of these tools has caused the number of HEDP experiments that study magnetic fields to skyrocket,” said Lamb.

    The new software for magnetic field reconstruction, called PRaLine, will be shared with the community both as part of the next FLASH code release and as a separate component available on GitHub. Lamb and Tzeferacos said they expect it to be used for studying many astrophysics topics, such as the annihilation of magnetic fields in the solar corona; astrophysical jets produced by young stellar objects, the Crab Nebula pulsar, and the supermassive black holes at the center of galaxies; and the amplification of magnetic fields and acceleration of cosmic rays by shocks in supernova remnants.

    “The types of experiments HEDP scientists perform now are very diverse,” said Tzeferacos. “FLASH contributed to this diversity, because it enables you to think outside the box, try different simulations of different configurations, and see what plasma conditions you are able to achieve.”

    The work was funded by grants from the U.S. Department of Energy and the National Science Foundation.

    See the full article here .

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    An intellectual destination

    One of the world’s premier academic and research institutions, the University of Chicago has driven new ways of thinking since our 1890 founding. Today, UChicago is an intellectual destination that draws inspired scholars to our Hyde Park and international campuses, keeping UChicago at the nexus of ideas that challenge and change the world.

     
  • richardmitnick 5:34 pm on November 21, 2017 Permalink | Reply
    Tags: A high-resolution X-ray spectrometer for the largest and most powerful laser facility in the world, LLNL NIF,   

    From PPPL: “PPPL scientists deliver new high-resolution diagnostic to national laser facility” 


    PPPL

    November 21, 2017
    Raphael Rosen

    1
    PPPL physicist Lan Gao performing the final check for crystal positioning and alignment before the instrument was shipped to NIF.

    2
    The three spectrometer channels inside the instrument. (Photo by Elle Starkman)

    4
    A cross section of the instrument showing three crystal spectrometers. (Photo by Elle Starkman)

    Scientists from the U.S. Department of Energy’s (DOE) Princeton Plasma Physics Laboratory (PPPL) have built and delivered a high-resolution X-ray spectrometer for the largest and most powerful laser facility in the world.


    LLNL/NIF

    The diagnostic, installed on the National Ignition Facility (NIF) at the DOE’s Lawrence Livermore National Laboratory, will analyze and record data from high-energy density experiments created by firing NIF’s 192 lasers at tiny pellets of fuel. Such experiments are relevant to projects that include the U.S. Stockpile Stewardship Program, which maintains the U.S. nuclear deterrent without full-scale testing, and to inertial confinement fusion, an alternative to the magnetic confinement fusion that PPPL studies.

    PPPL has used spectrometers for decades to analyze the electromagnetic spectrum of plasma, the hot fourth state of matter in which electrons have separated from atomic nuclei, inside doughnut-shaped fusion devices known as tokamaks. These devices heat the particles and confine them in magnetic fields, causing the nuclei to fuse and produce fusion energy. By contrast, NIF’s high-powered lasers cause fusion by heating the exterior of the fuel pellet. As the exterior vaporizes, pressure extends inward towards the pellet’s core, crushing hydrogen atoms together until they fuse and release their energy.

    NIF tested and confirmed that the spectrometer was operating as expected on September 28. During the experiment, the device accurately measured the electron temperature and density of a fuel capsule during the fusion process. “Measuring these conditions is key to achieving ignition of a self-sustaining fusion process on NIF,” said PPPL physicist Lan Gao, who helped design and build the device. “Everything worked out very nicely. The signal level we got was just like what we predicted.”

    The spectrometer will focus on a small capsule of simulated fuel that includes the element krypton to measure how the density and temperature of the hot electrons in the plasma change over time. “The fusion yield is very sensitive to temperature,” said Marilyn Schneider, leader of NIF’s Radiation Physics and Spectroscopic Diagnostics Group. “The spectrometer will provide the most sensitive temperature measurements to date. The device’s ability to plot temperature against time will also be very helpful.”

    Other PPPL researchers who contributed to this project include Principal Research Physicist Ken Hill; the Head of the Plasma Science & Technology Department Phil Efthimion; and graduate student Brian Kraus.

    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 5:21 am on May 16, 2017 Permalink | Reply
    Tags: , , LLNL NIF, , Particle acceleration, , Rochester’s Laboratory for Laser Energetics,   

    From ALCF: “Fields and flows fire up cosmic accelerators” 

    Argonne Lab
    News from Argonne National Laboratory

    ANL Cray Aurora supercomputer
    Cray Aurora supercomputer at the Argonne Leadership Computing Facility

    MIRA IBM Blue Gene Q supercomputer at the Argonne Leadership Computing Facility
    MIRA IBM Blue Gene Q supercomputer at the Argonne Leadership Computing Facility

    ALCF

    May 15, 2017
    John Spizzirri

    1
    A visualization from a 3D OSIRIS simulation of particle acceleration in laser-driven magnetic reconnection. The trajectories of the most energetic electrons (colored by energy) are shown as the two magnetized plasmas (grey isosurfaces) interact. Electrons are accelerated by the reconnection electric field at the interaction region and escape in a fan-like profile. Credit: Frederico Fiuza, SLAC National Accelerator Laboratory/OSIRIS

    Every day, with little notice, the Earth is bombarded by energetic particles that shower its inhabitants in an invisible dusting of radiation, observed only by the random detector, or astronomer, or physicist duly noting their passing. These particles constitute, perhaps, the galactic residue of some far distant supernova, or the tangible echo of a pulsar. These are cosmic rays.

    But how are these particles produced? And where do they find the energy to travel unchecked by immense distances and interstellar obstacles?

    These are the questions Frederico Fiuza has pursued over the last three years, through ongoing projects at the Argonne Leadership Computing Facility (ALCF), a U.S. Department of Energy (DOE) Office of Science User Facility.

    A physicist at the SLAC National Accelerator Laboratory in California, Fiuza and his team are conducting thorough investigations of plasma physics to discern the fundamental processes that accelerate particles.

    The answers could provide an understanding of how cosmic rays gain their energy and how similar acceleration mechanisms could be probed in the laboratory and used for practical applications.

    While the “how” of particle acceleration remains a mystery, the “where” is slightly better understood. “The radiation emitted by electrons tells us that these particles are accelerated by plasma processes associated with energetic astrophysical objects,” says Fiuza.

    The visible universe is filled with plasma, ionized matter formed when gas is super-heated, separating electrons from ions. More than 99 percent of the observable universe is made of plasmas, and the radiation emitted from them creates the beautiful, eerie colors that accentuate nebulae and other astronomical wonders.

    The motivation for these projects came from asking whether it was possible to reproduce similar plasma conditions in the laboratory and study how particles are accelerated.

    High-power lasers, such as those available at the University of Rochester’s Laboratory for Laser Energetics or at the National Ignition Facility in the Lawrence Livermore National Laboratory, can produce peak powers in excess of 1,000 trillion watts.

    2
    Rochester’s Laboratory for Laser Energetics


    At these high-powers, lasers can instantly ionize matter and create energetic plasma flows for the desired studies of particle acceleration.

    Intimate Physics

    To determine what processes can be probed and how to conduct experiments efficiently, Fiuza’s team recreates the conditions of these laser-driven plasmas using large-scale simulations. Computationally, he says, it becomes very challenging to simultaneously solve for the large scale of the experiment and the very small-scale physics at the level of individual particles, where these flows produce fields that in turn accelerate particles.

    Because the range in scales is so dramatic, they turned to the petascale power of Mira, the ALCF’s Blue Gene/Q supercomputer, to run the first-ever 3D simulations of these laboratory scenarios. To drive the simulation, they used OSIRIS, a state-of-the-art, particle-in-cell code for modeling plasmas, developed by UCLA and the Instituto Superior Técnico, in Portugal, where Fiuza earned his PhD.

    Part of the complexity involved in modeling plasmas is derived from the intimate coupling between particles and electromagnetic radiation — particles emit radiation and the radiation affects the motion of the particles.

    In the first phase of this project, Fiuza’s team showed that a plasma instability, the Weibel instability, is able to convert a large fraction of the energy in plasma flows to magnetic fields. They have shown a strong agreement in a one-to-one comparison of the experimental data with the 3D simulation data, which was published in Nature Physics, in 2015. This helped them understand how the strong fields required for particle acceleration can be generated in astrophysical environments.

    Fiuza uses tennis as an analogy to explain the role these magnetic fields play in accelerating particles within shock waves. The net represents the shockwave and the racquets of the two players are akin to magnetic fields. If the players move towards the net as they bounce the ball between each other, the ball, or particles, rapidly accelerate.

    “The bottom line is, we now understand how magnetic fields are formed that are strong enough to bounce these particles back and forth to be energized. It’s a multi-step process: you need to start by generating strong fields — and we found an instability that can generate strong fields from nothing or from very small fluctuations — and then these fields need to efficiently scatter the particles,” says Fiuza.

    Reconnecting

    NASA Magnetic reconnection, Credit: M. Aschwanden et al. (LMSAL), TRACE, NASA

    But particles can be energized in another way if the system provides the strong magnetic fields from the start.

    “In some scenarios, like pulsars, you have extraordinary magnetic field amplitudes,” notes Fiuza. “There, you want to understand how the enormous amount of energy stored in these fields can be directly transferred to particles. In this case, we don’t tend to think of flows or shocks as the dominant process, but rather magnetic reconnection.”

    Magnetic reconnection, a fundamental process in astrophysical and fusion plasmas, is believed to be the cause of solar flares, coronal mass ejections, and other volatile cosmic events. When magnetic fields of opposite polarity are brought together, their topologies are changed. The magnetic field lines rearrange in such a way as to convert magnetic energy into heat and kinetic energy, causing an explosive reaction that drives the acceleration of particles. This was the focus of Fiuza’s most recent project at the ALCF.

    Again, Fiuza’s team modeled the possibility of studying this process in the laboratory with laser-driven plasmas. To conduct 3D, first-principles simulations (simulations derived from fundamental theoretical assumptions/predictions), Fiuza needed to model tens of billions of particles to represent the laser-driven magnetized plasma system. They modeled the motion of every particle and then selected the thousand most energetic ones. The motion of those particles was individually tracked to determine how they were accelerated by the magnetic reconnection process.

    “What is quite amazing about these cosmic accelerators is that a very, very small number of particles carry a large fraction of the energy in the system, let’s say 20 percent. So you have this enormous energy in this astrophysical system, and from some miraculous process, it all goes to a few lucky particles,” he says. “That means that the individual motion of particles and the trajectory of particles are very important.”

    The team’s results, which were published in Physical Review Letters, in 2016, show that laser-driven reconnection leads to strong particle acceleration. As two expanding plasma plumes interact with each other, they form a thin current sheet, or reconnection layer, which becomes unstable, breaking into smaller sheets. During this process, the magnetic field is annihilated and a strong electric field is excited in the reconnection region, efficiently accelerating electrons as they enter the region.

    Fiuza expects that, like his previous project, these simulation results can be confirmed experimentally and open a window into these mysterious cosmic accelerators.

    This research is supported by the DOE Office of Science. Computing time at the ALCF was allocated through the Innovative and Novel Computational Impact on Theory and Experiment (INCITE) program.

    See the full article here .

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    Argonne National Laboratory seeks solutions to pressing national problems in science and technology. The nation’s first national laboratory, Argonne conducts leading-edge basic and applied scientific research in virtually every scientific discipline. Argonne researchers work closely with researchers from hundreds of companies, universities, and federal, state and municipal agencies to help them solve their specific problems, advance America’s scientific leadership and prepare the nation for a better future. With employees from more than 60 nations, Argonne is managed by UChicago Argonne, LLC for the U.S. Department of Energy’s Office of Science. For more visit http://www.anl.gov.

    About ALCF

    The Argonne Leadership Computing Facility’s (ALCF) mission is to accelerate major scientific discoveries and engineering breakthroughs for humanity by designing and providing world-leading computing facilities in partnership with the computational science community.

    We help researchers solve some of the world’s largest and most complex problems with our unique combination of supercomputing resources and expertise.

    ALCF projects cover many scientific disciplines, ranging from chemistry and biology to physics and materials science. Examples include modeling and simulation efforts to:

    Discover new materials for batteries
    Predict the impacts of global climate change
    Unravel the origins of the universe
    Develop renewable energy technologies

    Argonne is managed by UChicago Argonne, LLC for the U.S. Department of Energy’s Office of Science

    Argonne Lab Campus

     
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