• A roadmap for deepening understanding of

    From ScienceDaily@1:317/3 to All on Fri Apr 22 22:30:48 2022
    A roadmap for deepening understanding of a puzzling universal process


    Date:
    April 22, 2022
    Source:
    DOE/Princeton Plasma Physics Laboratory
    Summary:
    Scientists have detailed a roadmap for untangling a key aspect of
    magnetic recognition that could deepen insight into the workings
    of the cosmos.



    FULL STORY ==========================================================================
    A puzzling process called magnetic reconnection triggers explosive
    phenomena throughout the universe, creating solar flares and space storms
    that can take down mobile phone service and electrical power grids. Now scientists at the U.S. Department of Energy's (DOE) Princeton Plasma
    Physics Laboratory (PPPL) have detailed a roadmap for untangling a key
    aspect of this puzzle that could deepen insight into the workings of
    the cosmos.


    ========================================================================== Reconnection converts the magnetic field energy to particle eruptions
    in astrophysical plasmas by snapping apart and explosively reconnecting
    the magnetic field lines -- a process that occurs within what are called dissipation regions that are often enormously smaller than the regions
    they impact.

    Stressed magnetic field "Plasma doesn't like reconnection," said
    Hantao Ji, a PPPL physicist and Princeton University professor who
    is first author of a paper that details the roadmap in Nature Reviews
    Physics. "However, reconnection does happen when the magnetic field is sufficiently stressed," he said.

    "Dissipation scales are tiny whereas astrophysical scales are very
    large and can extend for millions of miles. Finding a way to bridge these scales through a multiscale mechanism is a key to solving the reconnection puzzle." The roadmap outlines the role of developing technologies with multiscale capabilities such as the Facility for Laboratory Reconnection Experiment (FLARE), a recently installed collaborative facility that is
    being upgraded and will probe facets of magnetic reconnection never before accessible to laboratory experiments. Complementing these experiments
    will be simulations on coming exascale supercomputers that will be 10
    times faster than current computers. "The hope is for FLARE and exascale computing to go hand-in-hand," Ji said.



    ==========================================================================
    The working theory the PPPL roadmap proposes is that multiple plasmoids,
    or magnetic islands, that arise from reconnection along lengthy plasma
    current sheets could bridge the vast range of scales. Such plasmoids
    would correspond more closely to the affected reconnection region, with multiscale laboratory experiments planned to provide the first tests of
    this theory and to evaluate competing hypotheses.

    "Exascale will allow us to do more credible simulations based on
    high-fidelity FLARE experiments," said PPPL physicist Jongsoo Yoo,
    a coauthor of the paper.

    The increased size and power of the new machine -- its diameter will
    be twice that of the sports-utility-vehicle-sized Magnetic Reconnection Experiment (MRX), PPPL's long-standing laboratory experiment -- and will
    enable scientists to replicate reconnection in nature more faithfully.

    "FLARE can access wider astrophysical regimes than MRX with multiple reconnection points and measure the field geometry during reconnection,"
    said William Daughton, a computational scientist at Los Alamos National Laboratory and a coauthor of the paper. "Understanding this physics is important for predicting how reconnection proceeds in solar flares,"
    he said.

    Key challenge A key challenge to the coming experiments will be
    innovating new high- resolution diagnostic systems free from restrictive assumptions. Once developed these systems will enable FLARE to build
    upon satellite sightings such as those produced by the Magnetospheric Multiscale mission, a fleet of four spacecraft launched in 2015 to study reconnection in the magnetosphere, the magnetic field that surrounds
    the Earth.



    ========================================================================== "Progress in understanding multiscale physics critically depends on
    innovation and efficient implementation of such diagnostics systems
    in the coming decade," the paper said. The new findings will address
    open questions that include: o How exactly does reconnection start?
    o How are explosive plasma particles heated and accelerated? o What
    role does reconnection play in related processes such as turbulence and
    space shocks? Overall, "The paper lays out plans to provide the entire
    space physics and astrophysics communities with methods to solve the
    multiscale problem," Yoo said. Such a solution would mark a major step
    toward a more complete understanding of magnetic reconnection in large
    systems throughout the universe.

    Support for this work comes from the DOE Office of Science. Coauthors
    include Jonathan Jara-Almonte of PPPL and Ari Le and Adam Stanier of
    Los Alamos National Laboratory.


    ========================================================================== Story Source: Materials provided by
    DOE/Princeton_Plasma_Physics_Laboratory. Original written by John
    Greenwald. Note: Content may be edited for style and length.


    ========================================================================== Journal Reference:
    1. Hantao Ji, William Daughton, Jonathan Jara-Almonte, Ari Le,
    Adam Stanier,
    Jongsoo Yoo. Magnetic reconnection in the era of exascale computing
    and multiscale experiments. Nature Reviews Physics, 2022; 4 (4):
    263 DOI: 10.1038/s42254-021-00419-x ==========================================================================

    Link to news story: https://www.sciencedaily.com/releases/2022/04/220422131857.htm

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