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Scientists reproduce the dynamics behind astrophysical shocks



  Scientists reproduce the dynamics behind astrophysical shocks
NASA recorded solar flares. Picture credits: NASA

High-energy shock waves driven by solar flares from solar flares and coronal mass ejections erupt throughout the solar system, triggering magnetic space storms that can damage satellites, interfere with cell phone service, and shut down power grids on Earth. High-energy waves also drive the solar wind ̵

1; plasma, which emanates constantly from the sun and disturbs the protective magnetic field of the earth.

Now, experiments conducted by researchers at the Princeton Plasma Physics Laboratory (PPPL) of the US Department of Energy (DOE) at the Princeton Center for Heliophysics have for the first time reproduced the process behind the source of such shocks. The findings close the gap between laboratory and spacecraft observations and help to understand how the universe works.

Sudden Jumps

The experiments reported in Physical Review Letters show how the interaction of plasma – the state of matter, which consists of free electrons and atomic nuclei or ions, can be sudden jumps of the Plasma pressure and the magnetic field strength that can accelerate particles to near the speed of light. Such collisions are "collision-free" because they are caused by the interaction of waves and plasma particles rather than by collisions between the particles themselves.

The investigation revealed a measurement of the total flow of impacts. "Direct measurement is an elegant way to see how the particles move and interact with each other," said physicist Derek Schaeffer of PPPL and Princeton University, who led the research. "Our work shows that we can use a powerful diagnostic to study the particle movements that lead to shocks."

Research at the Omega Laser Facility at the University of Rochester revealed a laser-guided plasma called a plunger plasma, which expanded at a supersonic speed of more than one million miles per hour through an existing plasma environment. The expansion accelerated ions in the surrounding plasma to speeds of about half a million miles per hour, simulating the precursor to collision-free shocks that occur throughout the cosmos the plunger plasma reproduced the supersonic plasmas that arise in space. The piston acted like a snow plow and swept away ions from the ambient plasma embedded in a magnetic field.

  • When more of these ions were grown, they formed a barrier that prevented the bulb from continuing to work. "Once you have accumulated enough snow, the damper decouples from the piston," said Schaeffer.
  • The stopped piston passed the formation of the shock to the highly compressed magnetized plasma, resulting in the sudden collision-free jump
  • Researchers used a diagnosis called Thompson scattering to track these developments. The diagnosis detects laser light scattered by the electrons in the plasma and allows the measurement of the temperature and density of the electrons as well as the velocity of the flowing ions. The results, the authors write, show that laboratory experiments investigate the behavior of plasma particles in the precursor of collision-free astrophysical shocks and "can complement and in some cases overcome the limits of similar measurements of spacecraft missions."

    Ultimate Goal

    While this research reproduced the process that causes shocks, the ultimate goal is to self-measure the shock-accelerated particles. For this step, Schaeffer said, "the same diagnosis can be used once we have developed the ability to produce sufficiently strong shocks, and as a bonus," he adds, "it resembles the measurement of particle motion from spacecraft by spacecraft, the Future results can be compared directly. "


    Scientists create the first laboratory generation of astrophysical shockwaves


    Further information:
    D. B. Schaeffer et al., Direct Observations of Particle Dynamics in Magnetized Collision-Free Collision Forerunners in Laser-Produced Plasmas, Physical Review Letters (2019). DOI: 10.1103 / PhysRevLett.122.245001

    Quote :
    Scientists reproduce the dynamics behind astrophysical shocks (July 30, 2019)
    retrieved on July 30, 2019
    from https://phys.org/news/2019-07-scientists-dynamics-astrophysical.html

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