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    The Gusty Winds Of Space Turbulence Measured In A Terrestrial Lab
    By News Staff | December 24th 2012 11:33 PM | 1 comment | Print | E-mail | Track Comments

    There are some kinds of turbulence we know exists but proving it is difficult - turbulence in the ionized gas that fills the universe is one such example.

    But now a research team says they have directly measured it for the first time - in the laboratory.


    One well-known source of gusty space winds are the violent emissions of charged particles from the sun, known as coronal mass ejections. These solar-powered winds can adversely affect satellite communications, air travel and the electric power grid. On the positive side, solar storms also can also lead to mesmerizing auroras at the north and south poles on Earth.

     Unlike gusts of wind on the surface of the Earth, turbulent motions in space and astrophysical systems are governed by Alfven waves, which are traveling disturbances of the plasma and magnetic field. Nonlinear interactions between Alfven waves traveling up and down the magnetic field—such as two magnetic waves colliding to create a third wave—are a fundamental building block of plasma turbulence, and modern theories of astrophysical turbulence are based on this underlying concept. 


    A solar prominence erupts into the sun's corona. : Image courtesy of NASA

    "Turbulence is not restricted to environments here on Earth, but also arises pervasively throughout the solar system and beyond, driving chaotic motions in the ionized gas, or plasma, that fills the universe," says Gregory Howes, assistant professor of physics and astronomy at the University of Iowa and lead author of the paper in Physical Review Letters. "It is thought to play a key role in heating the atmosphere of the sun, the solar corona, to temperatures of a million degrees Celsius, nearly a thousand times hotter than the surface of the sun.

    "Turbulence also regulates the formation of the stars throughout the galaxy, determines the radiation emitted from the super massive black hole at the center of our galaxy and mediates the effects that space weather has on the Earth. We have presented the first experimental measurement in a laboratory plasma of the nonlinear interaction between counter-propagating Alfven waves, the fundamental building block of astrophysical turbulence."


    Comments

    rholley
    These  magnetohydrodynamic (MHD) waves are named after Hannes Olof Gösta Alfvén, the Swedish electrical engineer, plasma physicist who won the 1970 Nobel Prize in Physics for their discovery.

    Perhaps it’s because of the aurorae visible from the northern latitudes, but Scandinavians have made outstanding contributions to solar science.
    Robert H. Olley / Quondam Physics Department / University of Reading / England