MIT: Study Sheds Light on Turbulence in Astrophysical Plasmas

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MIT: Study Sheds Light on Turbulence in Astrophysical Plasmas

Post by bystander » Sat Dec 02, 2017 3:36 pm

Study Sheds Light on Turbulence in Astrophysical Plasmas
Massachusetts Institute of Technology | 2017 Dec 01
[img3="Magnetic reconnection is a complicated phenomenon that Nuno Loureiro, an associate professor of nuclear science and engineering and of physics at MIT, has been studying in detail for more than a decade. Loureiro’s understanding of this process of magnetic reconnection has provided the basis for the new analysis that can now explain some aspects of turbulence in plasmas. Image Credit: NASA/GSFC/SDO"][/img3][hr][/hr]
Plasmas, gas-like collections of ions and electrons, make up an estimated 99 percent of the visible matter in the universe, including the sun, the stars, and the gaseous medium that permeates the space in between. Most of these plasmas, including the solar wind that constantly flows out from the sun and sweeps through the solar system, exist in a turbulent state. How this turbulence works remains a mystery; it’s one of the most dynamic research areas in plasma physics.

Now, two researchers have proposed a new model to explain these dynamic turbulent processes. ...

“Naturally occurring plasmas in space and astrophysical environments are threaded by magnetic fields and exist in a turbulent state,” Loureiro says. “That is, their structure is highly disordered at all scales: If you zoom in to look more and more closely at the wisps and eddies that make up these materials, you’ll see similar signs of disordered structure at every size level.” And while turbulence is a common and widely studied phenomenon that occurs in all kinds of fluids, the turbulence that happens in plasmas is more difficult to predict because of the added factors of electrical currents and magnetic fields. ...

Loureiro and Boldyrev found that magnetic reconnection must play a crucial role in the dynamics of plasma turbulence, an insight that they say fundamentally changes the understanding of the dynamics and properties of space and astrophysical plasmas and “is indeed a conceptual shift in how one thinks about turbulence,” Loureiro says.

Existing hypotheses about the dynamics of plasma turbulence “can correctly predict some aspects of what is observed,” he says, but they “lead to inconsistencies.” ...

Collisionless Reconnection in Magnetohydrodynamic and Kinetic Turbulence - N. F. Loureiro, S. Boldyrev
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