New Research Reveals How Energy Dissipates Outside Earth’s Magnetic Field

College of Computer, Mathematical, and Natural Sciences

NASA mission, with help from a UMD physicist, is the first to observe a new type of turbulent magnetic reconnection, providing important clues about heating in the sun’s outer layersEarth’s magnetic field provides an invisible but crucial barrier that protects Earth from the solar wind—a stream of charged particles launched from the sun’s outer layers. The protective properties of the magnetic field can fail due to a process known as magnetic reconnection, which occurs when two opposing magnetic field lines break and reconnect with each other, dissipating massive amounts of energy and accelerating particles that threaten air traffic and satellite communication systems. 
Just outside of Earth’s magnetic field, the solar wind’s onslaught of electrons and ionized gases creates a turbulent maelstrom of magnetic energy known as the magnetosheath. While magnetic reconnection has been well documented closer to Earth, physicists have sought to determine whether reconnection also happens in this turbulent zone.
A new research paper co-authored by James Drake, a University of Maryland Distinguished University Professor of Physics, suggests that the answer to this question is yes. The observations, published in the May 10, 2018 issue of the journal Nature, provide the first evidence of magnetic reconnection occurring at very small spatial scales in the turbulent magnetosheath. However, unlike the reconnection that occurs with the Earth’s magnetic field, which involves electrons as well as ions, turbulent reconnection in the magnetosheath involves electrons alone. 
“We know that magnetic energy in churning, turbulent systems cascades to smaller and smaller scales. At some point that energy is fully dissipated. The big question is how that happens, and what role magnetic reconnection plays at such small scales,” Drake said. “This study shows that reconnection indeed can happen at the electron scale, with no ions involved at all, suggesting that reconnection may help dissipate magnetic energy at very small scales.” 
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