AGU journal highlights -- Sept. 6, 2007( During solar flares and coronal mass...)
During solar flares and coronal mass ejections the Sun's magnetic field is carried by the solar wind to the rest of the solar system. The solar wind smashes into the Earths magnetosphere, causing field lines in both systems to break and rejoin at a current sheet. Whether this magnetic reconnection process is determined by dynamics at large or small scales is heatedly debated. Kuritsyn et al. study reconnection through laboratory experiments and find that the reconnection rate is a function of the plasma parameters at both large (system-wide) and small (local) scales. At the local scale the rate that charged particles collide with themselves governs the observed reconnection. When local collision rates are lowered, the current sheet is shortened and the effective dissipation is enhanced, both of which increase the reconnection rate. At the global scale, when collision rates are fixed, the current sheet length increases along with the global size, effectively lowering the reconnection rate.
Title:
Effects of global boundary and local collisionality on magnetic reconnection in a laboratory plasma
Authors:
A, Kuritsyn: Center for Magnetic Self-Organization in Laboratory and Astrophysical Plasmas, and Department of Physics, University of Wisconsin, Madison, Wisconsin, U.S.A;
H. Ji, S. P. Gerhardt, Y. Ren, and M. Yamada: Center for Magnetic Self-Organization in Laboratory and Astrophysical Plasmas, and Princeton Plasma Physics Laboratory, Princeton, New Jersey, U.S.A.
Source:
Geophysical Research Letters (GRL) paper 10.1029/2007GL030796, 2007, http://dx.doi.org/10.1029/2007GL030796
12. Evidence for interhemispheric coupling between the stratosphere and the mesosphere
Air circulation in the mesosphere, a region of the atmosphere between 50 and 90 kilometers (31 and 56 miles) above the Earth's surface, is driven by upwelling and cooling at the summ
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| Contact: Peter Weiss pweiss@agu.org 202-777-7507 American Geophysical Union Source:Eurekalert |
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