Astronomy and Astrophysics – Astrophysics
Scientific paper
Dec 1999
adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=1999ptep.proc..182v&link_type=abstract
Plasma Turbulence and Energetic Particles in Astrophysics, Proceedings of the International Conference, Cracow (Poland), 5-10 Se
Astronomy and Astrophysics
Astrophysics
2
Scientific paper
We discuss a generic mechanism for fast reconnection based on a small level of field stochasticity. The presence of noise boosts the reconnection rate in two ways. First, individual field lines enter and leave the reconnection zone on length scales which are much shorter than the transverse scale of the reconnection zone. Second, the reconnection layer involves the simultaneous reconnection of many independent flux elements. The net effect is that the reconnection speed is limited only by the ejection of plasma from a diffusion-broadened zone around the actual reconnection layer, and is independent of the plasma resistivity. Using Goldreich and Sridhar's model of strong turbulence in a magnetized plasma with negligible intermittency, we find that the reconnection speed in a turbulent medium is close to VAM2, where M is the ratio of the plasma turbulent velocity to the Alfven speed. Plausible alternative models of MHD turbulence change this result only slightly. The fraction of magnetic energy that goes directly into electron heating is of order RB-2/5M8/5 (where RB is the Lundquist number), so that the usual assumption that reconnection leads to ohmic heating does not hold. A somewhat larger fraction of the magnetic energy, ~RB-1/5M6/5, goes into high frequency Alfvén waves. The remainder of the energy liberated by reconnection goes turbulent motions on the scale of the reconnection sheet length. The current sheet remains thin, of order RB-3/5M-2/5 times the current sheet length. We claim that the qualitative sense of these conclusions, that reconnection is fast even though current sheets are narrow, is almost independent of the local physics of reconnection and the nature of the turbulent cascade. We comment briefly on the nature of magnetic flares.
Lazarian Alex
Vishniac Ethan T.
No associations
LandOfFree
Fast Reconnection in a Weakly Stochastic Field does not yet have a rating. At this time, there are no reviews or comments for this scientific paper.
If you have personal experience with Fast Reconnection in a Weakly Stochastic Field, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Fast Reconnection in a Weakly Stochastic Field will most certainly appreciate the feedback.
Profile ID: LFWR-SCP-O-1584527