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| Titel |
Fast magnetic reconnection in thin current sheets: effects of different current profiles and electron inertia in Ohm's law. |
| VerfasserIn |
Fulvia Pucci, Daniele Del Sarto, Anna Tenerani, Marco Velli |
| Konferenz |
EGU General Assembly 2015
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 17 (2015) |
| Datensatznummer |
250108221
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| Publikation (Nr.) |
 EGU/EGU2015-7964.pdf |
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| Zusammenfassung |
| By examining sheets with thicknesses scaling as different powers of the Lundquist number S,
we previously showed (Pucci and Velli, 2014) that the growth rate of the tearing mode
increases as current sheets thin and, once the inverse aspect ratio reaches a scaling
a/L = S-1/3, the time-scale for the instability to develop becomes of the order of the Alfvén
time. That means that a fast instability sets in well before Sweet-Parker type current sheets
can form. In addition, such an instability produces many islands in the sheet, leading to fast
nonlinear evolution and most probably a turbulent disruption of the sheet itself. This
has fundamental implications for magnetically driven reconnection throughout the
corona, and in particular for coronal heating and the triggering of coronal mass
ejections.
Here we extend the study of reconnection instabilities to magnetic fields of grater
complexity, displaying different current structures such as, for example, multiple or
asymmetric current layers. We also consider the possibility of a δ′ dependence on
wave-number k-p for different values of p, studying analogies and variations of
the trigger scaling relation a/L ~ S-1/3 with respect to the Harris current sheet
equilibrium.
At large Lundquist numbers in typical Heliospheric plasmas kinetic effects become more
important in Ohm’s law: we consider the effects of electron skin depth reconnection, showing
that we can define a trigger relation similar to the resistive case. The results are important to
the transition to fast reconnection in the solar corona, solar wind, magnetosphere as well as
laboratory plasmas.
F. Pucci and M. Velli, "Reconnection of quasi-singular current sheets: the “ideal" tearing
mode" ApJ 780:L19, 2014. |
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