Publication Date:
2015-01-16
Description:
The linear behavior of plasmoid instability in double current sheet configurations, namely, double plasmoid mode (DPM), is analytically and numerically investigated within the framework of a reduced magnetohydrodynamic model. Analytical analysis shows that if the separation of double current sheets is sufficiently small [ κ x s ≪ κ 2 / 9 S L 1 / 3 ], the growth rate of DPMs scales as κ 2 / 3 S L 0 in the non-constant- ψ regime, where κ = k L C S / 2 is the wave vector measured by the half length of the system L C S / 2 , 2 x s is the separation between two resonant surfaces, and S L = L C S V A / 2 η is Lundquist number with V A and η being Alfven velocity and resistivity, respectively. If the separation is very large [ κ x s ≫ κ 2 / 9 S L 1 / 3 ], the growth rate scales as κ − 2 / 5 S L 2 / 5 in the constant- ψ regime. Furthermore, it is also analytically found that the maximum wave number scales as x s − 9 / 7 S L 3 / 7 at the transition position between these two regimes, and the corresponding maximum growth rate scales as x s − 6 / 7 S L 2 / 7 there. The analytically predicted scalings are verified in some limits through direct numerical calculations.
Print ISSN:
1070-664X
Electronic ISSN:
1089-7674
Topics:
Physics
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