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Paper: High Lundquist Number Resistive MHD Simulations of Magnetic Reconnection: Searching for Secondary Island Formation
Volume: 444, 5th International Conference of Numerical Modeling of Space Plasma Flows (ASTRONUM 2010)
Page: 124
Authors: Ng, C. S.; Ragunathan, S.
Abstract: Recently, secondary island formation due to the tearing instability of the Sweet-Parker current sheet was identified as a possible mechanism that can lead to fast reconnection (less sensitive dependence on Lundquist number S) both in numerical simulations using Particle-in-Cell (PIC) method [Daughton et al. 2009], as well as using resistive magnetohydrodynamics (MHD) [Lapenta 2008; Bhattacharjee et al. 2009]. This instability is thought to appear when S is greater than a certain threshold. These recent results prompt us to perform more resistive MHD simulations of a basic reconnection configuration based on the island coalescence instability, using much higher resolutions and larger S. Our simulations are based on a fairly standard pseudo spectral code, which has been tested for accuracy, convergence, and compared well with codes using other methods [Ng et al. 2008]. In our simulations, formation of plasmoids were not found, except when insufficient resolution was used, or when a small amount of noise was added externally. The reconnection rate is found to follow the Sweet-Parker scaling when no noise is added, but increases to a level independent of S with noise, when plasmoids form. Latest results with S up to 2×105 will be presented.
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