Speaker
Description
Magnetic turbulence has been suggested to be controlled either by Alfvénic dynamics or by magnetic reconnection, and the relative importance of these two mechanisms has remained an open question. In this work, we examine the physical processes that regulate the evolution of magnetic turbulence by means of numerical simulations. We consider maximally helical MHD turbulence in a magnetically dominated regime, and systematically vary the magnetic field strength, fluid viscosity, and magnetic diffusivity. Because magnetic helicity density is not conserved in non-ideal MHD, we use its decay behavior as a diagnostic to identify the dominant governing mechanism. We find that the turbulent evolution is consistent with the Sweet–Parker reconnection regime for Lundquist numbers in the range 10≲S≲100. While it has been suggested that the characteristic timescale of magnetic turbulence appears to be primarily determined by the Alfvén regime, our results suggest that reconnection appears to play a dominant role in governing magnetic turbulence.
| Other topic / keywords: | MHD turbulence |
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