Energetics of forced magnetic reconnection in a visco-resistive plasma

The rate of energy dissipation provided by the ongoing magnetic reconnection in a force-free magnetic field is investigated in the framework of visco-resistive magnetohydrodynamics (MHD). It is shown that viscous effects are important even under small magnetic Prandtl number Pm ≡ν/η, namely for Pm <S-25, where ν and η are the plasma viscosity and resistivity, respectively, and S≫1 is the Lundquist number of a highly conducting plasma. Various regimes of plasma heating, which are determined by the nondimensional parameters Pm, S, and ω τA, are identified, where τA is the Alfv́n transit time of the magnetic configuration and ω is the frequency of an external driver. © 2005 American Institute of Physics.