Reconnection of magnetic field lines in viscous conducting fluids

Abstract

In the formulation of steady hydromagnetic flows of a viscous conducting fluid, continuous solutions in similarity form are obtained which exhibit the topology of field line reconnection without the inclusion of discontinuity fronts. The properties of the flow support the assertion that magnetic merging can be mainly controlled by distant boundary conditions.

The generalized Ohm’s law in collisionless magnetic reconnection

“…The change o f magnetic field topology requires the breakdown of the "frozen-in" condition in ideal magnetohydrodynamics (MHD) equations. Most studies o f magnetic reconnection [Sweet 1958;Parker, 1957;Petschek, 1964;Sonnerup, 1970;Yeh and Axford, 1970;Priest and Forbes, 1986;Priest and Lee, 1991; are based on resistive MHD equations in which the resistivity is responsible for the breakdown o f "frozen-in" condition. In the resistive MHD equations, the resistivity is associated with Coulomb collisions of charged particles.…”

Finding reconnection lines and flux rope axes via local coordinates in global ion-kinetic magnetospheric simulations

“…We take the southward-IMF initial configurations of Hu et al (2009); Komar et al (2013) for a test case that has null lines, and who also provide analytical solutions for the magnetosphere using the methods by Yeh (1976). The current-free initial condition is not suitable to apply our method to, since we use the current density vector to define the handedness of our coordinate basis.…”

Formation of singularities in Hall magnetohydrodynamics

“…Among the cascade of simplifications which start from the Boltzmann equations for multi-species plasmas and eventually end in the system of classical magnetohydrodynamics (MHD) (Chen 1983), the system of Hall MHD remains one of the most useful. It has been proposed to explain fast magnetic reconnection (Shay et al 2001;Biskamp 2000) in order to avoid the shortcomings of the single fluid Sweet-Parker model (Sonnerup 1970;Yeh & Axford 1970). The problem of this is that in weakly collisional plasmas where the Spitzer resistivity is small, very thin current sheets are needed for resistive dissipation to be relevant.…”