Magnetic reconnection is a topological rearrangement of magnetic field that converts magnetic energy to plasma energy. Astrophysical flares, from the Earth’s magnetosphere to γ -ray bursts and sawtooth crashes in laboratory plasmas, may all be powered by reconnection. Reconnection is essential for dynamos and the large-scale restructuring known as magnetic self-organization. We review reconnect...

Magnetic reconnection is an important process providing a fast conversion of magnetic energy into thermal and kinetic plasma energy. In this concern, a key problem is that of the resistive diffusion region where the reconnection process is initiated. In this paper, the diffusion region is associated with a nonuniform conductivity localized to a small region. The nonsteady resistive incompressib...

We diagnose local properties of magnetic reconnection during a sawtooth crash employing the three-dimensional toroidal, extended-magnetohydrodynamic (MHD) code M3D-C. To do so, we sample simulation data in the plane in which reconnection occurs, the plane perpendicular to the helical ( ) ( ) = m n , 1, 1 mode at the q=1 surface, where m and n are the poloidal and toroidal mode numbers and q i...

Magnetic reconnection is a fundamental process in plasma physics, which involves the often explosive release of magnetically stored energy in both space and laboratory plasmas. In order for this sudden release of energy to occur, there must be a period of slow reconnection, in which magnetic stress accumulates in the system, followed by a quick transition to fast reconnection. The question of w...

We examine the effect of weak, small scale magnetic field structure on the rate of reconnection in a strongly magnetized plasma. This affects the rate of reconnection by reducing the transverse scale for reconnection flows, and by allowing many independent flux reconnection events to occur simultaneously. Allowing only for the first effect and using Goldreich and Sridhar’s model of strong turbu...

By using the method presented by Isobe et al. (2002), the non-dimensional reconnection rate vin/vA has been determined for the impulsive phase of three two-ribbon flares, where vin is the velocity of the reconnection inflow and vA is the Alfvén velocity. The non-dimensional reconnection rate is important to make a constraint on the theoretical models of magnetic reconnection. In order to reduce...

Magnetic reconnection is a driving engine of solar flares, stellar flares, and quite probably bursty events in high-energy astrophysical sites. The reconnection process is driven by a small-scale “dissipation region” surrounding the reconnection point (X-point), at which a plasma ideal condition breaks down. Recently, kinetic particle-in-cell (PIC) simulations have revealed that the electron id...

For understanding the structure of an MHD-scale Kelvin-Helmholtz Instability (KHI) in a non-linear stage, we have performed two-dimensional two-fluid simulations including finite electron inertial effects. In the twofluid system, magnetic reconnection occurs spontaneously because the ’frozen-in’ condition can be broken by the electron inertial effects. When an MHD-scale velocity shear exists, a...

Spontaneous acceleration of ions to suprathermal energies is observed during magnetic reconnection in the Mega-Ampere Spherical Tokamak (MAST). A high-energy tail is observed in the ion-distribution function following each internal reconnection event in Ohmic discharges. This phenomenon is explained in terms of runaway ion acceleration in the electric field induced by the reconnection.

Separatrix reconnection in the standard nontwist map is described, including exact methods for determining the reconnection threshold in parameter space. These methods are implemented numerically for the case of odd-period orbit reconnection, where meanders (invariant tori that are not graphs) appear. Nested meander structure is numerically demonstrated, and the idea of meander transport is dis...