Fast collisionless magnetic reconnection: Fluid regime and kinetic effects

Collisionless magnetic ¢eld line reconnection exhibits important similarities under widely di¡erent physical conditions, ranging from the magnetohydrodynamic regime, of interest for space and high temperature magnetically con¢ned plasmas, to the electron-magnetohydrodynamic regime, of interest for the interaction of ultraintense, ultrashort laser pulses with a plasma. Analytical and numerical results are presented that illustrate the nonlinear evolution of the reconnection instability in a two dimensional con¢guration with a neutral line in fluid and in kinetic plasma regimes. The importance of plasma anisotropy is stressed for the case of laser plasma interaction.