Fast collisionless magnetic reconnection: Fluid regime and kinetic effects

Collisionless magnetic ¢eld line reconnection exhibits important similaritiesunder widely di¡erent physical conditions, ranging from the magnetohydrodynamicregime, of interest for space and high temperaturemagnetically con¢ned plasmas, to the electron-magnetohydrodynamicregime, of interest for the interaction of ultraintense, ultrashort laser pulseswith a plasma. Analytical and numerical results are presented that illustratethe nonlinear evolution of the reconnection instability in a two dimensionalcon¢guration with a neutral line in fluid and in kinetic plasma regimes.The importance of plasma anisotropy is stressed for the case of laser plasmainteraction.