Ion Larmor radius effects in collisionless reconnection

The nonlinear evolution of collisionless magnetic field line reconnection is investigated numericallyin plasma regimes where the effects of the electron and ion temperatures are important. These effects modifythe structure of the current and vorticity layers that are formed during the onset of the reconnection instability.The results of investigations in a two-dimensional periodic configuration including ion Larmor radiuseffects to all orders are presented and compared with the results obtained in regimes with a large sound Larmorradius. It is found that, while the roles of the sound Larmor radius and the ion Larmor radius are interchangeableas far as the nonlinear reconnection rate is concerned, the structure of the vorticity and current density layers isdifferent in the two cases.