Collisionless magnetic reconnection in a toroidal cusp

Fast collisionless magnetic reconnection is driven and observed in a toroidal magnetic cusp. For low values of the toroidal (guide) magnetic field, reconnection occurs without the formation of a macroscopic current channel. In the absence of a current channel, the measured plasma potential and poloidal flows are consistent with predictions based upon single particle theory. Only for large values of the toroidal magnetic field compared to cusp poloidal field is a current channel present. Also in this case single particle orbit theory provides a good description of the anomalous resistivity observed experimentally. (C) 2001 American Institute of Physics.