The topology of guiding center orbits in a linear magnetic cusp

Particle orbits for a linear magnetic cusp configuration, characteristic for magnetic reconnection, are analyzed within the guiding center approximation. A class of particle orbits encircling the magnetic X-line is identified and the orbit phase space partition is obtained and characterized as a function of dimensionless parameters controlling the orbit topology. The large majority of particles are found to be trapped in the direction of the X-line implying large neoclassical corrections to the plasma resistivity. This may be the key in explaining the high rates of collisionless magnetic reconnection observed in nature. (C) 2001 American Institute of Physics.