Single particle motion near a X point and separatrix

Abstract

The motion of a single particle near an X point or separatrix in given static axisymmetric electric and magnetic fields is studied. It is shown that large classes of particles are lost on a time scale given by the distance scale on which the fields vary divided by the thermal speed. In a low beta version of the problem the results are more specific and the classes of particles are described which are either lost or confined. A preliminary, simpler problem is also treated with model fields in rectangular geometry. Although the losses are similar, the orbits near the X point exhibit a more complicated structure in phase space. (C) 2004 American Institute of Physics.