Single ion motion in a reversed electric field structure

The standard expression for the polarization current assumes that a gyrating particle experiences the same electric field gradient over its entire orbit. For weak magnetic fields and small-scale potential structures this assumption may not be valid, especially for the heavier ions such as O+. Here the authors trace individual particle trajectories through a small-scale region of electric field reversal simulating an auroral arc. An earthward EXB drift is included. It is found, for example, that the topology of the ion orbits inside the arc dramatically changes when dE/dx > eB2/M which results in an effective heating of the ions. This condition is easily satisfied for O+ at L = 6. Potential implications of the results on auroral arc structure will be discussed. They will also consider the application of their results to crossed field electron devices