A magnetotail-like structure is modelled using a 2-dimensional, single-ion species, electromagnetic, Darwin (no displacement current), particle-in-cell (PIC) code, which is a modified version of that described by Hamilton and Eastwood [1982>. The modifications include new boundary conditions for the magnetic fields which allow a non-symmetrical topology to be modelled.

The work presented here is aimed at the construction and testing of a self-consistent 'steady-state' model. It is found that the model supports significant magnetic perturbations, arising as a consequence of cyclotron resonance interactions with ion beam-like features. When subjected to transient changes in the convection electric field, the model also exhibits field reconfiguration and particle responses reminiscent of near-Earth substorm behaviour. ¿ American Geophysical Union 1992