The current system generated by the PORCUPINE artificial ion beam in the ionospheric background plasma

The injection of a heavy ion beam into the magnetized ionospheric plasma during the PORCUPINE experiment showed that the beam is electrically depolarized while the electric current is attenuated by only 10%. This stresses the importance role of the ambient ionospheric plasma background and raises the question of how the beam current closes. A theoretical model for the development of the current system in the background plasma, based on the assumption of short-circuiting the current along the magnetic lines of force is presented. The model is supported by the experimental data of PORCUPINE. Results also suggest that plasma turbulence in the ion cyclotron modes is important in producing the anomalous resistivities required.