Do ring current ions set the outer plasmasphere in motion?

GEOS-2 experiments have observed on a regular basis the transition from teh plasmasphere to the trough revealing a more tenuous and energetic population. This transition occured typically between 18 and 21 h local time under quiet geomagnetic conditions. On the plasmasphere side of the transition, large electric fields of several mV/m, mainly in the duskward direction, were observed. The present statistical results, over one year of data, assess clearly the mean magnitude and direction of these electric fields in relation to the boundary between these two plasma regimes under quiet geomagnetic conditions. The possibility of ring current energetic ions loosing part of their energy to the plasmasphere and accelerating this plasma sunward will be discussed.