Freja, the joint Swedish and German scientific satellite, has an orbit inclination that allows it to transverse the auroal oval tangentially and stay for minutes on field lines connected to the auroal energization region. One signature of the auroral energization process is the heating/ transverse energization of ionospheric ions. Associated with such transverse heating/energization of ionospheric ions is a depletion of cold plasma in the topside ionosphere. We have studied several Freja passes at ~1700 km altitude with long time periods of plasma depletion and transverse ion acceleration. Inside these depletion regions the density may decrease by more than two orders of magnitude (from 1000 to ≈10 cm-3). This suggests that transverse ion heating is indeed a very strong mechanism for plasma density depletion in the topside ionosphere. ¿ American Geophysical Union 1994