Simultaneous measurements of electric fields and upward moving ionospheric ions from the Viking satellite show that upward escape of ionospheric ions in the tens of eV to tens of keV energy range occurs together with low-frequency electric fluctuatons, LEFs (frequencies less than ≈1 Hz). Upward flowing ions are observed when the electric field fluctuations are sufficiently strong in the altitude range ≈2000--13,500 km covered by Viking. Furthermore, the temperature of the upflowing ions is found to be well correlated with the power spectral density (PSD) of the LEFs. This suggests a conversion of electric field energy into thermal energy. A good correlation between the ion temperature and the wave power in the electrostatic ion cyclotron (EIC) frequency range is also found. However, the heating/acceleration and the corresponding escape of ionospheric ions is believed to be primarily caused by LEFs, first because of the much higher power in the LEFs than the power in the EIC frequency range and second because the PSD clearly peaks below ≈1 Hz while the frequency range of the EIC mostly appears as a monotonic tail or ''background'' of an overall PSD increase at low frequencies.

Electric fluctuations, and the associated escape of ionospheric ions, are mainly observed inside or above the acceleration region. Below the acceleration region, predominantly downward accelerated electrons are observed. This can be understood as a short-circuiting of electric fluctuations by the plasma in the topside ionosphere where the plamas a is gaining kinetic energy by the electric field. Thus the electric energy from the source/dynamo in the outer magnetosphere is dissipated in the topside layer of the ionosphere, causing an acceleration and escape of ionospheric plasma. Ion conics with an ion heating up to several keV are associated with the strongest electric fluctuations (up to ≈103 (mV/m)2/Hz), while low-energy ion beams in general are connected with somewhat smaller electric fluctuations. Spatial or temporal electric fluctuations are expected to increase the magnetic moment of the local plasma via a transverse equation velocity gain acceleration process. This is consistent with the observed electric field power spectrum usually peaking below both the O+ and H+ gyrofrequency. ¿ American Geophysical Union 1990