We present and discuss few examples of plasma observations made in ionosphere at ~700 km by CNES micro-satellite Demeter during magnetospheric and thunder-storms. The conjugated observations of onboard ion retarding & drift analysers and electric field antennas (both developed by the LATMOS team) together with remote optical imagers and VLF antennas allow to analyse the perturbations of the plasma parameters (ions composition, drift and field-aligned motion, temperature and density of thermal and suprathermal population) with respect to the variation of the field-aligned currents, the electron and proton precipitation, the power and localisation of electric discharges.