A Direct Measurement of Charge Density in the F2 Region

A measurement of the charge density in the F
2
region was made in 1962 with an ion trap mounted on an oriented satellite. Orbital monitoring of ionospheric characteristics continued for about four days. Current from collected ions, grid modulated by a triangular sweep voltage, indicated charge density, temperature, vehicle potential and some information on ion mass ratios. The current-measuring circuitry consisted of a hybrid electrometer followed by two amplifiers of similar circuit design. Determined ion kinetic temperatures were 1500°K and higher; ion concentrations varied from 5×10
³
to 10
⁶
ions/cm
³
over latitudes of 73°N to 73°S.