Measurements of ion concentrations in the D-region of the ionosphere with a Gerdien condenser rocket probe

This report describes the development of a Gerdien condenser rocket system for measurements of ion concentrations in the ionospheric D-region. The Gerdien condenser and the instrumentation connected to it is separated from the rocket close to the top of the rocket trajectory, and the measurements are done during the descent with the instrumentation hanging under an inflatable parachute. Data from the first launchings at White Sands Missile Range indicate that the concentration of positive ions is of the order of 104 cm−3 and the concentration of negative ions is of the order 103 cm−3 in the height range 50–70 km. This indicates that heavy negative ions, which cannot be collected by the Gerdien condenser, most probably are present in the same height range. Heavy negative ions may be formed in chemical reactions or in clustering processes. Recombination to dust seems to be important below 50 km. This may be due to high dust concentrations above the launch site or dust layers from volcano eruptions observed at the time of the rocket firings.