Development of a fast impedance probe for absolute electron density measurements in the ionosphere

The design of a digitally controlled impedance probe for the fast absolute measurement of the ionospheric plasma density aboard a sounding rocket is described. Instrument performance is tested in a large plasma chamber. The first results from two flights within the DEOS-campaign are reported, and discussed with respect to spatial resolution and wake effects. The resulting density profiles have the same shape as ground-based ionosonde measurements. The in situ impedance probe measurements yield absolute electron densities that are lower by a factor of 1.5-2.