Ionospheric ion flow velocities from measurements of the ion distribution function technique

A technique for sampling the ionospheric ion distribution function using a cylindrical plate electrostatic energy analyzer for the expressed purpose of detecting electric field-induced motions is presented. It is shown that data derived from a typical sounding rocket flight of this instrument may be used to determine unambiguously the ion flow velocity and that this technique is virtually unaffected by perturbing effects due to wake and sheath, which sometimes interfere with other related convective electric field measurements (e.g., double probes). Ion densities and temperatures may also be extracted from the data, although with somewhat less precision.