The determination of ionospheric plasma drifts by a rocket-borne electrostatic flux meter

The briefly described theory of an electrostatic fluxrneter (ELV) exposed to the ionospheric plasma permits the determination of ion drift velocity from measured signals. Results of a rocket flight under twilight conditions are reported where electric fields and plasma drifts were measured by several independent methods (double probe field-meter, barium cloud experiment and ELV). A comparison between the results of the different instruments is given. Considerable deviations among the measurements are found as soon as the rocket is exposed to sunlight, where photoemission from the fieldplates of the ELV becomes important.