Electric field measurements in the magnetosphere by the electron beam boomerang technique

This paper describes the outline of the electron beam boomerang experiment carried out on the Geotail spacecraft. The experiment uses an electron beam artificially emitted from the satellite to measure the three dimensional electric field as well as the magnitude of the magnetic field. Unlike the Geos electron beam experiment, The boomerang experiment measures the time of flight of the electron beam returning to the spacecraft, which improves the measuring accuracy significantly.