The Cylindrical Field Mill

摘要

A field-mill-type instrument is described which is especially suited to recording the atmospheric electric field form an airplane. The instrument measures the two components of the electric field vertical to its axis and rejects the component in the direction of the axis. This feature can be used to eliminate the influence of the airplane charge on the measurement of the atmospheric electric field so that also weak fields down to the order of two volts per meter can be recorded. Furthermore, each cylindrical field mill delivers two components of the electric field so that only two field mills of the cylindrical type are required to obtain all three components of the atmospheric electric field. Problems involving the correct place for mounting the field mill at the plane and the determination of the calibration factor are discussed. A brief analysis of the field records is given for the simple case of an electric charge of one sign in different positions to the airplane path. Ways are pointed out to either avoid strong electric fields during the flight or locate and penetrate them. (Author)