Calibration of field-mill instrument for measuring DC electric field

The measurement of DC electric field is of great significant. This paper introduces the structure and working principle of the field-mill instrument firstly. Then the calibration method of field-mill instrument in a uniform space-charge-free field is introduced and the error in the calibration is studied by numerical calculation. The calibration coefficient is corrected to be more accurate afterwards. At last, the interaction between the field-mill instruments is discussed. By means of numerical calculation, the shortest distance between two field-mill instruments which can control the measurement error less than 5% is put forward.