Rheometry experiment of an electric field sensor for plasma wave observation

Observation of plasma waves is an important subject of a spacecraft observation. The waveforms of electromagnetic field observed by sensors aboard a spacecraft are converted to electric voltage and is sent to the Earth as a set of digital data. Therefore, to know the exact intensity of the electromagnetic field, an accurate calibration of the sensor is required. However, it is difficult to acquire the characteristics of an electric sensor in a ground test. For observation of the electric field component of the wave, a dipole antenna using a pair of wires (a wire antenna) is often used, and since the sensitivity must be assured at frequency of several kHz or below for plasma wave observation, the total length of the wire is very large, ranging from tens of meters to 100 m. The size of wire and the difficulty of reproduction for the space plasma environment make the ground test hard.