Influence of the Temperature of the Deionized Water on the Sensitivity of D-Dot Sensor

Differential-output D-dot sensor is indispensable to monitor the performance of the pulsed power facility. The sensitivity of the D-dot monitor is determined by the capacitance of the sensor’s high-voltage arm, which is dependent on the temperature of the dielectric within the measured component. Herein, the influence of the temperature on the sensitivity of the D-dot monitor mounted in a water-insulated transmission line is investigated by experiments and confirmed by the transient electromagnetic (EM) simulation. The amplitude–frequency response properties of the D-dot sensor under different temperatures of the deionized water are measured. The experimental results demonstrate that the capacitance of the D-dot sensor’s high-voltage arm decreases almost linearly with respect to the temperature and the sensitivity increases by about 9.7% when the temperature raises from 9.4 °C to 28.3 °C. We have also calculated the capacitance of the D-dot monitor’s high-voltage arm by the transient EM simulation at a specific relative permittivity of the water medium. The relative permittivities of the water under different temperatures are acquired, which are very close to the results from the previous empirical formula. The approach presented herein is readily adapted to any liquid dielectrics and it is also a novelty for the measurement of the relative permittivity of liquid dielectrics.