Investigation on capacitance variation under temperature and mechanical stress for the transfer capacitor in an electromagnetic pulse simulator

Stable capacitance in the transfer capacitor is crucial for ensuring a reliable output waveform from the high-altitude electromagnetic pulse simulator. Different types of environmental stress pose significant challenges for the performance and reliability of the outdoor simulator and its transfer capacitors. This paper presents a preliminary investigation on the effects of temperature and mechanical stress on both the capacitance of the transfer capacitor fabricated with the polypropylene film and the simulator's output waveform. Experiments reveal that the capacitance exhibits an approximately linear increase with temperature, reaching a maximum variation of 6.3% at 60 °C. It increases with the heating time and stabilizes after ∼1 h, and the capacitance change under thermal stress is reversible. The capacitance variation remains within 0.22% under the steady-state vibrational stress, whereas it decreases by ∼2.04% with an increasing number of hammer strikes. It is demonstrated that the fluctuation of capacitance caused by the thermal or mechanical stress would result in a deviation of the waveform for the simulator under the parameters in this study. These findings will enhance the understanding of the characteristics of the transfer capacitor under mechanical or thermal stress, thereby facilitating future optimization and rational maintenance of the capacitor with this structure.