Mitigating Partial Discharge at Low Pressures Using Electrets for All-Electric Aircraft

High electric fields generate partial discharges (PDs) that degrade electrical insulators at an accelerated rate, posing a greater risk to system reliability. PD can be mitigated by neutralizing the high electric fields using electrets, which create their own electric fields independently. Our previous studies have explored the effectiveness of electrets in mitigating PD under recurrent, steep voltage pulses at high temperatures. However, the mitigation of PD using electrets at low pressures and high temperatures remains unexplored. In this study, we demonstrate that Parylene high temperature (HT) thin-film electrets effectively mitigate PD at low pressures and high temperatures. We measured PD under steep square voltage pulses with slew rates as high as 68.75 V/ns, at pressures as low as 20 kPa, and at temperatures up to $260~^{\circ }$ C. The results indicate that Parylene thin-film electrets can reduce PD magnitude and increase PD inception voltage (PDIV) in harsh electrical and thermal conditions at low pressures.