Study of Breakdown Strength of Supercritical Carbon Dioxide

Supercritical carbon dioxide (scCO<inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</inf>) has garnered significant attention due to its excellent insulating strength and transport properties. Current international research primarily focuses on its breakdown characteristics near the critical point in micron-scale gaps. However, variations in power source types and polarities result in breakdown voltage data that lack broad reference significance, and there is a lack of discussion on voltage dispersion. For the same gap distance, slightly non-uniform electric fields exhibit similar DC, power frequency breakdown voltages (amplitudes), and 50% impulse breakdown voltages, with no significant polarity effect in asymmetric electrodes, indicating these data are valuable references. In this study, an independent supercritical discharge system was established using sphere-to-plate electrodes to generate a slightly non-uniform electric field with a non-uniformity coefficient of 0.99. Breakdown experiments were conducted at a 0.3 mm gap. The breakdown strength of scCO<inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</inf> was compared with common insulating media, and the regularity of its breakdown voltage dispersion was discussed. The results provide experimental data and a theoretical foundation for the application of scCO<inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</inf> in switching technology.