Electrical Breakdown Characteristics of Supercritical Trifluoroiodomethane-Carbon Dioxide (CF3I-CO2) Mixtures

Supercritical fluids (SCFs), as a new type of dielectric medium, combine highly desirable properties of gaseous and liquid dielectrics, most notably: low viscosity, high heat transfer capability, and high dielectric strength. This paper, for the first time, reports the results of breakdown experiments on the mixture of trifluoroiodomethane (CF
₃
I) and carbon dioxide (CO
₂
) under the supercritical conditions. Experiments were conducted in a 0.1 mm gap under a uniform electric field. The state of substance during experiments was obtained by the calculation from the equation of state (EoS), and by evaluating the optical appearance. The experiment result shows a dielectric strength of the supercritical CF
₃
I-CO
₂
mixture at an average of 278 kV/mm with a 10% CF
₃
I mass fraction. Our experiments also suggest that the dielectric behavior of this supercritical CF
₃
I-CO
₂
mixture manifests a discontinuity of the dielectric strength near the critical point. This paper indicates the suitability of using supercritical CF
₃
I-CO
₂
mixture for high power density applications.