NEW UNITARY AND MULTICOMPONENT GASEOUS DIELECTRICS

Abstract

We continued our studies on unitary gases and gas mixtures in order to determine the effects of basic physical properties–such as electron attachment, electron scattering, and electron-impact ionization–on the breakdown strength of gaseous dielectrics. The uniform field DC breakdown strengths (relative to SF6 of 1) of some of the new unitary gases investigated are: 0.80, 1.32, 2.5, 2.5, 0.94, 0.41, 1.16, and 0.94 for C2F6, n-C4F10, 1,1,1-CC13CF3, 1,1,2-CC12FCC1F2, 0CS, 1,1,1-CH3CF3, C2C1F5, and 1-C3F6, respectively. Mixtures of electron attaching and electron thermalizing gases have been studied with emphasis on optimizing the contribution of the electron thermalizer to the dielectric strength of a multi-component gas mixture. Results are presented on mixtures containing electron attaching gases, such as SF6, 2-C4F6, and c-C4F8, and dipolar electron slowing-down components, such as CHF3, CH2F2, and 1,1,1-CH3CF3, which exhibited synergistic behavior. Similar behavior was exhibited by the binary mixtures SF6/1-C3F6, c-C4F8/1-C3F6, and SF6/0CS. These and earlier studies demonstrate the important role of electron scattering processes at subexcitation energies in effecting synergistic behavior in dielectric mixtures and in tailoring gaseous dielectrics for industrial application.