Title:  Supercritical Fluids Insulation for High Power Density Applications

Committee: 

Dr. Graber, Advisor       

Dr. Steffes, Chair

Dr. Mourigal

Abstract:

The objective of the proposed research is to further the fundamental understanding of dielectric properties of supercritical fluids (SCFs), especially near the critical point. For the preliminary work, the electron kinetic process and Boltzmann analysis are conducted on carbon dioxide (CO2) and ethane (C2H6) to investigate their dielectric properties. The breakdown behavior of the pure SCF and its mixtures such as CO2 and C2H6 mixtures are found and demonstrated experimentally in the uniform field. Upon the preliminary work, investigations on dielectric properties of more promising candidate SCFs and mixtures, such as trifluoroiodomethane (CF3I), octafluorocyclobutane (C4F8), and their mixtures, will be conducted theoretically and experimentally. An improved analytical model that combines the electron kinetics theory and the unique microscopic property of SCFs, also considers the mean free path of electrons, will be developed. The proposed model will not only provide an accurate estimation of the breakdown characteristics by analyzing the mean free path of electrons and the cluster size of SCFs but also give a quantitative evaluation on the critical anomaly of electric discharge in SCFs. Fundamental understanding of dielectric properties of SCFs is expected to enable the design of numerous applications that require high power density, spanning from particle accelerators over x-ray radiography and radiotherapy to electrical power systems.