Analysis on the Dielectric Breakdown Characteristics of Bas-Based Glass Insulators Operated in Cryogenic Conditions

초록

As the demand for cryogenic pumps grows across various sectors, the use of cryogenic feedthrough has expanded accordingly. In a cryogenic condition at 100 K, phenomena such as thermal contraction, gas bubble generation, and degradation of dielectric strength are commonly encountered. Ensuring reliable operation under these conditions requires understanding the thermal and dielectric properties of insulating materials and maintaining adequate insulation performance. Barium aluminosilicate glass insulators exhibit low coefficient of thermal expansion, high manufacturing precision, and stable hermetic sealing with metals, making them well-suited for cryogenic feedthrough applications. However, previous research on cryogenic insulation has mainly focused on polymer-based synthetic insulators or thermal properties of glass, and studies on the dielectric strength of glass under cryogenic conditions remain limited. Therefore, this study aims to evaluate the dielectric properties of BAS glass insulators under cryogenic conditions. This paper conducted creepage discharge experiments on glass insulating specimens under cryogenic conditions to obtain basic data for cryogenic device design. BAS glass was used, and specimens with creepage distances of 11, 9, and 7 mm were tested under AC voltage at pressures of 1 and 3 bar. The breakdown voltage was analyzed according to pressure and creepage distance. The results show that breakdown voltage increases with pressure and creepage distance, providing useful guidelines for the application of glass insulators in cryogenic feedthroughs.

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