Significantly improved surface flashover characteristics of insulators in vacuum by direct fluorination

Seeking an insulator supporting high voltage and short pulsed-power electric field in vacuum is an important topic especially for some sophisticated equipments. The voltage breakdown along the surface of insulator in vacuum (i.e. surface flashover) is one of the most serious problems for insulators, and it greatly limits the overall performance of a vacuum-dielectric system. The improvement of surface flashover characteristics of insulators in vacuum become a significant challenge for the development of high voltage pulsed-power devices. Herein, we report a simple and convenient avenue to achieve the high surface flashover performance of high density polyethylene (HDPE) in vacuum based on direct fluorination technique. The physicochemical properties of the fluorinated HDPE (i.e., surface morphology, the chemical component, structure and dielectric capability) were comparatively investigated with the untreated HDPE. The surface flashover characteristics of HDPE in vacuum were mainly discussed. The performance of HDPE at different fluorination temperature was also investigated. The results demonstrated that the direct fluorination strategy developed in this work is an effective means to improve the surface dielectric capability of insulators in vacuum. It is believed to provide a novel possibility for the common insulators applied in high electric field vacuum environments.