Dielectric Surface Flashover under Long-Term Repetitive Microsecond Pulses in Compressed Gas Environment

Area of Science:

• Electrical Engineering
• Plasma Physics
• Materials Science

Background:

• Multi-gap gas switches (MGS) are critical for high-power microwave (HPM) systems.
• Surface flashover has emerged as a significant insulation failure mechanism in MGS.
• The long-term deterioration of insulation under repetitive microsecond pulses (RMPs) remains poorly understood.

Purpose of the Study:

• To investigate the surface insulation lifetime (SIL) of dielectric materials under RMPs.
• To develop a predictive model for SIL under RMPs.
• To elucidate the mechanisms of insulation deterioration in MGS.

Main Methods:

• Conducted flashover experiments on various dielectric surfaces in SF6 and air atmospheres.
• Utilized parallel-plane electrodes for controlled flashover testing.
• Analyzed the influence of pulse repetitive frequency (PRF) and surface condition on SIL.

Main Results:

• Proposed an empirical formula for SIL prediction based on insulator work coefficient (λ).
• Observed accumulation effects influencing the relationship between E/p and pt_delay.
• Demonstrated decreased SIL recovery with increased PRF and exacerbated surface deterioration after successive flashovers.

Conclusions:

• The flashover path is critical for surface insulation performance under RMPs, driven by photoemission from ultraviolet (UV) radiation.
• Reducing surface paths is essential for future MGS designs.
• Improvements in surface insulation are necessary to mitigate flashover failures.