Research on Insulation Problems Under Multishot Experiments in Electromagnetic Rail Launcher.

Insulators between conductive rails assume a leading role in electrical insulation and support fixation. Failure of insulating materials during continuous repetitive launches has been found in experiments, the performance changes of insulators will directly affect efficiency and lifetime in repetitive electromagnetic launcher system. Many factors may influence the insulating performance because of complicated working condition, such as strong pulse stress and high temperature. A multishot minor-caliber launcher was designed for the study of the insulating performance. The length of the launcher is 890 mm with a caliber size of 10~\text mm \times 10 mm. C-shaped aluminum alloy armatures and glass-reinforced polymer insulator G10 are used. The muzzle speed is above 2 km/s. After the multishot experiments, the surface topography and surface resistivity of the insulators were measured by megger and digital microscope. The experimental and testing results show that the surface resistivity of G10 reduces gradually with the increase of experiment times, also the surface resistivity of different locations changes. Some pits and cracks appear at individual locations on the G10 surface, the phenomena of resin wear and fiber exposed are observed. Metal deposition is also found on the insulator surface by different types at different positions. Surface flashover voltage is measured after ablation. [ABSTRACT FROM AUTHOR]