氧化铝陶瓷绝缘子真空沿面闪络过程中的陷阱机制

Traping and De-traping Process Resulting in the Alumina Surface Flashover in Vacuum

采用热刺激电流法(TSC)研究了不同烧结温度和掺有不同添加剂的氧化铝陶瓷的陷阱能级密度分布特性以及在负脉冲电压作用下的真空中表面带电和沿面闪络特性。研究发现,氧化铝陶瓷的陷阱分布与其真空中的表面带电和沿面闪络特性之间存在一定的内在联系,即材料中的陷阱密度越大,其表面电荷密度越高,且沿面闪络电压越低。上述结果表明,氧化铝陶瓷在真空沿面闪络过程中,除了电介质的二次电子发射作用外,载流子的入陷、脱陷机制也起着相当重要的作用。

Alumina ceramic samples prepared under different sintering temperatures and various additives were measured to indicate the trap density and trap energy located in alumina materials by thermally stimulated current（TSC）. The surface charges on alumina in vacuum after applying a negative pulse voltage（0.7/4μs） were measured, as well as flashover performances of the materials in vacuum. It is found that the trap energy level density distribution in alumina has a correlation with surface charges and flashover performances in vacuum. The higher is the trap density in the material, the higher is the surface charge density, and the lower is the flashover voltage on alumina surface. The trapping and de-trapping mechanisms of carriers play an important role during the development of the flashover processes, together with the secondary electron emission mechanism.