多层均压结构可加工陶瓷真空沿面耐电特性的实验与仿真研究

Experimental and Simulation Investigation on Surface Electric Withstanding Characteristics of Machinable Ceramic With Multiple Layers in Vacuum

真空中沿固体绝缘材料表面的闪络电压通常远低于绝缘材料自身及相同长度真空间隙的击穿电压,这一现象极大地限制了高压真空设备的发展。将一种具有优良可加工性能和良好耐电性能的可加工陶瓷引入真空绝缘领域,结合工程实际中的绝缘堆结构,加工制作了多层均压结构;在纳秒脉冲电压下对不同多层均压结构的样品进行了真空沿面耐电性能的测试,并分析了不同均压结构对样品沿面电场和电子运动轨迹的影响。结果表明:多层均压结构样品的耐压强度要高于圆柱形样品,且其闪络场强随着绝缘层与金属层比例的增大有增大的趋势,径向电场随该比例的增大而减小;使用圆台形绝缘子组成多层均压绝缘结构时,电子难以与样品表面发生碰撞,闪络的稳定性得到了一定程度的提高。

Surface flashover phenomena in vacuum often occur along the insulator,with its onset flashover voltage much lower than the breakdown voltage of either the insulator or the vacuum gap with the same length,so it seriously limits the development of high voltage electro-vacuum devices.Introducing a kind of machinable ceramic（MC） with excellent machinable performance and good surface dielectrical capability into vacuum insulation system,and considering the commonly used insulation stack structure,multiple layers machinable ceramic samples were established.Their surface flashover voltage were investigated under nanosecond pulsed voltage in vacuum,and the surface electric field distributions and electron trajectory in different structure were simulated.The experimental results indicate that,the flashover voltage of multiple layer insulators is better than that of the cylinder,and it improves with the increase of ratio of insulation to metal（I/M）,the radial electric field of multiple layer insulators decreases with the increase of I/M.The flashover stability of truncated cone MC multiple layer insulators is better than that of truncated cone MC with the same angle,and the electrons are not easy to impact the surface of samples.