中文摘要：

真空中绝缘子表面的沿面闪络现象极大地限制了电真空设备的发展进程。为此,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,结合工程实际中经常采用圆台形绝缘结构,将其加工成不同角度的圆台形绝缘子,在ns脉冲电压下对试品进行了真空沿面耐电性能的测试,并分析了锥角对阴极三结合点处电场、表面电荷分布和初始电子运动轨迹的影响。结果发现：正锥角的闪络电压明显高于负锥角,而45°绝缘子的闪络电压最高。分析认为,锥角对绝缘子阴极三结合点处的电场和表面电荷分布影响很大,正锥角时阴极三结合点处的电场和表面电荷密度较小,而负锥角时两者较大,同时负锥角时电子的自由程变短,减小了电子与绝缘子碰撞时的能量。

英文摘要：

Surface flashover phenomena in vacuum often occur across 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.We introduced a kind of machinable ceramic with excellent machinable performance and good surface electrical capability for vacuum insulation system,and considered the commonly used truncated cone structure,machinable ceramic samples with different machined coning angles.Then we investigated the surface flashover voltage under nanosecond pulsed voltage in vacuum,and numerically simulated the electric field distributions and electron trajectory of different coning angles.The experimental results indicate that,the flashover voltage of truncated cone samples with positive coning angle is much higher than that of with negative coning angles,and the flashover voltage with 45°conical frustum is highest.It is considered that,the coning angle plays an important role in the electric field of cathode triple junction（CTJ） and surface charge distribution.When the coning angle is positive,the electric field of CTJ and surface charge distribution is smaller,and when the coning angle is negative,these values are higher,and also the free path of electrons is short and decreases energy of electrons colliding with insulator surface.