真空条件下介质窗表面微波击穿实验

Experimental studies on dielectric surface breakdown at vacuum conditions under high-power microwave excitation

介绍了介质表面真空微波击穿研究实验装置的设计以及介质表面刻凹槽实验。微波源为S波段速调管,中心频率2.86 GHz,脉宽1μs。为确保击穿发生在后端介质样品处,而前端用于和速调管源隔离的陶瓷微波窗不击穿,实验装置采用先分后合的方法,利用两个陶瓷窗,每个陶瓷窗传输总功率的一半。为了抑制三相点带来的效应,采用凹形的圆柱介质,三相点处于电场强度弱的位置,有效消除了三相点的影响。在此实验装置上做了表面刻凹槽实验,初步实验结果表明,与光滑表面击穿阈值相比较,刻凹槽可使功率容量提高2倍以上。

The HPM dielectric surface breakdown experiments under vacuum are conducted in a pillbox.For minimizing the effects of the dielectric/metal/vacuum triple point,a concave cylindrical dielectric is used.It is proved the triple point is ＂removed＂ from the breakdown location in experiments.It was confirmed by experiment that periodic grooves perpendicular to the major electric field can increase transmitted power,when compared with smooth dielectric geometries.