In order to restrain surface breakdown of dielectric window in HPM (High Power Microwave) devices, experimental research of surface breakdown suppression technology for PTFE is performed under an S-band HPM experimental system in this paper. Different suppression technologies are employed, such as surface polishing, surface notching and surface coating technologies, etc. Experimental results show that polishing treatment on dielectric surface can increase surface breakdown threshold. The surface grooves parallel to the direction of electric field can reduce surface breakdown threshold, while the grooves perpendicular to the direction of electric field can suppress surface breakdown, and the effect is influenced by the depth and width of groove. The surface breakdown experiment of TiN coating on PTFE surface is performed, and the results are also discussed. A new machinable ceramic material is proposed, and the main electrical characteristics of which are introduced. This new material will be promising as dielectric window material of HPM devices.
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