Insulating Rod Operated in a Vacuum Vessel

This paper describes an improved insulating rod which is used to drive a moving contact contained in a vacuum vessel.The insulating rod used in this study was made of alumina ceramics with Fe-42Ni layer interposed between the ceramics and the connecting hardware, both of which are connected by brazing.The Fe-42Ni layer connected both ends of alumina ceramics formed into the shape of shield for reducing the electric field.The results of the dielectric test and the electric field calculation indicate that the creeping discharge on ceramics can be prevented by reducing the dielectric strength at the triple junctions.Properties of tensile strength influenced by the heat cycle are discussed. The decline of the tensile strength due to the heat treatment during manufacturing process can be reduced by adopting the rod design in which the stress intensity factor of the ceramics is around 0.7 for the fracture toughness.