Failure Analysis of a High Voltage Feedthrough of Indus-2 Synchrotron Radiation Source

In this paper, a failure analysis of a high voltage feedthrough of the Indus 2 synchrotron radiation source which brought about venting of the vacuum chamber is discussed. A detailed failure analysis demonstrated that the main cause responsible for the failure of the feedthrough was high humidity in the atmosphere surrounding the feedthrough assembly, which resulted in the corrosion of CuSil braze filler alloy at the ground terminal and also caused flashover between positive (+) and ground terminals. Thermal cycling of the insulator due to flashover resulted in spalling of glazed surface layer and assisted crack propagation from the flashover-generated surface defects. The remedial measures recommended to avoid similar failure include: thorough cleaning of feedthrough and its connectors before installation, use gasket-type sealing in the protective cover of the connector on the air side, use of metallic tubes in place of polyurethane cooling water tubes and design change of feedthrough to shift brazed joint to vacuum side.