Effect of atmospheric exposure on secondary electron yield of inert metal and its potential impact on the threshold of multipactor effect

[Display omitted] •Secondary electron yield of inert metals increases with exposure time.•Surface adsorption layer consisting of carbon and oxygen elements results in the increase.•A two-layers secondary electron yield model is established and parameters of adsorption layer are obtained.•The increase of secondary electron yield can significantly reduce the multipactor threshold. The secondary electron emission (SEE) property of materials is closely related to the multipactor, which is one of the potential risk factors affecting the reliability of high power microwave components for space application. In the presented work, the influence of atmospheric exposure on the secondary electron yield (SEY) of the inert metal is investigated. It is found that the SEY increases gradually with exposing time, and the increase in SEY results from the surface adsorption layer consisting of carbon and oxygen elements. A two-layers SEY model is established to explain this evolution and obtain the corresponding parameters of the adsorption layer. Simulation on a C band impedance transformer shows that 45 days of exposure will result in a 7.5 dB decrease of multipactor threshold.