Paper SS-TuP13
Secondary Electron Yield for As-Received, Electrodeposited, and Crystalline Silver Surfaces

Tuesday, October 19, 2010, 6:00 pm, Room Southwest Exhibit Hall

Silver electroplating is commonly used to provide low electrical loss characteristics for RF and microwave devices. These RF devices can also be susceptible to multipactor discharge, a resonant electron phenomenon that relies on electron density growth by secondary electron emission. The secondary electron yield (SEY) can determine whether a multipactor discharge can form; therefore, understanding SEY variations in silver surfaces is necessary for accurate multipactor breakdown prediction. In this work, SEY is measured for a variety of silver surfaces using a retarding potential method. Starting with as-received silver with no specific surface preparation, SEY values are shown to be considerably increased due to adsorbed gases on both bulk and electrodeposited silver substrates. Auger analysis was performed to determine the contaminant layers, as it is these technical silver surfaces that are realistic for space hardware where in-situ surface conditioning is not possible. Additional SEY measurements were performed on both polycrystalline and single crystal silver surfaces to determine the effect of the crystalline orientation on the SEY. Different crystallographic orientations at the surface of the electrodeposit may arise due to differences in plating variables such as bath chemistry, electrode geometry and localized current density. These measurements serve to better understand possible improvements in plating processes to minimize secondary electron emission and multipactor risk. Lastly, the effect of baking and multipactor conditioning on silver SEY is presented. Formation of thin carbon films are observed as a result of multipactor exposure, and x-ray photoelectron and Raman spectroscopy film analysis results are presented.