Rolling temperature effects on linear current range of secondary electron emission properties of an activated Cu–3.0Be alloy

Abstract

This study investigates the impact of hot rolling on the linear current range of the secondary electron yield (SEY) curve for activated Cu-3.0Be sheets. Analysis of the SEY curve tests revealed that the BeO layer exhibited a favorable linear dynamic range at 650 °C, spanning approximately 0–201 eV. SEM results indicated BeO layer rolled at 650 °C has a compact and smooth surface, while BeO layer rolled at 800 °C has a rough surface texture. The non-uniform surface morphology can hinder the emission or absorption of secondary electrons due to charge accumulation and enhanced electric field effect. BeO layer thickness was found to be 15-27 nm for samples rolled at 650 °C, while it was only 8-15 nm for those rolled at 800 °C. Furthermore, numerous dislocation lines were detected in the TEM images of samples rolled at 650 °C. These lines facilitate the diffusion of the Be element, leading to a thicker BeO layer following its activation. Excessively thin BeO layers can lead to collisions between excited secondary electrons and free electrons in the alloy substrate, resulting in reduced initial velocity and hindered progression to the next dynode at low voltages, which leads to a narrow linear range of current.