Universal Formula for Secondary Electron Yield of Metals at High Electron Energy and Incident Angle θ

Abstract

On the basis of the main physical processes of secondary electron emission, the relationships among the incident energy (Wp0) of primary electrons, the number of secondary electrons (δPEθ) released per primary electron entering the metal at high electron energy and incident angle θ and incident angle (θ) are deduced. In addition, the relationship between the number of secondary electrons (δPE0) released per primary electron entering the metal at θ= 0° and Wp0 is determined. From the experimental results, the relationships among the ratio βθ (the subscript θ means the primary electron is incident at θ in this paper), the ratio at θ= 0° (β0) and θ are obtained. On the basis of relationships among δPEθ, δPE0, βθ, β0, backscattered coefficient ηθ, backscattered coefficient at θ= 0° (η0), secondary electron yield δθ, and secondary electron yield at θ= 0° (δ0), the universal formula for expressing δθ using δ0, ηθ, η0, and θ is deduced. The secondary electron yield calculated from this universal formula and the yields measured experimentally from aluminum and copper are compared. The results suggest that the proposed formula is universal for the estimation of secondary electron yields in the angle range of 0–80° and the energy range of 10–102 keV.