Formulae for secondary electron yield and the ratio of the average number of secondary electrons generated by a single backscattered electron to that generated by a single primary electron
On the basis of the characteristic of secondary electron emission, the number of secondary electrons (δPEθ) released per primary electron entering metals in the incident energy (Wp0) range 10-102 keV and the incident angle (θ) range 0-89° was deduced. In addition, the number of secondary electrons released per primary electron entering metals at θ=0 (δPE0) was obtained. Based on the deduced δPEθ, the characteristic of the emission angle distribution of the backscattered electrons and the definition of βθ, the relationships among βθ, cosθ and the parameter x were given, where βθ is the ratio of the average number of secondary electrons generated by a single backscattered electron to that generated by a single primary electron entering the emitter at θ. Considering the relationship between δPEθ and δPE0 and the relationship between the secondary electron yields at Wp0=10-102 keV and θ=0-89° (δθ) and the secondary electron yields at θ=0(δ0), a universal formula for expressing δθ through δ0, the backscattered coefficient at θ (ηθ), the backscattered coefficient at θ=0(η0), cosθ and the parameter x were deduced. Further, the parameters x related to beryllium, uranium, aluminium and copper were computed with the deduced formula and experimental results; then, the formulae for expressing δθ from the four metals through δ0, ηθ, η0 and cosθ were obtained; and the relationships between βθ of the four metals and cosθ were found. The δθ calculated with the formulae and the yields measured experimentally were compared. Finally, it is concluded that the formulae for δθ and βθ from the four metals at Wp0=10-102 keV and θ=0-89° have been established, respectively.
Secondary electron yield; Emission angle distribution; Backscattered electron; Incident angle
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