Analysis of secondary electron emission using the fractal method*

Abstract

Based on the rough surface topography with fractal parameters and the Monte–Carlo simulation method for secondary electron emission properties, we analyze the secondary electron yield (SEY) of a metal with rough surface topography. The results show that when the characteristic length scale of the surface, G, is larger than 1 × 10−7, the surface roughness increases with the increasing fractal dimension D. When the surface roughness becomes larger, it is difficult for entered electrons to escape surface. As a result, more electrons are collected and then SEY decreases. When G is less than 1 × 10−7, the effect of the surface topography can be ignored, and the SEY almost has no change as the dimension D increases. Then, the multipactor thresholds of a C-band rectangular impedance transfer and an ultrahigh-frequency-band coaxial impedance transfer are predicted by the relationship between the SEY and the fractal parameters. It is verified that for practical microwave devices, the larger the parameter G is, the higher the multipactor threshold is. Also, the larger the value of D, the higher the multipactor threshold.

Effects of O2 adsorption on secondary electron emission properties

“…The number of oxygen molecules desorbed was approximately 1.5×10 15 , which differs by approximately 55% from the above multilayer adsorption model's predictions. The following explains the difference between results.…”

“…With a coverage of about 0.90, the calculated number of O 2 adsorbing particles per cm 2 is 6.7×10 14 . Using the desorption during heating in an experiment, the gas change is determined to be 1.5×10 15 , which differs by 55% from the results from the multilayer adsorption model. This result can be explained by the fact that the metal surface is not perfectly flat and has slight depressions, resulting in a larger measurement result.…”

“…There have been multiple probability, statistical, and phenomenological models for simulating the scattering of SEs from metal. [15,16] In this subsection, a phenomenological model and Monte Carlo (MC) simulation method are used to simulate the SE emission process. [17] This method has the benefit of producing results that are as close as possible to the actual ones.…”

Secondary electron emission and photoemission from a negative electron affinity semiconductor with large mean escape depth of excited electrons

“…( 28) is a constant a little larger than 1. Therefore, since λ , B, and ε are independent of E po [39][40][41] and from Eqs. ( 2), (6), and ( 28), the ratio of δ H to δ h relative to a NEASLD can be expressed as…”

“…From Eqs. ( 2), (6), and (28), the fact that λ , B, and ε are independent of E po [39][40][41] and that K(E po , ρ, Z) at H ≥ E po ≥ h keV of a NEASLD can be approximated as a constant K(E po , ρ, Z) ChH , we can derive Eq. ( 28) with respect to E po and obtain the relationships among parameters of a NEASLD…”