An effective reduction on secondary electron emission yield of gold coated surfaces by laser etching

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Multipactor is a frequent discharging phenomenon for space high-power microwave components, and this detrimental effect is mainly induced by secondary electron emission (SEE) and electron resonance in vacuum. Plenty of researches have verified that suppressing SEE is an efficient approach to mitigate the multipactor. Therefore, low SEE yield surfaces are urgently needed for mitigating the multipactor in the field of space science. In the past few decades, a number of technics have been developed to acquire low SEE yield surfaces, including surface coating, surfaces roughening, depositing coessential nanostructure, etc. Laser etching has been partly reported to be an advisable way to construct micro- or nano-structure on some materials’ surfaces, and able to further suppress the SEE yield. Whereas, employing laser etching to obtain the SEE yield reduction on gold coated surfaces is rarely investigated. In this work, by using the laser etching technic, we fabricate four micro hole arrays and three orthogonal groove arrays with various porosities and aspect ratios, and we also characterize their three-dimensional and accurate two-dimensional morphologies. In addition, we investigate the dependence of SEE yield on surface morphology. Experimental results indicate that the laser etched microstructures can effectively suppress the SEE yield from gold coated surfaces, and the suppression levels on SEE yield of these samples are superior to those of many other low SEE yield technics. Furthermore, experiments reveal that the ability to suppress the SEE yield is positively related to the porosity and aspect ratio, as well as that the porosity influences SEE yield more strongly than the aspect ratio does. To theoretically verify the experimental phenomena, we utilize the Monte Carlo method combining with the SEE phenomenological model and the electron trajectory tracking algorithm, to simulate the SEE characteristics of the fabricated microstructures. And the simulation results can qualitatively explain the experimental phenomena. This work digs out an advisable method to sharply reduce the SEE yield from gold coated surfaces by laser etching, which is of considerable importance for exploiting the low SEE yield surface engineering in space microwave systems, and for improving the performance of the space microwave components with gold coated surface.