表面吸附层对空间金属二次电子发射影响的研究

Surface adsorption of metal is recognized as an important factor that prevents the enhancement of the micro-discharge threshold of spacecraft. However, little has been known so far about the dynamic process and mechanism of secondary electron (SE) emission (SEE) from metal with adsorption surface. Based on the current Monte Carlo model of electron scattering and emission, the aim of this project is therefore to develop a surface barrier model and Monte Carlo model for SEE from an adsorption surface. According to chemisorption force, surface barrier will be constructed to calculate the transmission coefficient by the first principles. The scattering processes of electrons and adsorbed molecules will be simulated by Monte Carlo method with the physical absorption mode developed by the Polanyi potential theory. Ionizing electrons caused by the collision between electron and adsorbed molecule will also be tracked as the original SEs. In order to verify the relevant models, SEE experiments of adsorption metal surfaces will be carried out in the ultrahigh vacuum. Some quantitative results about the relevance of the SE yield and barrier shape, height, adsorption quantity, thickness, density will be clarified clearly. This project will provide a new insight into a comprehensive understanding of adsorption surface influences on SEE. The expected results will also have great value in spacecraft fault prediction of micro-discharge event in our country.

表面吸附是制约航天器微放电阈值提高的重要因素，但目前对于表面吸附层对电子辐照金属二次电子发射动态过程及微观机理的影响仍缺乏了解。本项目基于已有的Monte Carlo电子与金属原子散射模型，依照化学吸附键力的不同构建不同形态的复杂表面势垒，采用第一性原理方法计算电子跨越表面势垒的概率。基于Polanyi位势理论特殊形式建立物理吸附模型，全程采用Monte Carlo方法实现电子与表面吸附物散射过程的精确数值模拟。开展超高真空下表面吸附的金属二次电子发射特性实验研究，验证相关计算模型。通过研究将阐明空间电子辐照环境下，金属二次电子产额与与表面势垒形态、高度、厚度、吸附量、吸附厚度、密度等参数之间的定量关系，获得金属表面微放电敏感区域。本项目对于全面了解吸附表面状态下空间电子与金属相互作用导致的二次电子发射效应的微观机理、提高我国航天器故障机理的研究水平，具有重要的科学意义和应用价值。

表面吸附是制约航天器微放电阈值提高的重要因素，但目前对于表面吸附层对电子辐照金属二次电子发射动态过程及微观机理的影响仍缺乏了解。本项目基于已有的Monte Carlo电子与金属原子散射模型，采用第一性原理方法构建电子跨越表面势垒的模型。基于Polanyi位势理论特殊形式建立物理吸附模型，全程采用Monte Carlo方法实现电子与表面吸附物散射过程的精确数值模拟。开展超高真空下表面吸附的金属二次电子发射特性实验研究，验证相关计算模型。通过研究阐明空间电子辐照环境下，金属二次电子产额与与表面势垒高度、吸附量、吸附厚度、密度等参数之间的定量关系，获得金属表面微放电敏感区域。本项目对于全面了解吸附表面状态下空间电子与金属相互作用导致的二次电子发射效应的微观机理、提高我国航天器故障机理的研究水平，具有重要的科学意义和应用价值。