二次电子发射模型的精度对精确预测空间大功率微波部件微放电阈值有很大影响。针对现有二次电子发射唯象模型的不足,采用分段函数的思想建立了一种计算金属材料二次电子发射系数(secondary electron yield,SEY)的复合半经验模型。该模型...二次电子发射模型的精度对精确预测空间大功率微波部件微放电阈值有很大影响。针对现有二次电子发射唯象模型的不足,采用分段函数的思想建立了一种计算金属材料二次电子发射系数(secondary electron yield,SEY)的复合半经验模型。该模型以Vaughan模型计算入射能量Ep<Epm(二次电子发射系数最大值所对应的入射电子能量)时材料的二次电子发射系数,以文中建立的半经验模型计算入射能量Ep≥Epm时材料的二次电子发射系数,并利用钼和银两种材料二次电子发射系数的测试结果对复合半经验模型进行了验证。模拟结果表明,复合半经验模型能够对溅射清洗前后及不同入射极角条件下的SEY进行精确表征,相对误差的平均值和均方差明显低于Vaughan模型和半经验模型,且在不同入射极角条件下该模型具有较好的稳定性,在很大程度上提高了二次电子发射模型与实验数据拟合的准确性。该模型有望应用于空间大功率微波部件的微放电功率阈值的模拟。展开更多
The surface adsorption of gas molecules is a key factor limiting the secondary electron yield(SEY)of a material in many areas of applied physics.The influence of O_(2)adsorption on the SEY of metallic Ag is investigat...The surface adsorption of gas molecules is a key factor limiting the secondary electron yield(SEY)of a material in many areas of applied physics.The influence of O_(2)adsorption on the SEY of metallic Ag is investigated in this work.To account for the particle distribution,we propose a BET theory based on multilayer O_(2)physisorption model.Furthermore,based on the phenomenological model of secondary electron(SE)emission and by taking into account the different scattering processes between electrons and particles in the adsorbed layer,we develop a numerical model of SEY in the adsorbed state using Monte Carlo simulations.The relationships among O_(2)adsorption,adsorption layer thickness,and SEY variation characteristics are then examined through a series of experiments.After 12-h exposure to O_(2),the clean samples increases12%-19%of the maximum value of SEY and 2.3 nm in thickness of the adsorbed layer.Experimental results are also compared with the results from the MC model to determine whether the model is accurate.展开更多
钼具有高熔点、低的热膨胀系数和极佳的稳定性,在等离子体推进和电真空器件领域具有广阔的应用前景,其二次电子发射特性也逐渐引起了研究者们的关注。本研究首先对钼的二次电子发射系数(secondary electron yield, SEY)和二次电子能谱(s...钼具有高熔点、低的热膨胀系数和极佳的稳定性,在等离子体推进和电真空器件领域具有广阔的应用前景,其二次电子发射特性也逐渐引起了研究者们的关注。本研究首先对钼的二次电子发射系数(secondary electron yield, SEY)和二次电子能谱(secondaryelectronspectrum, SES)展开实验研究,其次利用相关唯象模型对测试数据进行分析;最后建立钼SEY的蒙特卡罗模型,用于分析功函数对SEY的影响规律。结果表明:钼SEY的最大值为1.77,相比镀银铝合金明显降低。当入射电子能量改变时,SES中真二次电子峰的最可几能量基本不变,而弹性背散射电子峰的位置和强度均随之改变。在各类二次电子中,真二次电子受功函数的影响最大。展开更多
文摘二次电子发射模型的精度对精确预测空间大功率微波部件微放电阈值有很大影响。针对现有二次电子发射唯象模型的不足,采用分段函数的思想建立了一种计算金属材料二次电子发射系数(secondary electron yield,SEY)的复合半经验模型。该模型以Vaughan模型计算入射能量Ep<Epm(二次电子发射系数最大值所对应的入射电子能量)时材料的二次电子发射系数,以文中建立的半经验模型计算入射能量Ep≥Epm时材料的二次电子发射系数,并利用钼和银两种材料二次电子发射系数的测试结果对复合半经验模型进行了验证。模拟结果表明,复合半经验模型能够对溅射清洗前后及不同入射极角条件下的SEY进行精确表征,相对误差的平均值和均方差明显低于Vaughan模型和半经验模型,且在不同入射极角条件下该模型具有较好的稳定性,在很大程度上提高了二次电子发射模型与实验数据拟合的准确性。该模型有望应用于空间大功率微波部件的微放电功率阈值的模拟。
基金Project supported by the Fund from the National Key Laboratory of Science and Technology on Space Mircrowave,China(Grant No.6142411112205)the National Natural Science Foundation of China(Grant No.62001376)。
文摘The surface adsorption of gas molecules is a key factor limiting the secondary electron yield(SEY)of a material in many areas of applied physics.The influence of O_(2)adsorption on the SEY of metallic Ag is investigated in this work.To account for the particle distribution,we propose a BET theory based on multilayer O_(2)physisorption model.Furthermore,based on the phenomenological model of secondary electron(SE)emission and by taking into account the different scattering processes between electrons and particles in the adsorbed layer,we develop a numerical model of SEY in the adsorbed state using Monte Carlo simulations.The relationships among O_(2)adsorption,adsorption layer thickness,and SEY variation characteristics are then examined through a series of experiments.After 12-h exposure to O_(2),the clean samples increases12%-19%of the maximum value of SEY and 2.3 nm in thickness of the adsorbed layer.Experimental results are also compared with the results from the MC model to determine whether the model is accurate.
文摘钼具有高熔点、低的热膨胀系数和极佳的稳定性,在等离子体推进和电真空器件领域具有广阔的应用前景,其二次电子发射特性也逐渐引起了研究者们的关注。本研究首先对钼的二次电子发射系数(secondary electron yield, SEY)和二次电子能谱(secondaryelectronspectrum, SES)展开实验研究,其次利用相关唯象模型对测试数据进行分析;最后建立钼SEY的蒙特卡罗模型,用于分析功函数对SEY的影响规律。结果表明:钼SEY的最大值为1.77,相比镀银铝合金明显降低。当入射电子能量改变时,SES中真二次电子峰的最可几能量基本不变,而弹性背散射电子峰的位置和强度均随之改变。在各类二次电子中,真二次电子受功函数的影响最大。
