| 介质材料二次电子发射特性对微波击穿的影响 |
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| 引用本文： | 翁明,谢少毅,殷明,曹猛. 介质材料二次电子发射特性对微波击穿的影响[J]. 物理学报, 2020, 0(8): 210-216 |
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| 作者姓名： | 翁明 谢少毅 殷明 曹猛 |
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| 作者单位： | 西安交通大学电子与信息学部;西北核技术研究院 |
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| 基金项目： | 国家自然科学基金(批准号:61971342,U1537210)资助的课题. |
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| 摘 要： | 以介质填充的平行板放电结构为例,本文主要研究了介质填充后微波低气压放电和微放电的物理过程.为了探究介质材料特性对微波低气压放电和微放电阈值的影响,本文采用自主研发的二次电子发射特性测量装置,测量了7种常见介质材料的二次电子发射系数和二次电子能谱.依据二次电子发射过程中介质表面正带电的稳定条件,计算了介质材料稳态表面电位与二次电子发射系数以及能谱参数的关系.在放电结构中引入与表面电位相应的等效直流电场后,依据电子扩散模型和微放电中电子谐振条件,分别探讨了介质表面稳态表面电位的大小对微波低气压放电和微放电阈值的影响.结果表明,介质材料的二次电子发射系数以及能谱参数越大,介质材料的稳态表面电位也越大,对应的微波低气压放电和微放电阈值也越大.所得结论对于填充介质的选择有一定的理论指导价值.
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| 关 键 词： | 二次电子发射系数 二次电子能谱 表面电位 微波击穿 |
Influence of secondary electron emission characteristic of dielectric materials on microwave breakdown |
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| Weng Ming,Xie Shao-Yi,Yin Ming,Cao Meng. Influence of secondary electron emission characteristic of dielectric materials on microwave breakdown[J]. Acta Physica Sinica, 2020, 0(8): 210-216 |
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| Authors: | Weng Ming Xie Shao-Yi Yin Ming Cao Meng |
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| Affiliation: | (Key laboratory of Physical Electronics and Devices,Ministry of Education,School of Electronic and Informtion Engineering,Xi’an Jiaotong University,Xi’an 710049,China;Northwest Institute of Nuclear Technology,Xi’an 710613,China) |
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| Abstract: | For a microwave device filled with dielectrics,the secondary electron(SE)emission has a very important influence on the mechanism of microwave breakdown including low pressure discharge and multipactor.In this work,the SE yields(SEYs)and the SE energy spectra of seven kinds of dielectric materials are first measured and then used to examine their effects.In the positive charging process under electron irradiation,the surface potential of the dielectric layer trends to be steady with the SEY being one.Based on the measurement data,the steady surface potential is calculated under the charging stability condition.The steady surface potential is bigger for a bigger SEY.For a given SEY,the steady surface potential is found to be proportional to the peak energy Epeak of the SE energy spectrum.Furthermore,the effect of steady surface potential on low pressure discharge and multipactor are respectively studied for a parallel plate system filled with a dielectric layer.A static electric field related to the positive charging is introduced.The electron diffusion model in low pressure discharge process is modified by considering the static electric field.The electrons drift in a fixed direction under the action of static electric field,and the electron diffusion length decreases.Consequently,the effective electrons for low discharge decreases and the threshold microwave power increases.Therefore,a dielectric material with higher SEY and bigger Epeak is helpful in suspending the inhibition of low pressure discharge.Furthermore,the effect of steady electric field on multipactor is also explored.Two effects related to dielectric material and metal are analyzed in detail.The SE emission from dielectric material is held back by the steady electric field and some low energy electrons return back to the dielectric materials.The effective SEY thus decreases.On the other hand,the electric field reduces the landing electron energy on the metal,and the corresponding SEY also decreases.The electron oscillation condition with considering both microwave field and stead electric field is derived and the threshold values for microwave power of multipactor are calculated.The susceptibility curves corresponding to different materials are plotted.Our result may be used to choose the filling dielectric materials for a microwave device. |
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| Keywords: | secondary electron yield secondary electron energy spectrum surface potential microwave breakdown |
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