| 频率色散表面阻抗对真空电子太赫兹源的影响 |
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| 引用本文： | 任泽平,陈再高,陈剑楠,乔海亮.频率色散表面阻抗对真空电子太赫兹源的影响[J].物理学报,2020(4):70-78. |
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| 作者姓名： | 任泽平 陈再高 陈剑楠 乔海亮 |
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| 作者单位： | 西北核技术研究院 |
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| 基金项目： | 国家自然科学基金(61231003)资助课题~~ |
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| 摘 要： | 为了研究欧姆损耗对高频真空电子器件工作特性的影响,首先推导频率色散表面阻抗边界在三维共形粒子模拟软件UNIPIC-3D中的实现原理,并通过对有耗边界矩形谐振腔和圆波导进行模拟验证了该阻抗边界算法的正确性.采用有耗共形UNIPIC-3D模拟相对论太赫兹表面波振荡器和低电压平板格栅返波振荡器.模拟结果表明,对于表面波振荡器和平板BWO这种电磁场集中在金属慢波结构附近的太赫兹真空电子器件,欧姆损耗会对器件的运行带来极大影响,对于采用铜材料的器件,输出功率会下降一半左右,器件起振时间出现延迟,但器件工作频率几乎不变.为了提高相对论太赫兹表面波振荡器的效率,在二极管和慢波结构之间增加了反射腔,模拟结果表明,在考虑器件表面损耗的条件下,器件的工作频率保持不变,输出功率由41 MW提高到60 MW.
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| 关 键 词： | 表面阻抗边界 欧姆损耗 粒子模拟 太赫兹器件 表面波振荡器 返波管 |
Effects of frequency-dependent surface impedance on the vacuum electronic terahertz sources |
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| Ren Ze-Ping,Chen Zai-Gao,Chen Jian-Nan,Qiao Hai-Liang.Effects of frequency-dependent surface impedance on the vacuum electronic terahertz sources[J].Acta Physica Sinica,2020(4):70-78. |
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| Authors: | Ren Ze-Ping Chen Zai-Gao Chen Jian-Nan Qiao Hai-Liang |
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| Affiliation: | (Northwest Institute of Nuclear Technology,Xi’an 710024,China) |
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| Abstract: | When the working frequency of vacuum electronic device reaches the terahertz frequency,the ohmic loss has a significant impact on the vacuum electronic device.To study the effect of the ohmic loss on the working characteristic of the vacuum electronic terahertz devices,this paper implements the frequency-dependent surface impedance boundary condition(SIBC)in the 3 dimensional particle in cell code UNIPIC-3D.Conformal mesh is adopted in the code to overcome the staircase error in traditional particle in cell method.By using the surface impedance boundary,we eliminate the need to study the field inside the lossy dielectric objects which require extremely small grid cells for numerical stability.In comparison with constant parameter SIBC,the dispersive SIBC is applicable over a very large frequency bandwidth and over a large range of conductivities.The correctness of the implementation is verified by simulating the lossy resonant cavity and circular waveguide,the simulated power loss is comparable with the theoretical predication.High power vacuum electronic devices of terahertz regime are attracting extensive interests due to their potential applications in science and technologies.The impulse-wave relativistic surface wave oscillator(SWO)and low-voltage continuous-wave planar grating backward wave oscillator(BWO)both made of copper are numerically studied by using UNIPIC-3D and dispersive surface impedance boundary condition.Numerical results show that the strongest field is very close to the slow wave structure where the beam-wave interaction occurs and that terahertz wave generates both in these two devices.The distributed wall loss has a considerable effect on the devices:the output power has a significant decrease and the startup time becomes longer,but the working frequencies of the two devices keep unchanged.To improve the efficiency of relativistic SWO,a resonant reflector is proposed between the diode and the slow wave structure.Numerical results show that the working frequency of the device with a resonant reflector keeps unchanged as the original one,but the output power increases to 60 MW from 41 MW of the original one when the ohmic loss is considered. |
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| Keywords: | surface impedance boundary Ohmic loss particle in cell terahertz device surface wave oscillator BWO |
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