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作为一个典型的高功率微波振荡器, 过模返波管(backward wave oscillator, BWO)的束波互作用过程复杂, 束流负载效应影响明显, 但是作为振荡器本身, 其本质就是一个正反馈电路, 电子从阴极发射后, 穿过谐振反射腔和慢波结构(slow-wave structure, SWS), 在SWS区电子动能转化为微波能, 其中的一部分微波反馈到谐振反射腔, 实现对电子束的调制, 其他微波通过后面输出端口向外辐射. 本文根据这种正反馈机制, 建立器件工作模式等效电路和束波互作用的自洽过程, 从理论上给出正反馈机制对器件模式控制、起振电流等参数的影响, 并模拟研究了这种反馈机制对模式控制的影响, 由此设计了一个能够在(1 MV, 20 kA)电子束条件下克服模式竞争的过模BWO, 其微波输出功率为7.9 GW, 频率为8.68 GHz, 相应的效率为39.5%.Internal field emission breakdown in the electro-dynamic structures of high-power microwave devices can seriously limit the devices’ output power and pulse duration. So an over-sized backward wave oscillator (BWO) is developed to increase the diameter of the electro-dynamic structure beyond the cut-off radius, and reduce these internal fields to levels, which are below critical breakdown levels. As a typical high power microwave (HPM) device, the oversized BWO is widely used and investigated. But some interaction phenomena between the beam and the microwave field in the device are not clearly understood because the beam-loaded effect is so obvious. And the physical process for the interaction is also considered to be complicated. Here as an oscillator, the feedback process is very important in the microwave device, which includes the oversized BWO. So the interaction process between the beam and the oversized BWO is explored from the feed back process instead of the field in the device. Then the physical mechanism for the feedback process in the oversized BWO is explored both in theoretical investigation and in particle-in-cell simulation. And the equivalent circuit is established for such a purpose. The mode control mechanism is explored based on the equivalent circuit. Finally an over-sized backward wave oscillator with rectangular profile corrugations is designed to produce TM01 high power microwave radiation without mode-competition. An RF power of 7.9 GW at a frequency of 8.68 GHz is obtained in the particle in cell simulation driven by the beam with a beam voltage of 1 MW and a current of 20 kA, and the corresponding efficiency is 39.5%.
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Keywords:
- high power microwave /
- back-ward wave oscillator /
- mode-control /
- particle in cell
[1] Li Z H 2008 Appl. Phys. Lett. 92 054102Google Scholar
[2] Korovin S D, Mesyats G A, Pegel I V, Polevin S D, Tarakanov V P 2004 IEEE Trans. Plasma Sci. 28 2691
[3] Li Z H, Zhou Z G, Qiu R 2014 Phys. Plasmas 21 103105Google Scholar
[4] Xiao R Z, Zhang X W, Zhang L G 2012 Phys. Plasmas 19 073106Google Scholar
[5] 杨振萍, 李正红 2008 物理学报 57 2627Google Scholar
Yang Z P, Li Z H 2008 Acta Phys. Sin. 57 2627Google Scholar
[6] 李正红, 常安碧, 鞠炳全 2007 物理学报 56 2603Google Scholar
Li Z H, Chang A B, Ju B Q 2007 Acta Phys. Sin. 56 2603Google Scholar
[7] Li, Z H 2005 Proceedings of IEEE International Symposium on Microwave, Antenna, Propagation and EMC Technologies for Wireless Communication Beijing 1 519
[8] Li Z H 2010 Phys. Plasmas 17 023113
[9] 李正红, 孟凡宝, 常安碧 2005 物理学报 54 3578Google Scholar
Li Z H, Meng F B, Chang A B, 2005 Acta Phys. Sin. 54 3578Google Scholar
[10] 李正红, 孟凡宝, 胡克松 2004 物理学报 53 3627Google Scholar
Li Z H, Meng F B, Hu S K 2004 Acta Phys. Sin. 53 3627Google Scholar
[11] Zhang J, Jin Z X, Yan J H, Shu T, Zhang J D 2015 IEEE Trans. Plasma Sci. 43 528Google Scholar
[12] Jin Z X, Zhang J H, Zhong H H, Qian B L, Shu T 2011 Rev. Sci. Instrum. 82 084704Google Scholar
[13] Wu Y, Xie H Q, Li Z H, Zhang Y J, Ma Q S 2013 Phys. Plasmas 20 113102Google Scholar
[14] Xiao R Z, Chan C H, Zhang X W, Shun J 2009 J. Appl. Phys. 105 053306Google Scholar
[15] Xiao R Z, Chan C H, Zhang X W 2013 Appl. Phys. Lett. 102 133504Google Scholar
[16] Wu Y 2017 Phys. Plasmas 24 073105Google Scholar
[17] Song W, Chen C H, Sun J, Zhang X W, Shao H 2012 Phys. Plasmas 19 1031111
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表 1 器件结构参数
Table 1. Parameters of the device.
Cavity radius of the resonate reflector Cavity width of the resonate reflector Drifting distance Outer radius of SWS Inner radius of SWS SWS’s period 3.2 cm 1.6 cm 5.4 cm 2.8 cm 2.5 cm 1.6 cm 表 2 有初始调制(10.73 GHz)电子束在不同流强下的模拟微波输出功率
Table 2. Output RF power and frequency when the device is driven by the electron beam with the initial modulation at the frequency of 10.73 GHz.
Beam current /kA 10 12 14 16 18 20 22 With initial modulation RF power/GW 0.68 3.10 4.10 4.50 6.70 7.90 7.80 RF frequency/GHz 10.73 10.73 10.73 10.73 8.63 8.59 8.58 No initial modulation RF power /GW 0 0 5.20 6.50 7.70 7.90 7.80 RF frequency/GHz 8.69 8.66 8.63 8.59 8.58 -
[1] Li Z H 2008 Appl. Phys. Lett. 92 054102Google Scholar
[2] Korovin S D, Mesyats G A, Pegel I V, Polevin S D, Tarakanov V P 2004 IEEE Trans. Plasma Sci. 28 2691
[3] Li Z H, Zhou Z G, Qiu R 2014 Phys. Plasmas 21 103105Google Scholar
[4] Xiao R Z, Zhang X W, Zhang L G 2012 Phys. Plasmas 19 073106Google Scholar
[5] 杨振萍, 李正红 2008 物理学报 57 2627Google Scholar
Yang Z P, Li Z H 2008 Acta Phys. Sin. 57 2627Google Scholar
[6] 李正红, 常安碧, 鞠炳全 2007 物理学报 56 2603Google Scholar
Li Z H, Chang A B, Ju B Q 2007 Acta Phys. Sin. 56 2603Google Scholar
[7] Li, Z H 2005 Proceedings of IEEE International Symposium on Microwave, Antenna, Propagation and EMC Technologies for Wireless Communication Beijing 1 519
[8] Li Z H 2010 Phys. Plasmas 17 023113
[9] 李正红, 孟凡宝, 常安碧 2005 物理学报 54 3578Google Scholar
Li Z H, Meng F B, Chang A B, 2005 Acta Phys. Sin. 54 3578Google Scholar
[10] 李正红, 孟凡宝, 胡克松 2004 物理学报 53 3627Google Scholar
Li Z H, Meng F B, Hu S K 2004 Acta Phys. Sin. 53 3627Google Scholar
[11] Zhang J, Jin Z X, Yan J H, Shu T, Zhang J D 2015 IEEE Trans. Plasma Sci. 43 528Google Scholar
[12] Jin Z X, Zhang J H, Zhong H H, Qian B L, Shu T 2011 Rev. Sci. Instrum. 82 084704Google Scholar
[13] Wu Y, Xie H Q, Li Z H, Zhang Y J, Ma Q S 2013 Phys. Plasmas 20 113102Google Scholar
[14] Xiao R Z, Chan C H, Zhang X W, Shun J 2009 J. Appl. Phys. 105 053306Google Scholar
[15] Xiao R Z, Chan C H, Zhang X W 2013 Appl. Phys. Lett. 102 133504Google Scholar
[16] Wu Y 2017 Phys. Plasmas 24 073105Google Scholar
[17] Song W, Chen C H, Sun J, Zhang X W, Shao H 2012 Phys. Plasmas 19 1031111
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