X波段相对论返波管振荡器研究

【作者】 马乔生；

【导师】 周传明；

【作者基本信息】 中国工程物理研究院 ， 无线电物理， 2008， 博士

【摘要】 返波管（Backward Wave Oscillator,BWO）是输出微波功率最高的微波器件之一,相对论返波管振荡器需要一个体积庞大、高耗能的引导磁场系统。本文主要目的就是解决磁场问题,对小径向尺寸的低磁场返波管进行了研究。本论文共分为3部分:第一部分包括第二章和第三章,它主要对返波管振荡器进行了理论研究,推导了返波管产生的微波的频率与电子束参数、慢波结构参数之间的解析关系式,对正弦慢波结构给出了较为准确的结论,为返波管优化设计提供了理论指导;同时,从线性化的Vlasov方程出发,首次推导了返波管产生的微波功率与引导磁场之间的关系,该结论与以前的实验结果基本一致;第二部分包括第四章和第五章,它首先通过数值模拟对相对论返波管振荡进行了设计,在返波管为七腔结构（腔的平均半径为1.527cm,腔的深度0.375cm,轴向周期1.7cm）、电子束为环形电子束（电子束束环平均半径为0.95cm,束环厚度为1mm）、电子束束压为900kV、电子束束流为6.7kA、引导磁场为3.2T时,得到输出微波功率约为1.2GW,输出微波的频率为9.4GHz,束波转换效率约为20%;然后对相对论返波管振荡进行了实验研究,二极管电压约为790kV、电流约为6.7kA并以100Hz重复频率运行时得到了微波输出功率为1.4GW、微波频率为9.4GHz、微波脉宽为30ns、束波转换效率为26%且100次波形之间分散性较小的实验结果;第三部分包括第六章和第七章,首先对低磁场返波管振荡器的数值模拟,当电子束束压为760kV、束流为7.2kA、引导磁场强度为0.73T时,输出微波功率约为1.2GW、微波频率约为9.3GHz,微波模式为TM₀₁,束波转换效率约为25%;然后对低磁场返波管振荡器进行了实验研究,当引导磁场强度为0.68T、电子束束压为740kV、总电流为12kA、束流为7kA时,低磁场返波管振荡得到频率为9.1GHz、功率为1.15GW、模式为TM₀₁模、脉冲半高宽越22ns的微波输出,器件的束波转换效率约为22%,该结果与国内外低磁场器件的水平相当,但是本器件有一个明显的优势,那就是器件的径向尺寸是同波段的低磁场器件中最小的,因此也是最有利于实现永磁包装的低磁场器件。更多还原

【Abstract】 Backward wave oscillator（BWO） is one of the microwave devices having the highest output power,but a voluminous guiding magnetic field system,which is also an undesirable energy-consumer is needed.The BWO with small radial dimension and low magnetic field is studied here.The dissertation mainly involves three parts:In part one,consisting of chapter 2 and chapter 3,the BWO is theoretically studied.The analytical formula,which uncovers the relationship between microwave frequency and parameters of electron beam and slow wave structure（SWS）,is derived.The formula is very exact for sinusoidal SWS.Simultaneity,based on the linear Vlasov equation,the relationship between output power and guiding magnetic field,which accords with the experimental results,is gained.In part two,consisting of chapter 4 and chapter 5,a relativistic BWO is investigated. Firstly,the BWO with 7 periods SWS is designed by particle in cell（PIC） simulation.When the average radius and thickness of annular electron beam is 0.95cm and 1mm,the voltage and current of electron beam is 900kV and 6.7kA,the strength of guiding magnetic field is 3.2T, the performance of 1.2GW microwave output power at 9.4GHz microwave frequency and 22%conversion efficiency are obtained.Secondly,the relativistic BWO is experimentally investigated.Under the condition that the electron energy is 790keV,the beam current is 7.6kA and the guiding magnetic field is at 2.3T,the performance of 1.4GW microwave output power at 9.4GHz microwave frequency with 30ns pulse width and 26%conversion efficiency are obtained and consistency of microwave waveforms is very good.In part three,consisting of chapter 6 and chapter 7,a relativistic BWO with low magnetic field is investigated.Firstly,the BWO is simulated by the particle in cell（PIC） code KARAT. When the voltage and current of electron beam is respectively 760kV and 7.2kA,the strength of guiding magnetic field is 0.73T,the performance of 1.2GW microwave output power at 9.3GHz microwave frequency and 25%conversion efficiency are obtained and the mode of the microwave is TM₀₁.Secondly,the relativistic BWO with low magnetic field is experimentally investigated.Under the condition that the electron energy is 740keV,the beam current is 7kA（the total current,which includes the beam current and the loss current,is 12KA） and the guiding magnetic field is at 0.68T,the performance of 1.15GW microwave output power at 9.1GHz microwave frequency with 22ns pulse width and 22%conversion efficiency are obtained and the mode of the microwave is TM₀₁.The BWO is on the same level with other microwave devices with low magnetic field in the world,but it has the smallest radial dimension.So it is possible to develop practical HPM source guided by a permanent magnetic field.更多还原