【作者】 曹亦兵；

【导师】 张建德； 贺军涛；

【作者基本信息】 国防科学技术大学 ， 物理电子学， 2008， 硕士

【摘要】 传统轴向渡越器件大多工作在高阻抗状态,关于低阻抗渡越器件的研究主要集中于径向渡越时间振荡器,并且几乎所有的这些渡越器件都存在栅网结构。高阻抗器件不利于与提供高电功率的低阻抗脉冲功率驱动源相配合,而栅网结构则不利于实现长脉冲和重复频率运行。目前,关于低阻无箔结构的渡越器件国内外尚未见报道,实验研究更是空白。基于此,本文提出了一种新型结构的低阻无箔渡越辐射振荡器,并且从理论和数值分析、粒子模拟及工程设计等方面对新型渡越器件进行了系统研究。论文首先运用小信号理论研究了电子注与任意驻波场的相互作用,得到了表征电子注能量得失的电子注负载电导表达式,得到了电子注加载引起的本征场频率漂移和射频场时间增长率表达式;同时用数值计算的方法研究了L波段新型低阻无箔渡越辐射振荡器的高频特性,得到了同轴漂移段长度改变对腔体本征模场的影响规律;借助小信号理论和数值计算分析了L波段新型低阻无箔渡越辐射振荡器的束波相互作用规律,得到了新型器件的电压工作范围,得到了电子注加载对腔体本征场频率的影响。其次,重点对L波段新型低阻无箔渡越辐射振荡器进行了模拟研究。在输入电子注压600kV、束流36kA、约束磁场0.45T的情况下,在L波段得到了超过5GW的微波功率输出,主频为1.6GHz,束波转换效率为23.1%,功率饱和时间在15ns左右,工作模式为类p模。对S波段、C波段和X波段的低阻无箔渡越辐射振荡器也进行了初步粒子模拟。S波段典型的粒子模拟结果为:在输入束压和束流分别为550kV和27.6kA、约束磁场为0.8T的情况下,在3.175GHz处得到了大约4.0GW的微波功率输出,束波转换效率为26.4%,功率饱和时间约10ns。在几乎相同的输入电压下,C波段和X波段均获得了超过2.0GW的微波功率输出,束波效率在20%左右。最后,对L波段新型低阻无箔渡越辐射振荡器进行了相关工程方面的设计。重点设计了新型低阻无箔渡越辐射振荡器的励磁系统,计算了螺线管产生满足要求的约束磁场所需的电容器数目。螺线管在22.0ms时达到最大电流600A,40ms的时间内线圈升温约0.261K,匝间间隙0.5mm时产生的匝间电动力约为144N。利用工程计算软件设计了支撑杆和模式转换器。选取每排支撑杆数目为5的相距λ/4的两排支撑杆结构,在频率1.5GHz~1.68GHz的范围内,微波能量传输系数超过99%。模式转换器把同轴TEM模转化为TM01模向外围空间辐射,在给定的结构尺寸下,最大增益方向角为27±。更多还原

【Abstract】 The conventional HPM source based on the axial transit-time effect usually has a high diode impedance, and only the radial transit-time oscillator has been studied as a main low-impedance HPM source. Moreover, most of these HPM sources have a foil structure. The high-impedance devices can’t matched well with the low-impedance pulsed power sources providing high electric power. And that the foil structure is disadvantageous for long pulse and repetitive operation. Up to now, the low-impedance oscillator without foils based on transit-time effect has not been reported over the world, and there has been no experimental research in this field. In this paper, a novel L-band low-impedance transit radiation oscillator (LITRO) was designed without foils. By use of theoretical and numerical analysis, particle simulation, and related engineering design, the LITRO has been investigated systematically and a series of useful conclusions and laws are presented.Firstly, on the basis of the small signal theory, the transit-time effect of electron beam passing through the gap with random standing wave electric field is studied, and the analytic formula of electron load conductance implying the beam-wave energy interchange is derived. Under such a condition,mathematical expressions of the frequency offset caused by the electron beam and the RF field increasing rate along with the time are discussed. Meanwhile, the high frequency features of the novel L-band LITRO have been investigated numerically. The influences of a span change of the drift-tube on the eigenmode and on the corresponding frequency have been obtained. Combined the numerical analysis and the small signal theory, the interaction between the electron beam and the eigenmode in the LITRO is investigated. Eventually, the voltage work area of LITRO is gotten and the eigenfrequency change caused by electron beam is considered.Secondly, the LITRO has been simulated by a 2.5D particle-in-cell code. With the voltage 600kV, the current 36kA and the magnetic field 0.45T in the simulation, the output power is over 5GW at the main frequency 1.60GHz with 15ns duration. The beam-to-microwave power conversion efficiency is 23.1%, and the working mode of the LITRO is p-like mode. Moreover, the oscillators on S-band, C-band and X-band have also been studied in our simulation and some primary results have been obtained. The typical S-band output power is about 4GW at the main frequency 3.175GHz with the voltage 550kV, the current 27.6kA and the magnetic field 0.8T, respectively. The beam-to-microwave power conversion efficiency is 26.4%. With the same input voltage, both the output power of C-band and that of X-band are also over 2.0GW with the efficiency about 20%.Finally, a related engineering design is proposed in our paper. The magnetic system of LITRO is designed chiefly and the number of the capacitors is calculated. By employing such a solenoid, the peak current reaches 600A at the time 22.0ms. The rising temperature of the coils is about 0.261K in 40ms. The force between any two adjacent circles is less than 144N with a distance of 0.5mm. Furthermore, some struts and a mode converter are also optimized by a simulation code. In the case of two rows struts with the distance ofλ/4 and five struts per row used, the energy transmission coefficient exceeds 99% at frequency ranged from 1.5GHz to 1.68GHz. By using the mode converter from TEM to TM01, the maximum gain is in the direction of 27±off the principal axis with the given structure parameters.更多还原