【作者】 王新；

【导师】 段兆云；

【作者基本信息】 电子科技大学 ， 电子科学与技术， 2021， 博士

【摘要】 扩展互作用器件是利用扩展互作用谐振腔中的驻波场与电子注进行互作用而发生能量交换的一种线性注真空电子器件,包括扩展互作用振荡器和扩展互作用速调管。由于速调管具有高功率、高效率和良好的稳定性等特点,被广泛应用于医疗辐照、射电天文、工业加热和大科学装置等领域。然而,随着科技日新月异的发展,特别是在大科学装置的应用当中,包括加速器、对撞机、可控热核聚变反应装置等对器件的小型化、大功率、高效率和稳定性等提出了更高的要求。鉴于此,本学位论文创造性地将超材料与扩展互作用技术相结合,开展了超材料扩展互作用振荡器（MEIO）和超材料扩展互作用速调管（MEIK）的理论、仿真和实验研究。在研究超材料的电磁特性和超材料扩展互作用谐振腔（MEIRC）的电磁特性的基础之上,利用MEIRC作为高频结构探索MEIO和MEIK在实现小型化、大功率和高效率等方面的潜在优势。论文的主要研究内容和创新点如下:（1）开展了超材料电磁特性相关的理论和仿真研究,研究了超材料的谐振特性、负有效电磁参数以及超材料慢波结构的色散和传输特性之间的对应关系。从理论上推导了不同导波系统中有效电磁参数的表达式,并在此基础上提出了一种小型化的全金属超材料单元,通过本征模和时域仿真研究了超材料慢波结构的高频特性和传输特性。与此同时,定义了一种表征超材料小型化程度的小型化系数,研究了横向小型化系数（垂直电磁波传播方向的小型化系数）和纵向小型化系数（沿着电磁波传播方向的小型化系数）对色散特性的影响。研究表明:纵向小型化系数对超材料慢波结构的色散起着决定性的作用,而横向小型化系数则主要影响色散通带的偏移。（2）开展了超材料慢波结构的理论、仿真和实验研究。采用等效电路理论研究了圆波导加载互补电开口环谐振器（Ce SRR）阵列构成的超材料慢波结构的高频特性,通过色散方程和耦合阻抗方程分析了Ce SRR单元和腔体的结构参数对高频特性的影响。在此基础上,开展了超材料慢波结构的传输实验研究。通过仿真和实验得到的传输特性证实了由超材料负折射率导致的传输通带,即工作在圆波导TM₀₁模式截止频率以下的传输通带。研究了超材料关键结构参数对超材料慢波结构高频特性和传输特性的影响,特别是分析了影响超材料慢波结构和MEIRC电磁特性的主要因素,为进一步研究MEIO和MEIK提供了理论和实验依据。（3）提出了小型化和高电子效率MEIO的设计方案,分别研究了低电压小型化和兆瓦级高电子效率的MEIO。首先,研究了多间隙MEIRC的模式分布,并基于归一化电子负载电导和功率交换函数的方法,提出了一种工作在S波段的小型化低电压的MEIO,其横向尺寸和纵向尺寸分别为0.2λ和0.72λ（其中λ为工作频率所对应的自由空间波长）。与此同时,研究了不同间隙个数对MEIO的输出功率的影响,提出了一种兆瓦级的小型化MEIO,并分析了在提高电子效率的同时抑制电子回流的方法,最终通过仿真预测了一个工作在2.866GHz、输出功率达到4.9MW、电子效率为46%的MEIO,其横向尺寸和纵向尺寸分别为0.35λ和1.71λ。（4）提出了一种具有小型化和高电子效率的MEIK,并开展仿真和冷测实验研究。通过计算和仿真研究了MEIRC的电磁特性,分析了MEIRC在结构尺寸和电磁特性方面的潜在优势。在此基础上开展了双腔MEIK的冷测实验研究,通过实验证实了其小型化特性。进一步开展了三腔MEIK的模拟研究,在S波段获得56k W的饱和输出功率,62%的电子效率和47d B的饱和增益,其腔体直径约为0.27λ。最后分析了MEIK的稳定性,聚焦磁场以及由结构小型化可能引起的高频击穿风险。（5）开展了应用于加速器系统的大功率MEIK的研究,针对不同功率量级的应用需求提出了相应的技术方案,并开展相关的实验研究。模拟研究结果表明:中心工作频率为650MHz的三腔MEIK的腔体直径约为0.33λ,约为常规速调管的2/3;在互作用长度小于1.5m的情况下实现了饱和输出功率651k W、电子效率52.8%以及增益35d B的性能。与此同时,研究了基于超材料的兆瓦级脉冲功率速调管,其腔体的横向尺寸为0.34λ。在注电压125k V、注电流80A、聚焦磁场0.2T、输入功率18W的条件下,在中心频率为2.856GHz处得到饱和输出功率为6.2MW、饱和增益为55d B、对应的电子效率超过60%。最后,开展了超材料大功率速调管的热测实验研究,在电子注电压和电流分别为120k V和80A的条件下,在2.852GHz-2.858GHz的频率范围内得到输出功率大于4MW。其中最大输出功率为5.51MW,电子效率为57.4%,饱和增益为54.9d B,对应的工作频率为2.8523GHz。更多还原

【Abstract】 Extended interaction device is one of the linear beam vacuum electron devices by energy exchange between standing wave in extended interaction resonant cavity and electron beam,which includes an extended interaction oscillator and an extended interaction klystron.They are widely applicated in the fields of medical irradiation,radio astronomy,industrial heating and large scientific installations owing to their properties of high power,high efficiency,stability and so on.However,with the rapid development of the science and technology,especially in the applications of the large scientific facilities,including accelerators,colliders,controlled thermonuclear fusion reaction equipment,etc.,which requires the klystrons to be miniaturized,high power and high efficiency.Therefore,this dissertation innovatively combines metamaterials with extended interaction devices,and then carry out the study of theory,simulation and experiment about the metamaterial-inspired extended interaction oscillator(MEIO)and metamaterial-inspired extended interaction klystron(MEIK).The details include:research on the electromagnetic properties of metamaterials;study on the electromagnetic properties of metamaterial extended interaction resonante cavity(MEIRC),and the performance of MEIO and MEIK which use the MEIRC as the interaction structure in achieving miniaturization,high power and high efficiency.The main research contents and innovations of this dissertation are as follows:(1)The electromagnetic properties of metamaterials are investigated theoretically and simulation,and then the corresponding relationships among resonance properties,negative effective electromagnetic parameters,dispersion properties and transmission characteristics of metamaterial slow-wave structure are investigated.Firstly,the expressions of the effective electromagnetic parameters of material under test in different guided wave systems are derived theoretically,and then verified by using normal conventional materials.Based on this,a miniaturized and all-metal metamaterial unit cell is proposed,the effective consititutive parameters,high-frequency properties and transmission properties are studied by using time domain simulation of CST.Furthermore,a miniaturization coefficient is defined to characterize the miniaturization of metamaterials,and then the effects of miniaturization coefficients on dispersion characteristics are studied.It is shown that the miniaturization coefficient along the propagation direction of electromagnetic wave plays a decisive role in the dispersion of the metamaterials slow-wave structure.And the miniaturization coefficient in the vertical propagation direction mainly affects the dispersion passband deviation.(2)The theorey,simulation and experimental studies of metamaterial units filled with hollow circular waveguides are carried out.Especially,the high frequency characteristics of a metamaterial slow-wave structure composed of a circular waveguide loaded complementary electric split ring resonator(Ce SRR)array are studied by using the equivalent circuit method.The influence of structural parameters of Ce SRR element and cavity on high frequency characteristics is analyzed by dispersion equation and coupling impedance equation.On this basis,the experimental study of transmission of metamaterial slow-wave structure is carried out.The simulation and experimental transmission characteristics confirm the transmission passband provided by the negative effective refractive index of metamaterials,that is,the transmission passband operating below the cutoff frequency of the TM01 mode of the circular waveguide.The law of improving the high frequency properties and transmission characteristics of the metamaterials slow-wave structure is investigated.In particular,the main factors affecting the metamaterials slow-wave structure and the electromagnetic characteristics of MEIRC are discussed,which provide a theoretical and experimental basis for the further study of MEIO and MEIK.(3)A design scheme of low voltage MEIO with miniaturization and high electronic efficiency is proposed.The mode distribution of a multigap extended interaction cavity filled with metamaterial units is studied.A compact and low voltage MEIO operating in S-band is proposed based on the normalized electron load conductance and power exchange function.Its transverse and longitudinal dimensions are ～0.2λ and ～0.72λ(λis corresponding wavelength in free space),respectively.At the same time,a MW-level MEIO in S-band is proposed,and the influence of different gap numbers on MEIO output power is studied.Also,a method of inhibiting electron reflux while improving electronic efficiency is analyzed.Finally,a MEIO operating at 2.866 GHz with an output power of 4.9 MW and an electronic efficiency of 46% is realized,and its transverse and vertical dimensions are 0.35λ and 1.71λ,respectively.(4)A miniaturized and high electronic efficiency MEIK is proposed by the simulation and cold test experiments.The electromagnetic characteristics of the MEIRC are studied by calculation and simulation,and the potential advantages of MEIRC in terms of structure size and electromagnetic characteristics are analyzed.Furthermore,the cold test experiment of the 2-cavity MEIK was carried out,and the miniaturization characteristics of MEIK were confirmed by experiments.The simulation study of a3-cavity MEIK is further investigated.A saturated output power of 56 k W,an electronic efficiency of 62% and a saturated gain of 47 d B are obtained in the S-band.Finally,the stability of the MEIK,the focused magnetic field and the potential high voltage breakdown risk caused by the miniaturization of the structure are discussed.(5)A kind of miniaturization and high power MEIK for accelerator system are investigated and the corresponding technical scheme are put forward according to the application requirements.The results show that the diameter of the 650 MHz 3-cavity MEIK is about 0.33λ,which is about 2/3 of that of conventional counterparts.The saturate output power is 651 k W,the electronic efficiency is 52.8%,and the saturate gain is 35 d B when the length is less than 1.5 m.In addition,a 5-cavity metamaterial-inspired klystron operating at 2.856 GHz with a cavity diameter of 0.33λis studied.Under the conditions of 125 k V beam voltage,beam current of 80 A,focusing magnetic field of 0.2 T and input power of 18 W,the output power is 6.2 MW,the corresponding electronic efficiency exceed 60%,and the saturation gain is 55 d B.Finally,the hot-test experiment of the proposed high-power klystron was carried out.Under the conditions of electron beam voltage and current of 120 k V and 80 A,the output power was greater than 4 MW in the frequency range of 2.852 GHz-2.858 GHz.The maximum output power is 5.51 MW at 2.8523 GHz,the saturation gain is 54.9 d B,and the corresponding electronic efficiency is 57.4%.更多还原