Q波段回旋行波管宽带高平均功率输出窗设计与热分析

利用场匹配理论建立传输级联矩阵的方法对多层窗片结构输出窗进行研究,通过大量的数值计算给出Q波段回旋行波管一种新型中间风冷结构输出窗的参数,然后通过数值计算和HFSS仿真验证,该新型输出窗在46~50GHz范围内,S11反射系数小于-20dB。在此基础上进一步对该输出窗进行热分析,热分析表明:新型输出窗窗片中心与边缘温差与传统输出窗相比大幅下降,热应力大大减小,提高了输出窗的功率容量。回旋行波管工作在TE01模式时,新型输出窗获得的最大饱和功率容量达到90kW,与传统输出窗相比,功率容量提高了21.8kW。     

3mm回旋行波管微波等离子体化学气相沉积金刚石输出窗

为了解决目前3mm回旋行波管所使用的蓝宝石输出窗因功率容量不足而发生破裂的问题。从抗热震性和功率容量两个方面出发,对常用的几种窗片材料进行了对比。在国内首次以微波等离子体化学气相沉积金刚石为窗片材料,利用数值计算及ANSYS软件仿真设计了用于3mm回旋行波管的低反射,低吸收,宽带宽,高功率容量的输出窗。结果表明,所设计的输出窗适用于TE01模式输出,其S11参数小于-20dB的带宽为6GHz。同时,该输出窗具有良好的抗热震性,在自然对流散热条件下具有61kW的功率容量。     

L波段大功率全带宽波导盒型窗

 由于鬼模振荡的存在,普通波导盒型窗很难获得宽频带输出,其相对带宽一般只有20%～30%。提出一种新的适用于大功率螺旋线行波管非对称全带宽波导盒型窗设计思路,通过３维电磁仿真设计与优化,获得了L波段相对带宽达41.4%盒型窗结构设计参数,且频带内无鬼模振荡,考虑匹配过渡段后整个盒型窗驻波系数模拟计算小于1.1。采用此功率输出结构研制的S波段大功率行波管连续波输出功率达3 kW以上,整管实测驻波系数小于1.6。     

低反射低吸收高平均功率输出窗的设计

 对高平均功率微波、毫米波输出窗的反射和吸收功率进行了理论分析，以蓝宝石输出窗为例，给出了低反射、低吸收的高平均功率回旋速调管放大器输出窗的设计方案。该放大器输出窗厚度为1.35mm，半径为9mm，工作频率为34GHz，在加工误差小于2%的情况下，输出窗反射率小于1%，当平均输出功率为10kW时窗片的吸收功率为2.5W。     

105/140 GHz双频兆瓦级回旋管的设计与实验进展

介绍了105/140 GHz双频兆瓦级回旋管的设计和最新实验进展。该回旋管的谐振腔、准光模式变换器、BN输出窗采用了双频共用的设计,电子枪采用了双频复用的双阳极磁控注入枪,收集极采用单级降压。在现有实验室电网功率容量有限的情况下,进行脉冲调试,得到的实验结果为:在重频1 Hz、ms连续短脉冲条件下,在105 GHz点和140 GHz点脉冲功率分别达到710 kW和1.057 MW,脉宽0.7 ms,对应总效率分别为34%和49%。在105 GHz点通过脉宽延展和老炼,进一步得到300 kW/2 s和400 kW/1 s的秒级脉宽实验结果,BN窗片的温度在两种状态下温度分别达到606℃和503℃,波束频率单一,没有杂模。实验基本上验证了该器件的物理设计。     

圆柱盒型窗的连续波功率容限问题的研究

 运用精确的解析推导方法对圆TE₁₁模微波窗的额定平均功率公式做了修正，给出了圆柱盒型窗中介质窗片温升的具体计算方法，并结合实际问题对圆柱盒型窗用于传输高功率连续波时的功率容限和鬼模振荡的特殊危害性以及排除方法进行了详细的讨论。研究结果表明：在L波段，只要排除工作频带内的鬼模，普通圆柱盒型窗用于传输120~150kW的连续波不成问题，并且可以得到14%左右的相对带宽。     

W波段回旋行波管放大器的模拟与设计

回旋行波管放大器是高功率毫米波雷达发射系统最重要的候选者.通过对回旋行波管放大器中的绝对不稳定性、回旋返波振荡以及电子注-波互作用的研究，讨论了回旋行波管的稳定性、寄生模式的抑制和工作参数的优化等问题，给出了W波段TE₀₁模回旋行波管放大器的模拟设计结果.PIC粒子模拟结果表明，在电子注电压100kV、电流10A、工作磁场3.52T时，94GHz的基波回旋行波管放大器可获得大于250kW的输出功率、40dB的增益、大于25％的效率和约5％的带宽. 关键词： W波段 回旋行波管放大器 模拟 设计     

W波段螺旋波纹波导回旋行波管注波互作用的非线性分析

回旋行波管是下一代高分辨率成像雷达、高速率远程通信等电子系统首选的高功率电磁波辐射源,在国防安全方面具有重要的战略意义,研究发现,螺旋波纹波导回旋行波管具有较大的带宽,较高的电子效率及稳定性,本文从有源麦克斯韦方程组出发,系统地推导了螺旋波纹波导的色散方程及非线性注波互作用理论,数值计算结果与已有的实验报道基本相符,在此基础上,设计了W波段螺旋波纹回旋行波管,工作电压为80kV,工作电流为5A,中心频率为95GHz,3dB带宽约4.5%,饱和增益为52dB,最大输出功率为142kW,电子效率达20%—35%.最后,本文计算了电流、电压及输入功率的改变对W波段螺旋波纹波导回旋行波管输出性能的影响。     

0.34 THz双注高次模折叠波导行波管高频系统设计

高频系统是行波管的核心部件,它会直接影响行波管的工作频率、带宽、增益等性能指标。为了获得更大的输出功率和更高的增益,对0.34 THz双注高次模折叠波导行波管的基本特性进行了研究,计算了双注折叠波导的色散特性和耦合阻抗,并与仿真结果进行对比,结果显示色散特性随频率升高差距增大,耦合阻抗在高频段匹配较好,并研究了损耗特性。利用CST仿真工作室对双注折叠波导的注波互作用特性进行了仿真,实现41.68 W输出。为了获得更高的输出,通过增大直波导高度,最终使输出功率提高了52.7%,达到63.12 W。最后设计了符合要求的盒型输出窗和模式转换器,验证了高频系统的传输特性。     

8mm基波回旋行波管放大器的设计

对8 mm基波回旋行波管放大器进行了研究。通过稳定性分析,选定了放大器的工作参数。利用PIC粒子模拟程序对放大器中的电子注-波互作用过程进行了详细的分析和讨论,获得了回旋行波管稳定工作的物理图像,完成了8 mm基波回旋行波管放大器高频系统的初步设计。模拟结果表明,在优化设计条件下,放大器可以获得大于450 kW的输出功率5、0 dB增益、22.5%的效率和大约5%的3 dB带宽。     

分布损耗加载回旋行波管多模稳态注波互作用理论与比较证实

基于目前国际上实验研究的均匀介质加载和周期介质加载结构,建立了一种分布式损耗加载回旋行波管(gyro-TWT)多模稳态注波互作用理论.利用这一理论,以TE01模式基波gyro-TWT注波互作用为例,将Ka和W波段的理论结果与实验和软件仿真进行比较,以证实理论的合理性.     

High-power harmonic gyro-TWT's. II. Nonlinear theory and design

For pt.I, see ibid., vol.20, no.3, p.155-162 (1992). Based on an analytical study of the stability problems of gyrotron traveling wave amplifiers (gyro-TWTs), an extremely high power second-harmonic gyro-TWT has been designed, evaluated and optimized with a self-consistent nonlinear numerical simulation code. The design, which is based on the magnetron-injection-gun (MIG)-type beam, is presented. Using a 100 kV, 25 A MIG beam with α=1 and an axial velocity spread of 5%, nonlinear self-consistent analysis of a three-stage second-harmonic gyro-TWT amplifier predicts a peak output power of 533 kW, peak efficiency of 21.3% and a 7.4% saturated bandwidth, which verifies the theoretical predictions that a stable harmonic gyro-TWT can generate power levels an order of magnitude higher than those possible from a fundamental gyro-TWT. It is shown that the positioning of the electron beam is very important. A multistage structure is used to recover the loss in gain resulting from shortening the interaction sections to ensure stability     

一种高功率宽带回旋行波放大器

 研究了一种X波段高功率宽带回旋行波放大器，它由改变了局部周期的矩形盘荷波导组成，并采用锥化引导磁场和盘的高度来提高增益和带宽。分析了器件的线性特性。利用全电磁（PIC）三维模拟程序EMC进行了数值模拟，结果表明：可以得到功率介于88~103kW，相对带宽介于16.63%~24.11%的不同微波输出。     

Theory and experiment of ultrahigh-gain gyrotron traveling waveamplifier

Physics and technology issues of importance to the high-gain gyrotron traveling wave amplifier (gyro-TWT) are investigated in theory and experiment. The gyro-TWT is known to be highly susceptible to spurious oscillations, especially in high gain operations. In the current study, oscillations of various origins are classified and characterized with detailed theoretical modeling. They are shown to be intricately connected to the interplay between the absolute/convective instabilities, circuit losses, and reflective feedback. Knowledge of these processes leads to the concept of an ultra high gain scheme which employs distributed wall losses for the suppression of spurious oscillations. A proof-of-principle Ka-band gyro-TWT experiment stable at zero drive has produced 93 kW saturated peak power at 26.5% efficiency and 70 dB gain, with a 3 dB saturated output power bandwidth of 3 GHz. The saturated gain is more than 30 dB beyond that previously achieved     

Optimum Design for RF Windows in Millimeter Wave High Power Tubes

The pill-box and block RF windows for millimeter wave (MMW) tubes are presented. The pill-box window is suitable for broadband MMW tubes. And the block window can be used for high power tubes in short MMW. The equivalent circuits for two windows are given. To reach better match characteristics in wider operating bandwidth, the optimum design methods for pill-box and block window in MMW tubes are described in this paper. The testing results show that the theoretic computation is fast and useful accuracy. The design methods possess references value to designer for MMW tubes.     

Large-signal characteristics of a wide-band dielectric-loadedgyro-TWT amplifier

The bandwidth of a gyrotron traveling wave amplifier (gyro-TWT) has been significantly increased by partially filling the interaction waveguide with dielectric to reduce the circuit's dispersion. The proof-of-principle experiment was designed for X-band, and employs the fundamental mode of rectangular waveguide loaded with dielectric slabs along the narrow sidewalls. The amplifier yields a peak output power of 55 kW with 11% efficiency, 27 dB saturated gain, and an unprecedented untapered gyro-TWT constant-drive bandwidth of 11% and saturated bandwidth exceeding 14%. The single-stage amplifier is completely zero-drive stable. The 95-kV 5-A electron beam was produced by a single-anode magnetron injection gun with p_⊥/υ_z=0.6, as determined by the EGUN code, and Δυ_z/υ_z=4%, determined as the best fit to the gyro-TWT large-signal simulation data. Simulation studies predict that by lowering the velocity spread to Δυ _z/υ_z=2%, the amplifier performance will be further enhanced to a constant-drive bandwidth of 20% with 15% efficiency