多注耦合腔行波管互作用均匀性研究

对多注行波管慢波结构的特性进行了模拟与分析,利用粒子模拟方法,定量模拟了多注行波管的PIC注波互作用过程,通过比较不同电子注位置情况下电场E的振幅、相移、非线性和互作用效率,研究了多注电子注波互作用的均匀性特点,发现电子注位置不同时对电场有不同的影响,这对实际多注耦合腔行波管设计有一定指导意义。     

双槽型耦合腔行波管非线性注波互作用计算方法

建立了双槽型耦合腔行波管三维频域非线性注波互作用模型,推导出参与注波互作用电磁场及粒子运动方程组。根据模型与方程组编写非线性互作用计算程序,模拟注波互作用过程,得到输出功率、增益等性能参数。计算结果与X波段双槽型耦合腔行波管实测数据比较,以验证计算方法的准确性,并对互作用过程中的非线性现象进行分析,希望能够辅助行波管的设计。     

一种高效率多注毫米波行波管的设计模拟

对某Ka波段7注耦合腔行波管慢波系统进行了模拟,分析了多注耦合腔行波管的单腔冷测特性、周期永磁聚焦（PPM）系统以及PPM聚焦系统下的注-波互作用,模拟结果表明：在中心频率34.5GHz处,其饱和输出功率达到829W,增益43.16dB,带宽约1.4GHz,电子效率高达30.37%。     

C波段10%大工作比栅控耦合腔行波管

介绍了一只C波段10%大工作比栅控耦合腔脉冲行波管的研制情况。通过对电子枪、慢波电路等的科学合理设计,并应用CAD模拟技术和2.5维大信号注波互作用程序进行模拟改进,短期内研制出符合要求的合格管。研制结果表明:该管在14%的相对带宽内等激励时的脉冲输出功率均大于12 kW,效率大于20%,增益大于49 dB。     

脊加载环板行波管高频特性的研究

脊加载环板行波管是一种频带相对较宽的大功率行波管,本文用场匹配和变分原理相结合的方法,研究了脊加载环板慢波结构的导波特性及这种行波管的小信号、大信号特性,讨论了结构的几何尺寸及电子注参量对慢波的传播特性、小信号增益及注-波互作用非线性效应的影响.本文的结果将为脊加载环板行波管的设计提供理论基础.     

分布损耗回旋行波管线性分析与稳定性研究

研究了分布损耗材料导电特性的下降能够增强回旋行波管注-波互作用段对电磁波的衰减,提高了绝对不稳定性振荡的起振电流和竞争模式回旋返波振荡的起振长度;但同时减小了回旋行波管的线性增长率及其轴向功率和高频场增益.给出了石墨乳涂敷圆波导结构回旋行波管工作参数,采用电子束电流,I_0=10A、注-波互作用段长度L=10cm时的设计结果,在兼顾功率和增益的条件下,能够有效抑制不稳定性,保证其稳定工作.     

脊加载环板行波管的理论与实验研究

脊加载环板行波管是一种频带相对较宽的大功率行波管 ,本文对脊加载环板慢波系统及其改进型进行了研究 ,理论与实验良好符合 ,实验表明脊加载环板慢波系统的改进型比脊加载环板慢波系统具有更宽的频带 ;同时对慢波系统采用等效线路模型 ,电子注采用二维圆环模型 ,研究了脊加载环板行波管的大信号特性 ,讨论了注波互作用的非线性效应。本文的结果将为脊加载环板行波管的设计提供理论基础。     

W波段V型曲折矩形槽波导行波管的模拟研究

分析了一种新型慢波线-V型曲折矩形槽波导慢波结构,利用电磁仿真软件CST及HFSS对其高频特性进行了模拟计算,并在此基础上设计了工作在W波段的V型曲折矩形槽波导行波管的互作用结构.利用CST粒子工作室对其注-波互作用特性进行了模拟分析.结果表明:W波段V型曲折矩形槽波导行波管能够有效放大微波信号,且频谱纯净.     

W波段阶梯型交错双栅慢波结构行波管的研究

为了提高传统交错双栅慢波结构行波管的性能,提出了一种阶梯型交错双栅慢波结构,并基于此新型慢波结构,提出了新型输入输出耦合结构.在此基础上,设计了一只工作在W波段的带状电子注阶梯型交错双栅慢波结构行波管.计算结果显示,阶梯型交错双栅慢波结构行波管的耦合阻抗更高,从而使行波管在更短的互作用电路长度里,实现更高的饱和增益和互作用效率.在90～100GHz频率范围内,阶梯型交错双栅慢波结构的耦合阻抗大于4Ω,高于传统交错双栅慢波结构;W波段带状电子注行波管高频结构的反射系数(S11)小于-15dB;并且行波管的饱和输入功率仅约为0.7W,可以实现最高输出功率约800W,相应的效率大于7.8%,增益大于30.6dB.     

强耦合式带状注速调管多间隙输出腔的设计

提出了一种强耦合式带状注速调管多间隙输出腔, 并将之应用于Ka波段带状注速调管输出腔的设计. 此设计可以获得更好的输出耦合特性和理想的场形. 更重要的是, 这种结构的漂移管允许被设计为对工作频率的截止状态, 从而可以获得更理想的电场场形以利于注波互作用. 从表面电流的角度分析了这种设计的理论依据. 通过使用粒子模拟软件进行仿真, 在中心频率获得了稳定的功率输出, 互作用效率达到50%以上, 3dB带宽约75MHz.     

耦合腔行波管腔长渐变对电子效率的影响

为了进一步提高耦合腔行波管(CCTWT)的电子效率,需要可以计算CCTWT的大信号程序。本文叙述了利用程序CCTaper计算CCTWT腔长渐变对电子效率的影响情况。     

Parametric Simulation and Optimization of Cold-test Properties for a 220 GHz Broadband Folded Waveguide Traveling-wave Tube

Characterized with full-metal structure, high output power and broad bandwidth, microfabricated folded waveguide is considered as a robust slow-wave structure for millimeter wave traveling-wave tubes. In this paper, cold-test (without considering the real electron beam) properties were studied and optimized by 3D simulation on slow-wave structure, for designing a 220 GHz folded waveguide traveling-wave tube. The parametric analysis on cold-test properties, i.e., phase velocity, beam-wave interaction impedance and cold circuit attenuation, were conducted in half-period circuit with high frequency structure simulator, assisted by analytical model and equivalent circuit model. Through detailed parametric analyses, interference between specified structural parameters is found on determining beam-wave interaction impedance. A discretized matrix optimization for interaction impedance was effectively carried out to overcome the interference. A range of structural parameters with optimized interaction impedance distributions were obtained. Based on the optimized results, a broadband folded waveguide with cold pass-band of about 80 GHz, flat phase velocity dispersion and fairly high interaction impedance was designed for a 220 GHz central frequency traveling-wave tube. A three-dB bandwidth of 20.5 GHz and a maximum gain of 21.2 dB were predicted by small signal analysis for a 28 mm-long lossy circuit.     

MAGIC3D Simulations of a 500-W Ka-Band Coupled-Cavity Traveling-Wave Tube

The 3-D particle-in-cell (PIC) simulations of a Ka-band coupled-cavity traveling-wave tube (CCTWT) are shown. The computational analysis of the Ka-band coupled-cavity slow-wave structure was conducted through the use of an electromagnetic PIC code MAGIC3D. The choice of a double-slot staggered RF cavity circuit was made because of a wide frequency bandwidth, moderate interaction impedance, and excellent thermal dissipation properties. We investigated the large-signal and nonlinear beam dynamics of a Ka-band CCTWT using MAGIC3D. The center frequency of the Ka-band CCTWT can be tuned from 28.4 to 30 GHz by varying the cathode voltage. Hot-test simulations show that the 84-cavity Ka-band CCTWT produces 540 W of saturated output power at 29 GHz with an electronic efficiency of 8.1% and a gain of 28 dB when the beam voltage and current are set to 17 kV and 390 mA, respectively.      

Design of high-efficiency wide-bandwidth coupled-cavitytraveling-wave tube phase velocity tapers with simulated annealingalgorithms

The output circuit section of a traveling-wave tube (TWT) routinely contains an RF phase velocity taper for the purpose of increasing RF output power and efficiency. By slowing the RF phase velocity in approximate synchronism with the decelerating electron beam bunches, the taper increases power transfer from the beam to the RF wave. Recently, the computational optimization technique of simulated annealing was shown to be very effective in the design of an RF phase velocity taper that significantly increased computed RF power and efficiency of a coupled-cavity TWT. In this paper, two new broadband simulated annealing algorithms are presented that optimize (1) minimum saturated efficiency over a frequency bandwidth and (2) simultaneous bandwidth and minimum efficiency over the frequency band with constant input power. The algorithms were incorporated into the NASA 2.5-dimensional (2.5-D) coupled-cavity TWT computer model and used to design optimal phase velocity tapers using a 59-64 GHz coupled-cavity TWT as a baseline model. Compared to the baseline taper design, the computational results of the first broadband algorithm showed an improvement of 73.9% in minimum saturated efficiency. The second broadband algorithm indicates an improvement of 272.7% in minimum RF efficiency with constant input power drive and an increase in simultaneous bandwidth of 0.5 GHz over that calculated for the baseline TWT     

卷绕双梳齿行波管中注-波互作用的研究

本文利用CST 软件中的粒子工作室对采用卷绕双梳齿慢波结构的圆极化行波管中的注-波互作用情况进行了粒子模拟研究,观察了电子束的运动情况,同时得到了电压、电流、磁场和输入功率四个重要电气参数对输出功率的影响。研究结果为圆极化行波管的设计奠定了理论基础。     

Simulation of cold-test parameters and RF output power for acoupled-cavity traveling-wave tube

Procedures have been developed which enable the accurate computation of the cold-test (absence of an electron beam) parameters and RF output power for the slow-wave circuits of coupled-cavity traveling-wave tubes (TWT's). The cold-test parameters, which consist of RF phase shift per cavity, impedance, and attenuation, are computed with the three-dimensional electromagnetic simulation code MAFIA and compared to experimental data for an existing V-band (59-64 GHz) coupled-cavity TWT. When simulated in cylindrical coordinates, the absolute average differences from experiment are only 0.3% for phase shift and 2.4% for impedance. Using the cold-test parameters calculated with MAFIA as input, the NASA Coupled-Cavity TWT Code is used to simulate the saturated RF output power of the TWT across the V-band frequency range. Taking into account the output window and coupler loss, the agreement with experiment is very good from 60-64 GHz, with the average absolute percentage difference between simulated and measured power only 3.8%. This demonstrates that the saturated RF output power of a coupled cavity TWT can be accurately simulated using cold-test parameters determined with a three dimensional electromagnetic simulation code     

The Beam-Wave Interaction in a Ka-Band Relativistic Coupled-Cavity TWT

By the method of the eigen mode expansion, a full three-dimensional (3-D) model has been developed that can be used to investigate the beam-wave interaction in a high-power, Ka-band relativistic coupled-cavity traveling-wave tube (TWT). In the tube studied by us, a sever in the interaction section is used to restrain the oscillation of RF electromagnetic fields between the input and output end. In this case, the asymmetric hybrid HTM₁₁ mode has little impact on the main interaction process ^[1,2], so the RF electromagnetic fields mainly interacting with the modulated electron beam belong to the symmetric mode TM₀₁. The presented model includes three-dimensional RF fields, three-dimensional electron motions, and improved three-dimensional space-charge fields including dc and ac space-charge fields. Moreover, this model can also calculate backward radiation excited by modulated electron beam and the direct effect of the transverse electron motion on the energy exchange. Our calculation results show that the space-charge field has evident effect on the interaction process, the transverse electron motion has some, and the backward radiation has little.     

W波段回旋行波管仿真设计与热测实验

通过软件仿真方法分析和设计了W波段回旋行波管的输入输出耦合器、磁控注入式电子枪以及高频互作用电路,根据优化结果加工了实物并进行了热测实验.实验结果表明,电子注电压60 k V,电流6 A,在94 GHz频率获得了最大峰值功率78 k W,增益53.9 d B以及21.7%的效率,峰值功率大于50 k W带宽达到3.8 GHz.PIC粒子模拟和热测实验均表明,设计的W波段回旋行波管能够稳定的工作,从而证明周期加载高频互作用电路在抑制寄生模式以及自激振荡方面具有很大的优势.