Ka波段曲折双脊单槽加载波导行波管研究

提出了一种新型的曲折波导慢波结构:曲折双脊单槽加载波导慢波结构.利用HFSS、CST电磁仿真软件对工作在Ka波段的曲折双脊单槽加载波导行波管进行了模拟计算,得到其高频特性及注-波互作用特性.结果表明,在33 GHz可以得到265 W的输出功率,增益为37.2 dB,3 dB增益带宽为6 GHz.     

0.14 THz双注折叠波导行波管的高频系统设计

随着太赫兹通信技术的发展,对于0.14 THz折叠波导行波管(FWTWT)的研究需求向着更高的功率和更宽的带宽发展。对双注行波管中的双路折叠波导慢波电路进行分析,得到不同参数下的高频特性变化规律。并对双路折叠波导慢波电路的功率分配和功率合成效率进行分析计算,得到功率合成效率96.3%。最后对双路慢波电路、功率分配/合成器和集中衰减器进行建模,并对注波互作用进行计算。在高压15 kV和单注电子的发射电流为40 mA条件下,得到0.14 THz频率下的合成输出功率为56 W,增益为31.4 dB,3 dB带宽为7 GHz。     

W 波段行波管的高效率方法

将相速再同步技术引入基于双排矩形梳状慢波结构的W波段行波管中,利用CST 计算了所需不同周期的慢波结 构的色散和偶合阻抗,在此基础上用MTSS 模拟计算了注波互作用。结果证实：对于由两段周期均匀的慢波结构构成的 W波段行波管,在90~98GHz 范围内输出功率为48.92W~56.44W,电子效率为6.04%~6.96%,增益大于49dB;而对于由 7 段周期跳变的慢波结构构成的W波段行波管,在90~98GHz 范围内输出功率为57.06W~98W,电子效率为6.98%~11.99%, 增益大于50dB;两者相比,电子效率提高1%~4%。     

多注太赫兹折叠波导行波管的设计与模拟

为解决太赫兹(THz)行波管工作电流过小、输出功率低等问题,提出了基模多注工作模式的折叠波导行波管(TWT)。首先,获得了基模多注折叠波导色散特性;然后,对基模多注折叠波导的传输特性进行了模拟计算;最后,完成了0.14 THz基模多注折叠波导行波管的注波互作用特性分析。电子注参数为12 m A,15.75 k V时,获得的3 d B带宽为25 GHz(128 GHz~153 GHz),最大增益为33.61 d B,最大峰值功率为23 W;电子注参数为30 m A,15.75 k V时,在0.14 THz处获得了38 d B增益,最大脉冲输出功率为63.1 W。该方法能够有效增大THz行波管的工作电流,提高互作用增益及效率、3 d B带宽、输出功率;在增益相同时,基模多注行波管可以做得更短、更紧凑。     

太赫兹翼片加载折叠波导行波管放大器的研究

翼片加载折叠波导电路是一种改进型的行波管互作用电路。与原始结构相比,它具有提高的耦合阻抗、扩展的横向尺寸以及更加灵活的设计能力,因此适合工作在太赫兹频段。首先采用理论模型设计了工作频率0.22THz的慢波结构;然后采用三维粒子模拟技术对翼片加载折叠波导行波管放大器的非线性性能进行了研究。结果显示,新型结构具有高的互作用效率和宽频带放大的能力。在中心工作频率220GHz处,2mW的驱动功率下可以得到4W的饱和输出功率,对应的电子效率和增益分别为2.47%和33dB（考虑了电路的导体损耗）;恒定功率下扫频模拟显示,放大器的瞬时3dB带宽可达13.6,频率范围覆盖205～235GHz。     

0.22 THz宽带折叠波导慢波结构的设计

通过对折叠波导的理论分析,提出一种快速设计折叠波导慢波结构的方法。优化设计了中心频率为0.22 THz的折叠波导慢波结构,分析了结构参数对高频特性的影响。为防止振荡,仿真中采用截断的慢波结构。互作用仿真表明,在电子注电压为16 kV,电流为10 mA情况下,中心频率处增益为23.9 dB,输出功率为1.2 W。其中3 dB带宽大于14 GHz(0.214 THz~0.228 THz),带内输出功率大于0.5 W,在7 GHz(0.217 THz~0.224 THz)范围内输出功率大于1 W。     

E波段折叠矩形槽波导行波管的研究

分析了一种适用于E波段81~86 GHz空间行波管的新型慢波结构——折叠矩形槽波导.折叠矩形槽波导来源于传统的矩形槽波导,将E面沿其纵向来回弯曲而形成.利用电磁场仿真软件Ansoft HFSS设计优化并最终确定了E波段折叠矩形槽波导的关键几何尺寸.同时,模拟仿真出了折叠矩形槽波导在中心频率f=83.5 GHz处的耦合阻抗沿x和y方向上的变化趋势,得出其可通过加载带状电子注获得更高的平均耦合阻抗.利用CST粒子工作室模拟得出:折叠矩形槽波导行波管在中心频点83.5 GHz处输出功率为210 W,电子效率达到8.05%.     

0.41 THz折叠波导慢波结构分析与设计

在0.14 THz,0.22 THz和0.34 THz折叠波导行波管研制的基础上,讨论了0.41 THz折叠波导行波管慢波结构设计与加工的可行性,分析研究了折叠波导慢波结构弯曲处直角弯曲与半圈弯曲、方形电子注通道与圆形电子注通道对色散特性、耦合阻抗、带宽、冷损耗和增益的影响。考虑了慢波结构中增加理想衰减器对该行波管带宽和增益的影响,得到了0.41 THz折叠波导行波管慢波结构的初步设计方案,为太赫兹折叠波导行波管的继续发展打下了一定基础。     

0.14 THz大功率回旋行波管前级激励源粒子模拟研究

以折叠波导行波管作为大功率回旋行波管的前级激励信号源,利用电磁仿真软件HFSS和粒子模拟软件(CST粒子工作室),对0.14 THz微电真空折叠波导行波管慢波结构的色散特性、耦合阻抗进行计算分析,然后对折叠波导行波管束波互作用过程进行粒子模拟,最后通过粒子模拟得到该折叠波导行波管的增益、工作电压、电流等工作特性参数。在电压为13.9 kV、电流为16 mA,输入功率为5 mW的条件下,输出功率为5 W,线性增益为30 dB,带宽3.7 GHz,最大输出功率为6.2 W,该结果为0.14 THz大功率回旋行波管实现kW量级的功率输出提供功率足够的前级馈入信号奠定了基础。     

电子注通道形貌对折叠波导慢波结构的影响

折叠波导结构是一种极具潜力的太赫兹行波管慢波电路.分析了电子注通道形貌对折叠波导高频特性的影响,包括色散特性、耦合阻抗和衰减特性.仿真结果表明,相比于圆形电子注通道,矩形电子注通道的折叠波导结构色散要略微陡一些,损耗也要略微高一些.在中心频率处,矩形电子注通道结构的耦合阻抗比圆形电子注通道结构低0.5Ω左右.皮尔斯小信号理论表明,在中心频率处,矩形电子注通道结构和圆形电子注通道结构的增益速率分别为4.85 dB/cm和5.22 dB/cm,具有相似的3 dB带宽,约为6.3 GHz和7.2 GHz.粒子模拟表明,对于矩形和圆形电子注通道,54 mm(100个周期)的折叠波导慢波结构在220 GHz增益分别为24.42 dB和28.44 dB.     

0.14 THz折叠波导行波管的设计与实验

对折叠波导慢波结构进行了研究,对其色散特性和耦合阻抗进行分析,并设计了输能窗和电子光学系统,在此基础上进行了粒子模拟的束波互作用计算。通过设计,对0.14 THz 行波管进行了制管工艺的研究,包括慢波结构的加工和焊接等,完成了热测实验。在电压为16.3 kV,电子流通率为74%条件下,测试得到最大饱和输出功率3.1 W,输出频率140.08 GHz,增益27 dB,最大功率半带宽2.82 GHz。     

D波段7 W连续波折叠波导行波管的研制

介绍了一种D波段连续波行波管放大器。该行波管采用了高压缩比皮尔斯会聚电子枪、折叠波导慢波结构(FWSWS)、蓝宝石输能盒形窗、周期永磁聚焦系统、集中衰减器以及一级降压收集极,经过装配、焊接、排气、磁场调试等过程,得到了D波段连续波放大器样管,并进行了流通率的调试和信号放大的测试。实验测试结果为：电子电压15.4 kV,电子流通率97%时,连续波输出功率7.3 W,中心频率140.2 GHz,增益24.6 dB,3 dB带宽3 GHz。该放大器连续运行稳定,满足工程化要求。     

Nonlinear analysis of a multi-cavity gyro-twystron

To preserve high gain, high efficiency and high power merits of gyroklystron, a gyro-twystron is designed using an electron beam with α(v_⊥/v_z) greater than unity. With a multi-cavity section of high gain, the length of the waveguide output section can be made shorter than the threshold length of the absolute instability without losing total system gain. Numerical simulations are carried out to analyze a ka-band gyro- twystron consisting of three TE₁₁₁ mode cavities and an output section of a TE₁₁ mode waveguide. Stability study is performed to ensure the tube without self-excited oscillations. With α=1.5, the 3-dB linear and saturated gain bandwidth in excess of 2 % can be obtained by stagger tuning for an 80 kV, 3 A electron beam with 5 % axial velocity spread. The maximum saturated gain is more than 55 dB at 33 % efficiency. By tapering the magnetic field of the last 2 cm of the interaction region, the efficiency can be increased to 43 % without degrading the bandwidth, which corresponds to an output power of 103 kW.     

梯形结构高功率扩展互作用速调管

对平面梯形结构多间隙谐振腔的模式分布、特性阻抗、耦合系数以及工作稳定性进行了研究.在此基础上给出了W波段高峰值功率扩展互作用速调管高频互作用系统设计,并采用三维粒子模拟(PIC)技术对电子的速度调制、群聚及其与高频场的相互作用和能量转换等物理过程进行了研究,定量给出了放大器的功率、带宽、效率以及增益等关键技术指标.PIC结果显示:在中心频率94.52 GHz以及电压16 k V、电流0.6 A的电子注参数下,最大输出功率达到1.8 k W,相应的增益和电子效率分别为47.7 d B和19.4%;扫频结果显示瞬时3 d B带宽为210 MHz.     

Analysis and Numerical Calculations of the Beam-Wave Interaction for Gyroklystron Amplifiers

A four-cavity gyroklystron was designed and optimized after analysis and calculation of RF system and magnetron injection gun, numerical simulations showed that the TE₀₁₁ mode gyroklystron achieved 280kW peak output power, 38% efficiency, 35dB saturated gain with 250Mhz bandwidth centered at 34GHz for a 68 kV, 11A electron beam. The numerical simulation results were used to build a Ka band high power gyroklystron amplifier. In this paper, analysis and numerical calculation results of the beam-wave interaction are presented. The influences of electron beam, RF system parameters, magnetic field, and input RF signal on output power, efficiency, bandwidth and gain are discussed.     

LARGE-SIGNAL SIMULATIONS OF A GYROTRON TRAVELING-WAVE AMPLIFIER WITH A MODE-SELECTIVE INTERACTION CIRCUIT

A self-consistent nonlinear theory is used to analyze the saturated performances of a Ka-band gyrotron traveling wave amplifier (gyro-TWA) operating at the fundamental with a mode-selective interaction circuit involving a tapered vane-slot mode converter. The amplifier is predicted to generate 140 kW saturated output power with 33.3% efficiency, a saturated gain of 33dB, and a 3dB bandwidth of 2.7 GHz (8%) for a 70 kV, 6A electron beam with a velocity ratio of 1.0 and an axial velocity spread of 5%.     

A 18 GHz Broadband Stacked FET Power Amplifier Using 130 nm Metamorphic HEMTs

A broadband power amplifier (PA) with a 3 dB power bandwidth of 72% is presented using metamorphic high electron mobility transistors (mHEMTs). A stacked FET structure, where transistors are series connected to combine voltage swings, is employed to overcome relatively low breakdown voltages of mHEMTs. Series-connected PA's show much higher load impedance compared to the parallel combined transistors, which allows output matching to be realized in the low quality (Q)-factor region, providing the broadband performance. The fabricated PA using quadruple-stacked 130 nm mHEMTs has a gain of 21.2 dB and saturated output power of 26.4 dBm with power added efficiency (PAE) of 33% at the design frequency of 18 GHz. The 3 dB output power bandwidth is from 10 to 23 GHz.      

A new grid-controlled pulse TWT with depressed collector

A grid-controlled pulse TWT with depressed collector and PPM focusing system is reported in this paper. It operates at X-band and delivers peak output power of 1 kW with saturation gain of 47 dB. The duty cycle is 3%. The electron beam transmission is 95% with RF output at saturated condition. The efficiency is not less than 30% (excluding the heater power).     

A 30-GHz 1-W power HEMT

Millimeter-wave power high electron mobility transistors (HEMT's) employing a multiple-channel structure have been fabricated and evaluated in the R-band frequency range. An output power of 1.0 W (a saturated output power of 1.2 W) with 3.1-dB gain and 15.6-percent efficiency was achieved at 30 GHz with a 0.5-µm gate-length and 2.4-mm gate-periphery device. At 35 GHz, a 2.4-mm device delivered 0.8 W with 2.0-dB gain and 10.7-percent efficiency. These are the highest output power figures reported to date for single-chip power FET's in the 30-GHz frequency range.     

Preliminary Design of a Harmonic-doubling Gyrotron Traveling Wave Amplifier

This study proposes a Ka-band harmonic-doubling gyrotron traveling-wave amplifier (gyro- TWT), using distributed wall losses in the input stage and mode-selective interaction circuit in the output stage, to improve the stability of the amplification. Based on a large signal simulation code, a saturated peak power of 163 kW with an efficiency of 15.5%, a gain of 31.1 dB, and a 3 dB bandwidth of 0.9 GHz is predicted for the gyro-TWT driven by 70 kV, 15 A electron beam with a velocity ratio of 1.2 and velocity spread 5% at 33.2 GHz.