W波段二次谐波回旋行波管放大器

采用谐波工作的回旋管互作用磁场比基波磁场降低了1/s,可降低整管磁场设计难度,具有较大的应用前景。通过对W波段二次谐波回旋行波管高频介质加载结构、模式竞争和注波互作用研究,确定了该放大器的工作参数。非线性模拟表明,当应用100 kV,20 A,α=1.2的电子注时,该回旋管可在91 GHz频率处产生465 kW的输出功率和49 dB的增益结果。并且,基于耦合波理论,讨论了一个轴对称半径微扰的TE02~TE01输出模式变换器,效率在95%以上时,其带宽达到4 GHz。     

Ka波段二次谐波回旋速调管放大器的PIC模拟

该文根据谐波回旋速调管放大器的注.波互作用特点,分析了放大器稳定工作的条件:对Ka波段二次谐波三腔回旋速调管放大器的注-波互作用进行了模拟计算,对放大器的注.波互作用电路参数进行了优化设计。模拟计算结果表明,在电子注电压为70kV,电子注电流15A,工作磁场为0.685T时,在35GHz频率放大器可以获得超过250kW的输出功率,大于21dB的增益,23%的效率和约为120MHz的带宽。计算结果为实际工程设计提供了有益的参考。     

140 GHz共焦波导结构回旋行波管放大器

为减少太赫兹回旋器件模式密度和降低模式竞争问题,利用具有模式选择特点的共焦波导结构作为140 GHz回旋行波管(Gyro-TWT)的高频互作用系统。在理论分析基础上,建立注波互作用计算模型并对其进行数值计算;通过对共焦波导高频场分布、衍射损耗、耦合系数以及注波互作用效率等输出参量的分析,选择HE06作为工作模式,确定了140 GHz Gyro-TWT放大器的基本结构和工作参数,并利用注波互作用非线性理论进行分析。模拟结果表明：在注电压为35 kV,注电流2 A,速度比为0.75时,该高频结构在140 GHz频点获得12 kW峰值输出功率,17.1%电子效率和38 dB饱和增益,3 dB带宽达到6 GHz。     

频率可调太赫兹回旋振荡管互作用电路的设计与研究

根据动态核极化核磁共振成像技术对回旋振荡管的要求,设计了130 GHz 回旋振荡管的注波互作用电路,基于线性理论对互作用电路进行了研究并选择了合适的工作点,分析了电路的频率调节特性。利用相对论电子回旋脉塞非线性理论对互作用系统进行了模拟和计算,优化了工作参数,计算了磁场及电子注参数对输出功率及效率的影响。最后,用粒子模拟方法进行了模拟并与非线性理论结果进行了比较,两者符合得很好。模拟结果显示,当电压为10 kV、电流为0.3 A、磁场强度由2.34 T 增加到2.41 T 时,输出功率由1310 W 减小到230 W,对应的效率分别为43.6%和7.7%,振荡管的频率可调范围约为2.7 GHz。     

新型高效率二次谐波宽带可调复合互作用回旋管

该文利用回旋管注-波模式耦合理论,提出了返波振荡-速调群聚-行波放大复合互作用回旋管工作原理。理论分析表明,Ka波段二次谐波连续磁调谐复合互作用回旋管的工作效率高达40%,磁调谐带宽为10%。利用该复合互作用工作原理,回旋管振荡器可实现毫米波电磁辐射源的高效率、高功率输出及宽频带连续磁调谐。     

V波段微带线行波管慢波结构的设计

提出了一种新型的微带线慢波结构。与传统的N型微带线慢波结构相比,新型结构具有相速值较小、工作电压低、功率大、耦合阻抗高等特点。利用HFSS和CST分别对此结构在V波段进行高频特性、传输特性和注-波互作用仿真,得出在60GHz频点耦合阻抗大于20Ω,在55~63GHz频段内VSWR<1.5;当输入功率为100mW时,并且带状电子注的电流和电压分别工作在100mA和5kV的条件下,该行波管慢波结构的最大输出功率为115W,平均互作用效率为14.6%,瞬时3dB带宽为5GHz(56~61GHz)。     

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。     

基于SDRWS的340 GHz返波管的计算机模拟

采用计算机模拟的方法对一种基于双排矩形波导慢波结构(SDRWS)的340 GHz返波管进行详细研究。首先对返波管所需的电子枪和永磁聚焦系统进行计算机模拟,结果表明,永磁聚焦系统与电子枪相结合,能够产生并维持14~17 kV,43.4 mA的电子注和18~21 kV,56.1 mA的电子注,且电子注电压在14~21 kV之间时,电子注在慢波结构区域的最大半径小于0.08 mm,半径波动最大值为0.034 mm。利用所计算的电子注,对基于SDRWS的340 GHz返波管进行互作用计算,结果表明,当电子注电压在14~21 kV之间调谐时,输出电磁波在326~352.6 GHz之间,输出功率大于2 W。同时,SDRWS的电子注通道半径为0.09 mm,相对较大,降低了返波管的制造难度。     

W波段梯形慢波结构返波管的研究

本文采用梯形慢波结构作为返波管的高频系统,研究了一种工作在低电压条件下的W波段返波管。本次研究采用三维电磁仿真软件CST计算梯形慢波结构的色散特性和耦合阻抗;采用PIC软件模拟注波互作用。结果显示:电压范围在5.5~8kV变化时,梯形线工作在104GHz左右,带宽约为1.35GHz。注波互作用仿真结果显示其工作在高次空间谐波处,输出效率在2%左右。     

周期介质加载大轨道回旋行波管研究

通过耦合系数、模式竞争和起振条件分析谐波状态下采用大回旋电子注周期性介质加载结构的注波互作用特点,并通过理论分析和PIC粒子模拟,优化设计出一支Ka波段大回旋电子注回旋行波管。该回旋行波管处于二次谐波工作状态,互作用结构采用周期性介质加载结构,结构简单,工艺成熟。仿真结果表明,在电子注为75 kV、电流为9 A、磁场强度仅为0.51 T的工作条件下,所设计的回旋行波管最大输出功率达到了156 kW,3 dB带宽为4.4 GHz,最大增益为47.18 dB,磁场用常规电磁线圈磁体产生即可达到要求。     

Gyrotron Backward Wave Oscillator Experiments with a Relativistic Electron Beam Using an X-Band Rectangular Waveguide

A mildly relativistic electron beam (500keV, 200A, 10ns) injected into an X-band rectangular waveguide immersed in a uniform axial magnetic field (4-10kG) produced magnetically tunable microwave radiation in the 9-13 GHz frequency range with an estimated output power of 1MW. The frequency range and tunability of the radiated microwave agreed with a theoretical model for a gyrotron backward wave oscillator taking into account the low energy component of the beam electron.     

Dependence of Output Power on Cavity Length in a Gyrotron Backward Wave Oscillator

A relativistic electron beam (500 keV, 200 A, 10 ns) generated magnetically tunable microwave radiation in a frequency range of 9-13 GHz when it is injected into an X-band rectangular waveguide immersed in a uniform axial magnetic field (4-10 kG). The mechanism of the microwave radiation was identified as the gyrotron backward wave interaction. The output power of the radiated microwave increased exponentially with the increase of the cavity length.     

System Development and Performance Testing of a W-Band Gyrotron

A high-power W-band gyrotron has been designed and performance tested in Korea, with an output power in the range of tens of kilowatts. The gyrotron consists of a diode-type electron gun operating at 40 kV, a TE6,2 mode interaction cavity, and a mode converter for producing a highly Gaussian output mode beam. Presented here are the detailed component design procedure and the experimental results of the gyrotron’s performance evaluation. A maximum power of 62 kW was achieved with an efficiency of 22 %, and a highly Gaussian output beam was observed. The gyrotron’s output beam is analyzed, and its transmission through an oversized waveguide is discussed. This gyrotron is the first gyrotron developed in Korea with high power greater than 10 kW and high frequency greater than 90 GHz.     

Further Characterization of 394-GHz Gyrotron FU CW GII with Additional PID Control System for 600-MHz DNP-SSNMR Spectroscopy

A 394-GHz gyrotron, FU CW GII, has been designed at the University of Fukui, Japan, for dynamic nuclear polarization (DNP)-enhanced solid-state nuclear magnetic resonance (SSNMR) experiments at 600-MHz ¹H resonant frequency. After installation at the Institute for Protein Research (IPR), Osaka University, Japan, a PID feedback control system was equipped to regulate the electron gun heater current for stabilization of the electron beam current, which ultimately achieved stabilization of output power when operating in continuous wave (CW) mode. During exploration to further optimize operating conditions, a continuous tuning bandwidth of approximately 1 GHz was observed by varying the operating voltage at a fixed magnetic field. In the frequency range required for positive DNP enhancement, the output power was improved by increasing the magnetic field and the operating voltage from their initial operational settings. In addition, fine tuning of output frequency by varying the cavity cooling water temperature was demonstrated. These operating conditions and ancillary enhancements are expected to contribute to further enhancement of SSNMR signal.     

Continuously Frequency Tunable High Power Sub-THz Radiation Source—Gyrotron FU CW VI for 600 MHz DNP-NMR Spectroscopy

A high frequency gyrotron with a 15 T superconducting magnet named Gyrotron FU CW VI has achieved continuous frequency tuning through the relatively wide range of 1.5 GHz near 400 GHz. The operation is at the fundamental cyclotron resonance of the TE₀₆ cavity mode with many higher order axial modes. The output power measured at the end of the circular waveguide system ranges from 10 to 50 watts at the low acceleration voltage of 12 kV for beam electrons. The beam current is also low. It is around 250 mA. This gyrotron is designed as a demountable radiation source for the 600 MHz DNP-NMR spectroscopy. The design and operation results of the gyrotron FU CW VI are presented.     

Design of a Ka Band 35 kW CW Low-Voltage Harmonic Gyrotron

In this paper, a continuous wave (CW) low-voltage second harmonic gyrotron with the conventional cavity has been preliminarily designed and evaluated with self-consistent nonlinear simulation code and the particle-in-cell code CHIPIC. The simulation results of the two codes are shown to be in agreement basically. The 35 kW CW output power of the designed harmonic gyrotron driven by a 25 kV 5.0A electron beam from a magnetron injection gun (MIG) is obtained. The maximum output power and the electronic efficiency of the gyrotron is about 35 kW and 30% respectively.     

35GHz三次谐波低电压回旋管理论研究

用动力学理论分析了三次谐波复合腔回旋管中的注-波互作用,选取了工作点;建立了突变复合腔回旋管的自洽非线性理论模型,该模型既考虑了电子和高频场的自洽相互作用又考虑了复合腔过渡部分模式的耦合,基于该理论模型,对一只三次谐波35GHz突变结构复合腔回旋管中电子注与H₆₁-H₆₂高频场互作用进行了数值模拟,当电流20A,磁场为0.442T时,互作用效率为24%,输出功率为210kW.     

A Theory of the Orotron with an Inclined Electron Beam

A linear and non-linear theory of the orotron with an electron beam inclined with respect to the surface of a periodic structure is presented. The beam inclination provides the possibility of the effective interaction of all particles of thick electron beam with slow evanescent harmonic of the cavity mode. On the basis of obtained analytical expression for the orotron starting current, the possibility to increase the device frequency up to 600 GHz is discussed. According to numerical simulations, the inclination of the beam allows increasing significantly both the electron efficiency and the output power of the device. The project of low-voltage orotron with the operating frequency of 100 GHz and output power of 10 W is proposed.     

带状电子注驱动的准光谐振腔回旋管

回旋管作为一种重要的真空电子源,能够在毫米波和太赫兹频段生成高峰值以及高平均功率的电磁辐射,在波谱学、雷达、通信、生物医学等领域具有广泛的应用前景。传统的回旋管将不可避免地面对激烈的模式竞争问题,引入准光谐振腔将有望大大减小模式竞争的激烈程度。本文基于电子回旋脉塞理论,将准光谐振腔及带状电子注进行结合,以期实现更高的输出功率及效率。仿真结果表明,在电子电压为40 kV,背景磁场为8.4 T时,设计的准光回旋管能在220 GHz频点处产生6.1 kW的输出,电子效率达到6.1%且在一段时间内能稳定运行。本文结构将可能为高频段乃至高次谐波工作的回旋管设计提供全新方案,从而进一步用于通信、雷达等领域。