电子注偏心对共焦波导回旋行波管的影响

利用线性和非线性理论研究了电子注偏心对0.22 THz回旋行波管注波互作用的影响。基于色散方程研究了电子注偏心对线性增益、绝对不稳定性的起振电流和返波振荡的起振条件的影响。引入自洽非线性理论,分析了电子注偏心对输出功率和注波互作用效率的作用。同时,在考虑速度离散的情况下,研究了电子注质量对共焦波导注波互作用的影响。结果表明,电子注偏心会导致效率的降低。     

损耗介质加载结构Ka波段TE_(01)模回旋行波管放大器稳定性的分析

该文从分析损耗介质加载金属圆波导中电磁波传输特性出发,应用回旋行波管放大器小信号色散方程,研究损耗介质加载结构TE01模回旋行波管放大器绝对不稳定性振荡和回旋返波振荡对器件稳定性的影响.结果表明:损耗介质的加载,可以提高绝对不稳定性起振电流,提高的幅度依赖于工作磁场偏离饱和磁场的程度、电子束横纵速度比等;增加波导损耗介质加载的厚度,可以提高竞争模式的回旋返波起振长度.合理选择波导的损耗层厚度、介电常数以及回旋行波管的工作电压、工作磁场和电子束横纵速度比,可以有效兼顾带宽和抑制不稳定性,保证回旋行波管放大器稳定工作.     

损耗介质加载结构Ka波段TE01模回旋行波管放大器稳定性的分析

该文从分析损耗介质加载金属圆波导中电磁波传输特性出发,应用回旋行波管放大器小信号色散方程,研究损耗介质加载结构TE₀₁模回旋行波管放大器绝对不稳定性振荡和回旋返波振荡对器件稳定性的影响。结果表明：损耗介质的加载,可以提高绝对不稳定性起振电流,提高的幅度依赖于工作磁场偏离饱和磁场的程度、电子束横纵速度比等;增加波导损耗介质加载的厚度,可以提高竞争模式的回旋返波起振长度。合理选择波导的损耗层厚度、介电常数以及回旋行波管的工作电压、工作磁场和电子束横纵速度比,可以有效兼顾带宽和抑制不稳定性,保证回旋行波管放大器稳定工作。     

Ku 波段回旋行波管设计与分析

设计了用于Ku波段的介质加载回旋行波管。阐述了磁控注入电子枪的设计,采用均匀介质加载的结构来抑制回旋行波管的自激振荡,降低了回旋行波管的起振电流,同时提高了寄生模式的起振长度。设计了线极化输入耦合器。设计的回旋行波管工作电压为70kV,工作电流为10A,最大峰值功率210kW,最大功率处增益为35dB,3dB带宽为1.8GHz。     

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。     

回旋行波管分布式介质加载高频结构研究

利用线性理论对Ka波段工作模式为TE01模的回旋行波管进行了稳定性分析,计算了介质加载条件下工作和寄生模式的传播损耗,以及不同传播损耗下工作模式的起振电流;对不同介质加载条件和工作电流,给出了3个主要寄生模式的起振长度;确定了介质加载厚度以及相对介电常数等参数。计算结果表明,在优化得到的介质加载条件下,寄生模式在其各自振荡频点的单位长度传播损耗大于抑制各寄生模式返波振荡所需最低损耗值要求;工作模式起振电流大于设计所需工作电流;寄生模式的起振长度大于设计的介质加载段和未加载段长度;设计的介质加载参数能够满足抑制工作和寄生模式自激振荡的要求。利用优化设计的高频结构及介质加载参数,进行了整管热测实验,得到了输出功率160kW,饱和增益40dB,效率22.8%以及3dB带宽5%的回旋行波管。     

220 GHz周期介质加载波导回旋行波管的理论设计与PIC仿真

通过理论研究和粒子仿真（Particle in Cell , PIC）,设计了一支工作在基波TE01模式下,采用周期性介质加载（PDL）波导的220 GHz回旋行波管（gyrotron traveling wave tube, Gyro-TWT）。通过研究寄生振荡的起振阈值和加载介质环,成功抑制了寄生振荡（绝对不稳定性振荡和返波振荡）。分别采用了非线性理论程序与粒子仿真对注波互作用进行研究,对比了两种结果基本一致。PIC仿真结果显示,优化后的回旋行波管,工作在220 GHz时,在输入70 kV和3 A电子注的情况下,饱和输出功率为55.61 kW,对应的效率为26.48%,饱和增益为53.56 dB,-3 dB带宽为12 GHz。     

3mm二次谐波回旋振荡管设计与数值模拟

二次谐波回旋振荡管的互作用磁场比基波回旋振荡管的磁场降低了一半,从而降低了设计难度,具有广阔的应用前景。通过对单腔结构的W波段二次谐波回旋振荡管高频结构、起振电流、模式竞争以及注波互作用研究,确定了W波段TE02模二次谐波回旋振荡管的基本工作参数,通过粒子模拟(PIC)软件进行计算,在电子注电压为60kV,注电流为6A及速度比为1.5时,获得了67.5kW的输出功率和超过18%的效率,且工作稳定。     

W 波段回旋行波管高频结构设计和仿真*

对W 波段回旋行波管的高频结构的设计参数进行了分析计算与软件仿真,通过色散关系确定了磁场 取值,通过对返波振荡的分析确定了高频结构———周期衰减材料加载,通过对绝对不稳定性振荡的分析确定了工作 电流和横纵速度比的取值范围,最终得到了W 波段回旋行波管的工作参数。采用粒子模拟软件进行模拟计算,可以 得到155kW 的峰值功率输出和5.5GHz 的带宽,并给出了输出功率与回旋行波管各工作参数之间的关系曲线,进一 步证明了对返波振荡和绝对不稳定性振荡的分析与参数选取的合理性。实际加工的回旋行波管在测试中峰值功率 大于100kW,增益大于40dB,效率大于12%,3dB 带宽为4.1GHz。     

TE11回旋返波振荡的起振分析

回旋行波管微波放大器具有高功率,宽带宽的特点。但是其极易受到寄生模式的干扰,返波振荡就是制约回旋行波管性能的主要因素之一。这里基于回旋行波放大器线性理论,着重研究了在回旋行波管TE01工作模式下TE11模的起振频率和起振长度,以及分布损耗对返波起振的影响。分析结果对回旋行波管放大器以及回旋返波管振荡器的工程设计提供了一定的参考。     

Stability analysis of TE01 gyrotron travelling wave amplifiers

The fundamental harmonic TE₀₁ gyrotron travelling wave amplifier (gyro-TWT) is a high-power, broadband, millimetre-wave amplifier with a low ohmic dissipation and a large guiding centre radius. However, spurious oscillations may reduce the amplification of the gyro-TWT. The stability of severed and distributed-loss gyro-TWTs is analysed, using a self-consistent simulation code. A nonlinear analysis of typical oscillations, including absolute instability, gyrotron backward oscillation (gyro-BWO) and reflective oscillation, is presented. Simulation results indicate that attenuating severs in the severed gyro-TWT do not suppress spurious oscillations, and that increasing the wall losses to suppress gyro-BWO in the distributed-loss gyro-TWT degrades the efficiency of the gyro-TWT amplifier. A multi-stage distributed-loss gyro-TWT design is developed to stabilize the amplification. The lossy and severed sections of the multi-stage gyro-TWT seem to increase effectively the start-oscillation currents of absolute instability and gyro-BWO, respectively. The multi-stage gyro-TWT is predicted to yield a peak output power of 155?kW at 32.9?GHz with an efficiency of 15%, a saturated gain of 45?dB and a bandwidth of 2.2?GHz for a 100?kV, 10?A electron beam with an axial velocity spread Δv_z /v_z = 5%.     

W-Band Second-Harmonic Gyrotron Traveling Wave Amplifier with Distributed-Loss and Severed Structures

The second harmonic TE₀₂ gyrotron traveling wave amplifier (gyro-TWT) is a high-power, broadband, millimeter-wave amplifier with a low applied magnetic field. Mode-selective interaction circuits were applied to suppressing spurious oscillations. However, the mode-selective interaction circuit may perturb the operating mode in the gyro-TWT. A multi-stage gyro-TWT design with distributed-loss and severed structures is proposed to stabilize the amplification. This study presents a nonlinear analysis of typical oscillations, including absolute instability, gyrotron backward oscillation (gyro-BWO) and reflective oscillation. The lossy and severed sections of the multi-stage gyro-TWT seem to increase effectively the start-oscillation currents of the absolute instability, gyro-BWO, and reflection oscillation. The multi-stage gyro-TWT is predicted to yield a peak output power of 215 kW at 89.9 GHz with an efficiency of 14.3 %, a saturated gain of 60 dB and a bandwidth of 1.7 GHz for a 100 kV, 15 A electron beam with an axial velocity spread Δν _z/ν _z = 5%.     

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.     

Design and Simulation of an Ultra-Broadband Ku-BandGyro-TWT for Radar Applications

In this paper, the design of an ultra-broadband Ku-band gyro-TWT amplifier is presented in detail. The preliminary parameters of the interaction structure derived from the dispersion relationship and the linear theory of the gyro-TWT with distributed wall losses is optimized by the self-consistent nonlinear code. The performance of the designed gyro-TWT is simulated by the nonlinear code. The simulation results show that the gain and the bandwidth of the designed Ku-band gyro-TWT is about 36.5 dB and 2.1 GHz with 3 dB bandwidth (about 12.7%) respectively at the input power 19.0 W.     

Self-consistent Nonlinear Analysis and 3D Particle-In-Cell Simulation of a W-band Gyro-TWT

The self-consistent nonlinear analysis and CST 3D particle-in-cell (PIC) simulation of a W-band gyrotron traveling wave tube (gyro-TWT) are presented in this paper. Both the simulation results of the two codes are excellent agreement with each other. The gyro-TWT loaded with periodic lossy dielectric in the circuit for suppressing potential spurious oscillations. It is driven by a 70kV, 10A gyrating electron beam with velocity ratio of 1.0. PIC simulation results are: the maximum peak output power of 198kW, statured gain of 62.3dB and efficiency of 28.3% at 92.5GHz. Only the operating mode TE ₀₁ is observed in the CST 3D simulation and the potential competing backward wave oscillations are effectively suppressed. The CST simulation also predicts that the device works stably under the condition of the beam current lower than 14A and B ₀ /B _g lower than 1.05. The simulated bandwidth with peak power greater than 100kW is 6.8GHz without axial velocity spread, and 4.1GHz with 6% axial velocity spread.     

高功率毫米波回旋器件实验研究

介质加载是解决回旋行波管振荡一个较好的方法,本文利用这种结构在Ka波段回旋行波管的实验中利用这种结构在工作模式TE01,加速电压66 kV,电子注电流13A得到了293 kW的峰值输出功率,最大增益56 dB,效率34.2％,3 dB带宽2.1 GHz的结果;介绍了W波段回旋行波管、回旋振荡管、Q波段回旋行波管的实验情况.     

A Stable 0.2-THz Coaxial-Waveguide Gyrotron Traveling-Wave-Tube Amplifier with Distributed Losses

For high-power operation, a THz gyrotron traveling-wave-tube (gyro-TWT) amplifier must operate in a high-order waveguide mode to enlarge the transverse dimension of an interaction waveguide. However, a gyro-TWT amplifier operating in a high-order waveguide mode is susceptible to spurious oscillations. To improve the device stability, in this study, we investigate the possibility of using a coaxial waveguide with distributed losses as the interaction structure. For the same required attenuation, all threatening oscillating modes can be suppressed using different combinations of losses of inner and outer cylinders. This provides flexibility in designing distributed losses when considering the ohmic loading of the interaction structure. We predict that the 0.2-THz gyro-TWT can stably produce a peak power of 14 kW with an efficiency of 23 %, a 3-dB bandwidth of 3.5 GHz, and a saturated gain of 50 dB for a 20-kV 3-A electron beam with a 5 % velocity spread and 1.0 velocity ratio.     

Gyrotron-traveling wave-tube circuits based on lossy ceramics

The gyro-traveling wave tube (gyro-TWT) is a microwave amplifier with simultaneous high power, high frequency, and broad bandwidth capabilities. Techniques for providing a controlled loading of the TE/sub 01/ cylindrical-guide operating mode of a 35 GHz gyro-TWT using monolithic, lossy ceramic structures are presented. The loading scheme, which also suppresses spurious backward-wave oscillations in the TE/sub 11/, TE/sub 21/, and TE/sub 02/ modes, is based on a sequence of alternating ceramic cylindrical shells and metal rings to form the electron beam tunnel. Design techniques for achieving optimal performance and methods for reducing the sensitivity to temperature-induced variations in ceramic dielectric properties are presented.     

A Lossy Dielectric-Ring Loaded Waveguide With Suppressed Periodicity for Gyro-TWTs Applications

A dielectric-loaded (DL) waveguide is an attractive possibility for interaction circuits with high-power sources in the millimeter-wave regime down to tenths of millimeters, particularly for gyrotron-traveling-wave-tube amplifiers (gyro-TWTs). We present results on a systematic investigation of the influence of the periodically loaded lossy dielectric on the propagation characteristics of the operating modes, which reveals that a complex mode in the periodic system can be mapped to a corresponding mode in an empty waveguide or a uniform DL waveguide. Dielectric losses not only induce modal transitions between different modes with similar field structures and close phase velocities in the uniform system but also unify the discrete mode spectrum into a continuous spectrum in the periodic system. Since the lossy dielectric functions as a power sink, the higher order Bloch harmonic components arising from the structural periodicity are suppressed, and the mode spectrum of the lossy periodic system degenerates into that of an empty waveguide. This alleviates the potential danger of spurious oscillations induced by the higher order harmonic components, making the periodic lossy DL waveguide promising in a high-power millimeter-wave gyro-TWT.