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。     

Ka波段二次谐波回旋速调管放大器的研究

应用自行编制的电子注-波互作用的自洽非线性模拟程序,我们对Ka波段二次谐波回旋速调管放大器的注-波互作用进行了研究.通过对回旋速调管放大器的数值模拟,我们详细描述了二次谐波电子注-波互作用过程中电子群聚的物理图景;并研究了不同变化参数(漂移管长度和静磁场强度)对电子效率的影响.模拟结果表明:设计的二次谐波回旋速调管放大器的电子效率为15.4%,相应的输出功率约为161kW.     

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。     

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。     

W波段回旋行波管放大器速度零散的分析

通过包含速度零散影响的回旋行波管放大器的非线性理论模型,以W波段两段结构回旋行波管放大器为例,详细分析了速度零散对放大器电子注—波互作用的影响.模拟结果表明,通过合理地调整互作用长度,减小电子横纵速度比、调节工作磁场等方法可以有效地减小速度零散的影响,对回旋行波管放大器的优化设计提供了理论依据.     

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。     

光电子技术

0513334Ka 波段二次谐波回旋速调管放大器的输出特性[刊,中]/梁显锋//强激光与粒子束.—2005,17(1).—113-116(E)根据谐波回旋速调管放大器的注-波互作用特点,对 Ka 波段二次谐波三腔回旋速调管放大器的输出腔进行了数值模拟和优化设计,获得了输出腔末端高频波绕射输出孔径和腔体绕射 Q 值的对应关系。通过PIC 粒子模拟,分析了该放大器的频率响应特点等输出特性。结果表明,在35GHz 频率,磁场0.685T,电子注电压70kV,电流15A,横纵速度比为1.45,输入功率1.6kW 时,放大器可以获得超过220kW 的峰值输出功率、约22%的效率和23dB 的增益,3dB 带宽可以达到110MHz。参9     

Ka波段基波回旋行波管放大器的模拟与设计

完成了Ka波段基次谐波TE01模回旋行波管的初步设计,通过PIC模拟计算获得了回旋行波管稳定工作的详细物理图像和参数依赖关系．模拟计算表明,在电子注电压为100kV,电子注电流为20A,工作磁场为1．27T时,放大器可以获得大于450kW的输出功率、50dB增益、大于22．5％的效率和约为5％的带宽．     

Ka波段谐波倍增回旋行波管绝对不稳定性分析

为了保证Ka波段谐波倍增回旋行波管放大器稳定的工作。在回旋行波管线性理论的基础上,用自编程序数值求解其小信号色散方程,得到不同工作电流下方程的根随归一化频率变化的关系图,结合工作模式绝对不稳定性发生的条件,得到了不同条件下Ka波段谐波倍增回旋行渡放大器基波段TE01,模绝对不稳定性的起振电流,并给出了其产生的物理解释。通过分析讨论绝对不稳定性的起振电流随电子注横纵速度比和引导磁场的变化关系。最终从理论上确定了保证放大器稳定工作的电流大小为10A。     

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。     

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%.     

Marginal stability design criterion for gyro-TWTs and comparison of fundamental with second harmonic operation

Stability properties of both the fundamental and second harmonic gyrotron travelling wave amplifier (gyro-TWT) are examined with multi-mode particle simulations. The second harmonic cyclotron interaction with an axis-encircling electron beam is found to be more stable to oscillations and can yield significantly greater power than the fundamental harmonic gyro-TWT. A multiple stage interaction structure based on a marginal stability criterion is proposed and illustrated with examples of a 128kW fundamental gyro-TWT and a 532 kW second harmonic gyro-TWT, Stable amplification at much higher power levels is in principle possible.     

周期损耗介质加载波导与均匀圆波导间的模式映射

损耗介质环与金属环间隔加载的周期损耗介质波导能够有效地控制各种模式的衰减特性,这对于抑制毫米波回旋行波管放大器的绝对不稳定性和提高其性能具有重要作用.针对应用于Ka波段、TE01模的回旋行波管放大器的周期损耗介质加载圆波导,系统地分析了该周期系统与均匀系统间的模式映射关系.研究表明,当介质层厚度一定时,均匀介质加载波导中的高阶模式可以映射为光滑波导中的低阶模式,且相互映射的模式在中空区域的场型一致.周期系统中的模式表现出复合模式的分布.在一个周期中,介质段和金属段的模式分别映射为均匀介质波导和金属波导中的模式.明确周期介质加载波导系统与均匀波导系统间的模式映射关系是分析发生在这种复杂的互作用回路中的回旋电子脉塞注波互作用的前提,对简化其物理模型具有指导作用.     

Experimental investigation of a broadband dielectric-loadedgyro-TWT amplifier

The bandwidth of a gyrotron travelling wave amplifier has been broadened by incorporating a dielectric-loaded interaction waveguide to reduce the circuit's dispersion. This proof-of-principle experiment was designed for the X-band frequency range and operates in the fundamental mode of a rectangular waveguide loaded with dielectric Macor. The amplifier is zero-drive stable and demonstrates a peak output power of 55 kW, 11% efficiency, 27 dB saturated gain with an unprecedented untapered gyro-TWT constant-drive bandwidth of 11% and a saturated bandwidth of 14%. Its performance can be further enhanced by reducing the beam's axial velocity spread as shown by previous simulation studies     

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.     

Optimization of Vane-Parameters for Gain-Frequency Response of Vane-Loaded Gyro-TWT

This paper discusses an analytical method to study the effects of the vane-parameters on the gain-frequency response of an azimuthally periodic vane-loaded cylindrical waveguide interaction structure for the gyro-traveling wave tube (gyro-TWT) amplifier in the small-orbit TE₀₁ waveguide mode configuration. The vane-loaded gyro-TWT enables the higher gain than that of the smooth-wall device. An optimum choice of the vane dimensions causes a change in the frequency corresponding to the peak-gain.     

GAIN AND BANDWIDTH ANALYSIS OF A VANE-LOADED GYRO-TWT

Theoretical investigation of the peak-gain and 3-dB bandwidth of the vane-loaded gyro-traveling wave tube (gyro-TWT) amplifier in the small-orbit TE₀₁ waveguide mode configuration at 35 GHz has been presented. The vane-loaded gyro-TWT enjoys higher gain and bandwidth compared to that of the smooth-wall device. In the analysis, the azimuthal harmonic effects generated due to the angular periodicity of vanes in the wedge-shaped metal vane-loaded cylindrical waveguide interaction structure have been taken into account in the cold (beam-absent) dispersion relation only.     

Theoretical and Experimental Investigation of a Ka-band Gyro-TWT with Lossy Interaction Structure

The stability analysis of a Ka-band gyrotron traveling-wave tube amplifier (gyro-TWT) operating in the circular TE₀₁ mode at the fundamental cyclotron harmonic is presented. The small signal linear theory is used to analyze the amplification of operation mode and oscillation of parasitic modes. The optimum dielectric parameters including loss layer thickness and permittivity are given. Propagation loss of operation mode is 3 dB/cm with the thickness of loss layer d = 0.7 mm and relative permittivity ξ″ = 11−6j, and propagation loss per unit length of parasitic modes TE₁₁, TE₂₁, TE₀₂ at each oscillation frequency (24.85 GHz, 27.85 GHz, 61.2 GHz) is 2.5 dB/cm, 6 dB/cm, 7.5 dB/cm, respectively, sufficient to suppress oscillations of operation and parasitic modes. Taking advantage of the optimized parameters of loaded dielectric, a high gain scheme has been demonstrated in a 34-GHz, TE₀₁-mode gyro-TWT, producing 160 kW saturated output power at 40 dB stable gain and 22.8% efficiency with a 3-dB bandwidth of 5%.     

Design and Simulation of a Ka-Band TE<Subscript>11</Subscript> Mode Gyro-Traveling-Wave Amplifier

The design of a Ka-band gyrotron traveling wave amplifier with high power and wide bandwidth is presented in detail. The amplifier operates in the TE11 circular mode at the fundamental cyclotron harmonic. The distributed loss technique is adopted in the interaction circuit which guarantees the amplifier zero-drive stability. The effects of the parameters such as input power, driver frequency and magnetic field on the performance of the gyro-TWT are discussed. The simulation results show that the gain and the 3dB bandwidth of the designed Ka-band gyro-TWT are about 56.0dB and 1.8 GHz ,respectively. The peak output power and the corresponding electronic efficiency are about 100 kW and 23.8% respectively with the voltage 70 kV and the current 6A at the velocity ratio 1.0.