Ka波段二次谐波回旋速调管放大器的输出特性

 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35 GHz频率,磁场0.685 T,电子注电压70 kV,电流15 A,横纵速度比为1.45,输入功率1.6 kW时,放大器可以获得超过220 kW的峰值输出功率、约22%的效率和23 dB的增益,3 dB带宽可达到110 MHz。     

Study of high-power Ka-band second-harmonic gyroklystron amplifier

The self-consistent nonlinear theory of two-cavity high-harmonic gyroklystron amplifier has been developed. The efficiency and gain of a second-harmonic gyroklystron were calculated numerically. The results obtained were used to choose the optimal parameters of the experimental second-harmonic tube. The experimental study was carried out to test high-harmonic amplifier concept. Two-cavity 35 GHz second harmonic gyroklystron with the TE₀₂₁ cavity mode has been designed and tested in pulse operation. Output power of about 260 kW with efficiency 18% and 17 dB gain have been produced at 72 kV beam voltage and 20 A beam current. Bandwidth of about 0.1% has been observed. The restriction of the output power, efficiency, and gain was caused by spurious oscillations excited in the second cavity in the TE₀₁₁ mode at the fundamental cyclotron frequency     

Kα波段TE01模基波回旋速调放大器的设计与实验

在回旋速调放大器自洽非线性大信号理论分析和数值计算的基础上,给出了一支Kα波段TE₀₁模4腔基波回旋速调放大器的设计方案,并完成了样管的研制.同时对样管进行了热测实验,得到了如下实验结果:注电压为70 kV,电流为10 A,输入功率为60 W,磁场强度1.31 T,中心频率34 GHz,峰值功率245 kW,平均功率大于3 kW,增益36.1 dB,效率 35%,3 dB带宽大于280 MHz. 关键词： 回旋速调放大器 注-波互作用 群聚腔 输入腔     

Ka波段二次谐波回旋速调管放大器输入耦合器的分析与模拟

 对应用于Ka波段二次谐波回旋速调管放大器的一种输入耦合器进行了分析，并利用三维电磁模拟软件HFSS和ISFEL3D对其进行了模拟与设计。研究结果表明，该输入耦合器具有较高的能量耦合效率，并能在Ka波段获得高纯度的TE₀₂₁谐振模式。     

Present status of a 17.1-GHz four-cavity frequency-doubling coaxialgyroklystron design

A design of a Ku-band 17.1-GHz four-cavity coaxial gyroklystron amplifier for driving future linear colliders is presented. The X-band input cavity operates in the TE_0.11 mode, whereas the remaining three cavities (buncher, penultimate, and output) operate in the TE₀₂₁ mode, doubling the frequency of the input signal. The electron beam parameters are the following: current of 540 A, voltage of 460 kV, perpendicular-to-parallel velocity ratio of 1.5, and a parallel velocity spread of 6.4%. The output cavity has been simulated as (1) zero-drive unstable with Q-factor of 320 and (2) zero-drive stable with Q-factor of 250. The simulations show that the maximum efficiency in the first case is 37.4%, and in the second one is 34.4%. In both cases, a high gain of 60 dB at a 100-MW output power level can be realized     

100-150 MW designs of two- and three-cavity gyroklystron amplifiersoperating at the fundamental and second harmonics in X- andKu-bands

Efficient 100-150 MW X- and Ku-band microwave sources with pulselengths of 1 μs are being developed for driving future linear colliders. Two- and three-cavity co-axial designs of relativistic gyroklystron amplifiers are presented here which fulfill these requirements. Numerical simulations predict over 40% efficiency, 45-50 dB gain, and 100-160 MW power level for the gyroklystron designs operating at fundamental (8.568 GHz) and second harmonic (17.136 GHz). It is shown that introducing a penultimate (buncher) cavity significantly improves efficiency and gain of the second-harmonic amplifier     

High-power X-band amplification from an overmodedthree-cavity gyroklystron with a tunable penultimate cavity

Experimental results for a 10 GHz TE₀₁ mode three-cavity gyroklystron with a tunable penultimate cavity are presented. The electron beam was produced by a pulse line modulator and a magnetron injection gun which operates to 433 kV and 225 A with 1 μs flat-top. Three-cavity circuits have produced a peak power of 27 MW with efficiency of 32% and pulse energy of 39 J. A maximum gain of 50 dB was achieved at a peak power of 20 MW, and a maximum efficiency of 37% was achieved at a peak power of 16 MW     

A High-Gain, 28GHz, 200kW Gyroklystron Amplifier

A design study of a high efficiency/gain gyroklystron amplifier is performed to demonstrate amplified radiation power of 200kW operating at 28GHz. A key design feature of the present gyroklystron amplifier is that the amplifier is designed to be high gain so that it can be saturated by a low power solid state power amplifier. A non-linear, time-dependent, large signal numerical code is used to predict tube performance. Simulations predict that a stable amplifier radiation power of 214kW is produced with a saturated gain of 54dB, an electronic efficiency of 37%, and a frequency bandwidth of 0.3% from a five-cavity gyroklystron amplifier. The amplifier gain is found to be very sensitive to a beam velocity spread.     

回旋速调管放大器注-波互作用分析

 给出了自洽非线性大信号理论分析方法,在理论分析和高频计算的基础上,建立了回旋速调管放大器注-波互作用计算模型,对其进行数值计算。研究多种参量对放大器输出功率、增益、效率等的影响,通过优化得到了中心频率34 GHz的四腔回旋速调管放大器设计方案。粒子模拟表明：在工作电压65 kV,注电流8 A,电子注横向与纵向速度比为1.5时,输出功率230 kW,带宽230 MHz,电子效率45%,饱和增益33 dB。     

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.     

8 mm二次谐波回旋速调管谐振腔设计研究

 结合回旋速调管研究的相关理论,考虑到高次谐波工作时带来的模式竞争,以及注-波互作用的耦合关系,讨论了在半径、腔长、杂模抑制以及腔内媒质涂层的介电参量等诸多因数影响的情况下,如何设计二次谐波回旋速调管谐振腔的问题。结合设计方法建模,优化设计出了5个适于8 mm二次谐波工作的谐振腔,通过漂移段连接成两种高频结构,其中一种结构在注-波互作用非线性模拟中取得了251 kW的输出功率,电子效率 23.9%,增益 27.2 dB,3 dB带宽大于0.4%;另一种结构初步取得了246 kW的输出功率,其它参数正在测试之中。     

An Iron-Free Magnetron-Injection-Gun for a 28GHz, 200kW Gyroklystron Amplifier

A design study of a double-anode magnetron-injection-gun is performed to incorporate the electron gun into a high power 28GHz gyroklystron amplifier operating at 70kV and 8.2A. The electron gun is designed to be used in a tapered magnetic field in the cathode region produced from an iron-free superconducting magnet. An electron trajectory code predicts a beam axial velocity spread of 5.9% at = 1.5, 70kV, 8.2A and 10.4kG, which is a high quality electron beam suitable for the high gain, high efficiency, five-cavity gyroklystron amplifier. The successful design of the high quality electron gun is attributed to a longer gap between the modulating anode and the grounded anode compared with the case of the first 28GHz electron gun built with an iron enclosed electromagnet.     

Preliminary Design of a Ka-Band Second Harmonic Gyroklystron Amplifier

The preliminary design of a Ka-band, second harmonic, three cavities gyroklystron amplifier is presented. The beam-wave interaction in the second harmonic gyroklystron amplifier is studied by using a particle-in-cell code, and the validity of the design of the microwave circuit is also discussed. The results show that this gyroklystron can produce an output peak power of over 200kW with 20dB gain and 20% maximum efficiency at 35GHz.     

曙光一号自由电子激光器的理论计算

系统总结曙光一号自由电子激光器理论计算的主要结果:包括曙光一号装置主要参数的选取和理解;磁场失谐曲线的计算;常参数摇摆器和变参数摇摆器的主要结果;高阶波导模的贡献;电子束参数扰动对激光性能的影响;空间电荷效应等。计算结果表明,常参数摇摆器激光输出功率可达80MW,效率约50％;变参数摇摆器激光输出功率可达250MW左右,效率约16％。     

Calculation of the Electron Efficiency for a Two-Cavity Gyroklystron Amplifier by Using a Self-Consistent Code

The beam-wave interaction in a Ka-band, two-cavity fundamental gyroklystron amplifier is studied by using a self-consistent nonlinear simulation code. The electron efficiency for this gyroklystron amplifier is calculated, and the effect of various parameters, such as beam voltage, beam current, electron guiding center radius, velocity pitch ratio and drift tube length on the electron efficiency is discussed in detail.     

S波段多注相对论速调管放大器的数值模拟

利用3维电磁场与粒子模拟软件对S波段多注相对论速调管放大器进行了分析设计和模拟计算。通过对谐振腔本征模的计算确定腔体的冷腔高频特性,采用3维的粒子模拟软件（PIC）模拟分析速调管各腔及整管的束波互作用过程。模拟结果表明:通过引入同轴谐振腔结构,使电子注不必集中在谐振腔中心通过,降低了电场不均性对束波互作用的不利影响;通过引入多电子注,电子在相对较低的轴向聚焦磁场下依然拥有较高的通过率,降低了速调管对聚焦磁场的要求。模拟中采用3个同轴谐振腔进行束波互作用,在输入电压700 kV、束流5.8 kA和聚焦磁场0.4 T的情况下,得到了功率1.4 GW的输出微波,效率为35%。     

Broadband operation of a Ka-band tapered gyro-traveling waveamplifier

A wideband low-voltage millimeter-wave gyro-traveling wave tube (gyro-TWT) amplifier operating in the TE₁₀ rectangular waveguide mode at the fundamental cyclotron frequency is under investigation, The device incorporates precise axial tapering of both the magnetic field and the interaction circuit for broadband operation. Experimental results of a wide (33%) instantaneous bandwidth with a small signal gain in excess of 20 dB and saturated efficiency of ~10% were achieved and shown to be in good agreement with the theory. Reflective instability due to multi-pass effects by mismatches was observed and characterized. Gain and efficiency have been limited by this reflective instability rather than by absolute instabilities which limit the performance of gyro-TWT's with uniform cross-section. The start-oscillation current in terms of the relevant experimental parameters such as the beam velocity ratio (α), magnetic field detuning and reflection coefficient has been measured and compared with theory. Measurements of the phase variation in terms of the RF frequency have shown that the phase varies ±30° from fitted linear phase line     

Design of a high-efficiency low-voltage axially modulatedcusp-injected second-harmonic X-band gyrotron amplifier

We present the theoretical design of a second-harmonic small-orbit gyrotron amplifier which utilizes the interactions between a 35-kV 4-A beam and a TE₀₁₁ cavity to produce over 70 kW of amplified power at 9.9 GHz in a 1.83-kG magnetic field. One of the novel features of this device is that the electron gun produces an axially streaming annular beam which is velocity modulated by a short TM_0n0 input cavity. Perpendicular energy is imparted to the beam via a nonadiabatic magnetic transition at the end of a 13-cm drift region. An electronic efficiency of 53% is predicted with a large signal gain near 20 dB by a single particle code which takes into account nonideal effects associated with finite beam thickness and finite magnetic field transition widths     

谐波回旋速调管的效率优化

推导出了由两个无量纲量群聚系数与相位系数构成的非线性运动方程,并对其进行了数值计算分析。数值计算结果表明:通过优化设计参数,当谐波回旋速调管工作在放大区时,其基波、二次谐波、三次谐波、四次谐波的纵向互作用效率分别可达到55%,40%,30%,15%;当其工作在振荡区时,其基波、二次谐波、三次谐波、四次谐波的纵向互作用效率最高分别可达到93.9%, 88.2%, 81.8%, 62.7%。