Study of a 35-GHz third-harmonic low-voltage complex cavitygyrotron

A self consistent nonlinear theoretical model for a complex cavity gyrotron with abrupt transitions is presented in this paper. The model accounts for mode conversion in the transition region of the complex cavity through the general theory of modal expansion techniques. The interaction between the electron beam and TE₆₁/TE₆₂ RF field in the step cavity for a third-harmonic gyrotron is simulated; many calculations are carried out under different electron beam parameters     

Third-harmonic complex cavity gyrotron self-consistent nonlinearanalysis

Starting from general transmission line equations with an electron beam source, a self-consistent nonlinear theoretical model for a complex cavity gyrotron with gradual transitions is presented in this paper. The model accounts for mode coupling in the transition region of the complex cavity. The interaction between the electron beam and H₆₁-H ₆₂ RF field in the complex cavity for a third-harmonic gyrotron is simulated; many calculations are carried out under different cavity dimensions and electron beam parameters     

35-GHz 25-kW CW low-voltage third-harmonic gyrotron

A 50-kV third-harmonic gyrotron is shown to be capable of high efficiency. Operation at the third harmonic allows the required magnetic field for 35 GHz generation to be supplied by a 4.5-kG permanent magnet. Two gyrotrons employing sliced circuits for mode control have been evaluated with a large-signal nonself-consistent particle-tracing simulation code and found to be capable of producing 25 kW continuously. The preliminary design of a third-harmonic TE₄₁ gyrotron utilizing a magnetron injection electron gun is predicted to yield a device efficiency of 17%, which can potentially be increased to 46% with an ideal single-stage depressed collector, while an axis-encircling electron beam from a Cusp electron gun is predicted to drive a third-harmonic TE₃₁ gyrotron with a device efficiency of 23%, which can theoretically be increased to 45% through the use of an ideal depressed collector     

8mm波段三次谐波复合腔回旋管的非线性分析

利用含电流的传输线方程,在考虑了诸多实际因素影响的情况下,对三次谐波渐变复合腔回旋管进行了自洽非线性模拟,计算了H₅₁₁-H₅₂₁模式下三次谐波多模注波互作用,分析了电子注的厚度、速度零散、速度比α值及磁场波动对多模注波互作用的影响 关键词： 回旋管 复合腔 多模注波互作用 速度零散 速度比α     

渐变复合腔回旋管高次谐波注-波互作用非线性模拟

利用含电流的传输线方程,在考虑多模与电子注互作用及多模耦合的情况下,对三次谐波渐 变复合腔回旋管进行了非线性模拟,计算了H₅₁-H₅₂模式下三次谐 波注波互作用,分析了多模对注-波互作用的影响. 关键词： 回旋管 渐变复合腔 多模注-波互作用 模式耦合 高次谐波     

W波段三次谐波回旋管腔体设计

采用冷腔分析研究了带有光阑结构的开放式谐振腔中的模式竞争,设计了采用TE61模式工作的W波段三次谐波回旋管谐振腔。PIC粒子模拟结果表明:在不考虑腔壁损耗及电子注能散的情况下,采用注电压45 kV、电流3 A的电子注,可以实现三次谐波单模稳定工作,并获得约20 kW的输出功率,对应工作效率14.8%。     

Particle Simulation of a 35-GHz Third-Harmonic Low-Voltage Complex Cavity Gyrotron

A self-consistent particle simulation code has been developed for the research of a 35-GHz third-harmonic Low-voltage complex cavity gyrotron. Aided with microcomputer we use FORTRAN to simulate the process of interaction between electron beam and electromagnetic field. About 7000 macro particles are included at the same time. In the program many useful physical graphs are accessible for the further research of this kind of gyrotron such as the field profile, electrons distribution in various spaces, output power, efficiency and et al. Such simulation results may be helpful to the optimization of devices operation parameters     

Simulation of a High Harmonic Gyrotron with Axis-Encircling Electron Beam and Permanent Magnet

A computer code for simulation of beam-field interaction in a resonant cavity of a gyrotron has been developed. It is based on a self-consistent, time-independent, single-mode physical model. The code has been applied to the analysis of the electrodynamical system of a novel high-harmonic gyrotron with axis-encircling beam and a permanent magnet. In this paper both the physical model and numerical techniques used are outlined. Some results of the numerical experiments are presented and discussed.     

94GHz基波复合腔回旋管数值模拟

通过对94 GHz基波复合腔回旋管中谐振腔结构、电子注参数以及注-波互作用过程的模拟计算研究,分析了复合腔回旋管的高频结构特性和工作参数优化问题.给出了基波H61 -H62模式对复合腔回旋管的模拟设计结果.数值模拟结果表明:在电子注电压40 kV、电流5A、电子横纵速度比1.3、工作磁场3.6T时,回旋管可获得78 k...     

Computer Simulation of Axis-Encircling Beams Generated by an Electron Gun with a Permanent Magnet System

Results from computer aided design of a novel electron gun generating axis-encircling beams are presented and discussed. Numerical experiments were performed by the new version of the software package GUN-MIG named GUN-MIG/CUSP. It is based on a self-consistent relativistic model and is developed as a problem oriented tool for analysis of electron-optical systems with magnetron injection guns (MIG) and electron guns with field reversal (cusp guns), forming axis-encircling beams. As a result of the simulations an electron-optical design of a novel electron gun with permanent magnet system was accomplished. The gun is expected to form high quality beams with small velocity spread and beam ripple. Parameters of the generated beams are appropriate for a prospective weakly relativistic high harmonic large orbit gyrotron (LOG). The development of such device is in progress now at the Research Center for Development of Far-Infrared Region (FIR Center) at Fukui University.     

Special complex open-cavity and low-magnetic-field high-powergyrotron

A theory is proposed for the special complex cavity; it is in the form of a single resonant circuit having a TE_0n&lrarr2;TE_0,n+p mode converter and it features excellent mode selectivity, high power capability, and an asymmetric triangle profile of the RF field that is favourable to efficient operation for a 35-GHz second-harmonic gyromonotron employing this complex cavity with TE₀₃ mode output are numerically illustrated and experimentally demonstrated. Power as high as 200 kW and efficiency as high as 30% have been obtained. These experimental results are record values for a gyrotron operating at the second-harmonic millimeter wavelength. Implications of the single-resonant complex cavity for the fundamental harmonic and third-harmonic high-average-power gyrotron design are discussed     

94-GHz 25-kW CW low-voltage harmonic gyrotron

A low-voltage second-harmonic gyrotron intended as a compact lightweight source has been designed and evaluated with a particle-tracing code and the particle-in-cell code MAGIC. The two codes are shown to be in good agreement when applied to a conventional fundamental-frequency gyrotron and also to the novel second-harmonic gyrotron. The 25-kW continuous wave (CW) 94-GHz gyrotron with a predicted conversion efficiency of 32% and device efficiency of 22.5% is driven by a 25-kV 4.5-A (υ_⊥/υ₂=1.5, Δυ_z/υ_z=7%) electron beam from a magnetron injection gun and employs a low-loss TE₀₂₁/TE₀₃₁ complex cavity for mode control. Although the 17-kG CW gyrotron will use a cryogen-free high-T_c superconducting magnet, a 94-GHz prototype will be tested at low duty with a conventional low-T_c superconducting magnet     

220 GHz回旋管脉冲磁场系统和电子枪的设计与实验研究

 根据220 GHz回旋管的工作要求,设计了其所需的脉冲磁场系统与电子枪。脉冲磁场系统采用哑铃状结构,具有均匀区长、电阻小与电感小等优点,可以在较低电容与电压下获得更高的脉冲峰值磁场,并分析了其脉冲放电特性。电子枪采用双阳极磁控注入枪,用EGUN对其进行了设计优化,电子注纵横速度比为1.53,速度零散为3.1%。实验研究表明,脉冲磁场峰值强度达到8 T,电子注电流达到2 A,电子电流基本传输到靶片,控制极与阳极没有截获到电子,脉冲磁场系统与电子枪工作正常,达到设计要求。     

W波段二次谐波突变复合腔回旋管数值模拟

 通过对二次谐波低电压突变结构复合腔回旋管中谐振腔结构、模式竞争以及电子注-波互作用的研究,分析了高频结构特性、寄生模式的抑制和工作参数优化等问题。给出了3 mm 二次谐波低损耗TE₀₂/TE₀₃模式回旋管的模拟设计结果。计算采用了坡度磁场,互作用效率得到显著提高。PIC粒子模拟结果表明:在电子注电压25 kV、电流4 A、纵横速度比1.6、工作磁场1.72 T时,回旋管可获得37 kW 的输出功率,横向运动能量转换效率高达51%,器件效率为37%。     

3 mm波段二次谐波渐变复合腔回旋管的非线性模拟

 利用含电流的传输线方程,并在考虑多模注-波互作用及多模耦合的情况下,利用自主开发的多模高次谐波渐变结构复合腔回旋管的注-波互作用数值模拟软件,对3 mm波段二次谐波渐变复合腔回旋管进行了自洽非线性模拟,分析了H₀₂-H₀₃模式对下磁场系数、电流、电子注速度比对注-波互作用效率的影响。计算结果表明,在合适的腔体结构尺寸下,以及合适的磁场系数、电流、速度比下,注-波互作用效率可达27％。     

Stability of a 95-GHz slotted third-harmonic gyro-TWT amplifier

A low-magnetic-field moderate-voltage gyrotron amplifier has been designed for stable high-performance operation at 95 GHz. A slotted interaction circuit is utilized to achieve strong amplification near the third cyclotron harmonic frequency. The start-oscillation conditions were determined by an analytical theory and confirmed by a multimode particle-in cell simulation code. The dominant threat to the amplifier's stability is from a third-harmonic peniotron backward-wave interaction. A slow-timescale particle-tracing simulation code predicts the three-section slotted third-harmonic gyro-TWT, which utilizes an 11.6-kG magnet and a 50-kV 3-A υ_⊥/υ_z=1.4 axis-encircling electron beam with an axial velocity spread of 6% will yield an output power of 30 kW with an efficiency of 20%, a saturated gain of 40 dB, and a constant-drive bandwidth of 2%     

Long Pulse Operation of the THz Gyrotron with a Pulse Magnet

Long pulse operation up to 1 msec of a high frequency gyrotron with a pulse magnet has been successfully carried out in a frequency range including 1 THz. In the experiments, the timing of an electron beam pulse injection is adjusted at the top of the magnetic field pulse, where the variation of field intensity is negligible. The operation cavity modes seem to be TE_{1, 12} and TE_4,12 at the second harmonics. The corresponding frequencies are 903 GHz and 1,013 GHz, respectively. Additionally several features of radiation measurement results of the gyrotron are described and brief considerations are presented.     

Self-consistent field theory and calculation for gyromonotron

A self consistent field large signal theory of gyromonotron is studied in this paper. The RF field profile function satisfies a wave equation. The field is determined by cavity geometry and AC electron beam current. The RF field not only satisfies the boundary conditions at the ends of the cavity but also obeys conservation of energy for steady state interaction between electron beam and field. The parameters of a particular gyrotron are calculated numerically using present theory. Effect of some factors on gyrotron characteristic is discussed. Comparison is made between the results of the self consistent field calculations with and without conservation of energy.     

Network-theoretical model of the gyrotron oscillator part I: Empty cavity oscillation modes

A network-theoretical model of the gyrotron has been elaborated which is both conspicious and rigorous. The problem of self-consistently representing the field in the presence of the electron beam is attacked by expansion into the empty structure oscillation modes. In this first part, a method is presented to determine the empty gyrotron cavity oscillation modes, i.e. theQ factors, resonance frequencies, and field distributions in axisymmetric, but otherwise quite general cavities. It is based on the field representation in terms of local normal waveguide modes. Matrix equations in these modes for different type of cavity sections (building blocks) are formulated. Along with the open resonator boundary conditions, these equations form a nonstandard eigenvalue problem; the eigenvalues are the complex eigenfrequencies, the eigenvectors correspond to the field distributions. By way of example, the method is applied to a simple and a complex cavity.     

1.8 T直流磁体94 GHz连续波二次谐波回旋管

首次实现直流磁体W波段二次谐波回旋管连续波稳定运行。回旋管工作时所需1.8 T磁场由一个水冷直流线圈产生。直流线圈励磁电流为500 A,功耗28 kW,内孔直径66 mm,可直接将回旋管插入内孔中。回旋管内电子束由双阳极磁控注入电子枪产生。采用高效率内置准光模式变换器实现束波分离并输出准高斯波束。研制的回旋管工作频率为94.08 GHz,腔内工作模式为TE₀₂。实验中成功实现5 min连续稳定运行,输出功率达到12 kW。电子束电压为45 kV,电流1.7 A,对应的输出效率15.7 %。