回旋管双阳极磁控注入电子枪的设计

 根据回旋管对电子枪的要求,设计了该双阳极磁控注入电子枪。给出了电极形状、电子轨迹与电子注参量。这种电子枪具有速度零散小、层流性较好、体积小等特点。     

双注磁控注入电子枪

为了增加回旋管的功率,采用双注磁控注入电子枪产生相对论电子注。与双阳极磁控注入电子枪相比,双注磁控注入电子枪产生双束电子注,在不影响电子注质量的基础上,增加电子枪的电流;电子枪产生相同电流时,双注磁控注入电子枪电子注电流小,电子注电子之间的空间电荷效应小,能够降低电子注的速度零散,提高电子注的质量。采用MAGIC软件数值模拟双注磁控注入电子枪,设计出一支大束流、低速度零散的双注磁控注入电子枪。     

全三维94 GHz回旋管系统数值模拟研究

为了打破传统回旋管数值模拟所采用的回旋发射产生理想电子束的局限性, 本文在理论分析94 GHz双阳极磁控注入式电子枪的结构参数的基础上, 通过共形FDTD算法对网格划分进行优化, 得到了具有横纵速度比为1.42, 最大速度零散为5.92%的高性能电子束, 并将此优化后的电子枪取代传统回旋管数值模拟时采用的回旋发射进行该94 GHz回旋 管系统的数值模拟, 并采用MPI四进程并行计算, 最终获得了具有TE₀₃模、94 GHz、平均输出功率约在40 kW、 效率达到10.5%的高性能回旋振荡管. 关键词： 双阳极磁控注入式电子枪 共形FDTD 横纵速度比 速度零散     

回旋管双阳极磁控注入电子枪的设计

根据回旋管对电子枪的要求,设计了该双阳极磁控注入电子枪。给出了电极形状、电子轨迹与电子注参量。这种电子枪具有速度零散小、层流性较好、体积小等特点。     

低速度零散的双阳极磁控注入电子枪设计

根据0.14 THz共焦波导回旋行波管对电子枪的要求,完成了双阳极磁控注入电子枪的设计。使用PIC软件对理论设计得到的结构参数进行了模拟优化,最终得到该枪的电子注横纵速度比为0.75,纵向速度零散1.33%。讨论了电极形状、阴极磁场、控制极电压及发射电流对电子注性能的影响,结果表明,设计过程中应对它们进行充分的优化。     

全三维35 GHz双阳极磁控注入式电子枪数值模拟研究

基于trade-off平衡方程组得到35GHz双阳极磁控注入式电子枪的初始参数,通过编程对其主要参数进行优化设计,并经由自主研发的PIC粒子模拟软件CHIPIC中的电子枪计算模块对其进行全三维的数值模拟研究,最终获得了具有横纵速度比为1.5,最大速度零散约为5.4%的高性能电子枪,能够很好地满足35GHz-100kW回旋振荡管对电子束的要求。     

8 mm二次谐波回旋速调管放大器双阳极磁控注入电子枪的设计

 计算了8 mm二次谐波回旋速调管双阳极电子枪的设计参数，根据这些参数，采用EGUN软件进行模拟和优化，设计出了一只双阳极磁控注入电子枪，该枪的电子束纵横速度比为1.45，速度零散为5.4%，并讨论了电极形状、磁场分布、电流、控制极电压和第二阳极电压对电子注性能的影响，结果发现电子注对这些影响因子非常敏感，设计中应对它们进行充分优化。     

94 GHz单阳极磁控注入式电子枪初始参数设计

根据94 GHz回旋振荡管对电子束的需求,在理论分析电子枪工作原理的基础上通过大量编程对94 GHz单阳极磁控注入式电子枪的一系列参数进行了初始设计, 基于粒子模拟软件CHIPIC开发了专门针对磁控注入式电子枪的计算模块并对其进行了数值模拟。模拟结果显示:该枪的电子束横纵速度比为1.42、速度零散为4.6%,符合回旋振荡管对电子注的要求。     

双阳极回旋管磁控注入电子枪设计

对真实磁场进行拟合,根据电子光学原理以及绝热压缩理论,运用EGUN软件,设计了工作模式为TE34,19的170 GHz回旋管双阳极磁控注入电子枪。最终得到的电子注速度比约为1.3,速度零散小于3%。分析了调节磁场位置、阴阳极间距、阳极间距等因素对电子注性能的影响。结果表明:电子注的速度比和速度零散对于这些影响因子的变化比较敏感,随着阴阳极间距以及阳极间距的增加,速度比逐渐减小,速度零散先减小后增大。设计的双阳极电子枪已应用于整管实验中。     

全三维55GHz双阳极磁控注入式电子枪数值模拟

根据绝热压缩和角动量守恒理论对55GHz双阳极磁控式注入枪进行了初始参数的设计,并利用自主研发的三维粒子模拟软件CHIPIC对其进行数值模拟,通过改变阴极半径、电子注电流、阴极磁场等参数来分析其对磁控注入式电子枪输出结果的影响。最终通过优化参数和综合因素的考虑,得到了横纵速度比为1.44、最大速度零散为5.8%的高性能电子束,能够很好满足55GHz回旋振荡管对电子束的要求。     

0.6 THz三次谐波大回旋电子枪设计

基于会切磁场的理论模型,采用粒子模拟软件对0.6 THz三次谐波的太赫兹回旋管所需的大回旋电子光学系统进行研究。通过大量的模拟计算,分析讨论了不同参数对电子注的横向速度离散、纵向速度离散及横纵速度比的影响,优化了电子光学系统的性能参量,得到符合设计要求且具有工程实际应用的电子枪,该电子枪能够产生55 kV,1 A,横向速度离散为3.39%、纵向速度离散为7.10%、横纵速度比为1.53的大回旋电子注。     

Electron Gun for Powerful Short Pulse Gyrotron with Operating Magnetic Field 8 T

High power short pulse gyrotron with operating frequency 395 GHz operating on the second cyclotron harmonic is now under developing at FIR FU. The gyrotron is planned to use in future experiments for plasma diagnostics. For this purpose the output power about 100 kW and pulse duration 100 ns at least are needed. Preliminary estimations of parameters of some versions of the electron guns with accelerating potential U₀= 70-100 kV were performed. Possibilities of non-adiabatic as well as adiabatic guns were considered. It was shown that non-adiabatic system is not reliable for such rather low value of U₀, the adiabatic magnetron injection gun (MIG) is more preferable for the gyrotron design. Analytical estimations of the suitable MIG dimensions and operating regime to form good quality electron beam were fulfilled. Numerical optimization of the gun shape and position was performed. It was shown that in spite of the extremely big ratio of the operating current (I₀= 18 A) to the Langmuir current of the gun, close to 0.4-0.5, the suggested MIG can form the helical electron beam (HEB) which is suitable for gyrotron operation properties.     

Towards a 1 MW, 170 GHz gyrotron design for fusion application

The electrical design of different components of 1 MW, 170 GHz gyrotron such as, magnetron injection gun, cylindrical interaction cavity and collector and RF window is presented in this article. Recently, a new project related to the development of 170 GHz, 1 MW gyrotron has been started for the Indian Tokamak. TE_34,10 mode is selected as the operating mode after studied the problem of mode competition. The triode type geometry is selected for the design of magnetron injection gun (MIG) to achieve the required beam parameters. The maximum transverse velocity spread of 3.28% at the velocity ratio of 1.34 is obtained in simulations for a 40 A, 80 kV electron beam. The RF output power of more than 1 MW with 36.5% interaction efficiency without depressed collector is predicted by simulation in single-mode operation at 170 GHz frequency. The simulated single-stage depressed collector of the gyrotron predicted the overall device efficiencies >55%. Due to the very good thermal conductivity and very weak dependency of the dielectric parameters on temperature, PACVD diamond is selected for window design for the transmission of RF power. The in-house developed code MIGSYN and GCOMS are used for initial geometry design of MIG and mode selection respectively. Commercially available simulation tools MAGIC and ANSYS are used for beam–wave interaction and mechanical analysis respectively.     

170 GHz回旋管大束流双阳极磁控注入电子枪的分析及设计

 基于绝热压缩原理和强流电子光学理论,设计了一只170 GHz回旋管双阳极磁控注入电子枪,经过理论分析及计算,采用仿真软件进行模拟和优化,最终得到的电子枪的电子注速度比为1.31,横向速度零散度为3.5%,纵向速度零散度为6.1%,束电流为51 A。讨论了阴极磁场、控制阳极电压和第二阳极电压等因素对电子注性能的影响,发现电子注的速度比和速度零散度对这些影响因子的变化都非常敏感:随着阴极磁场的增大,电子注的速度比减小,纵向速度零散度先增大后减小,横向速度零散度先减小后增大;阳极角越接近阴极倾角,纵向速度零散度越小;阳极角向着减小阴阳极间距的方向变化时横向速度零散度变小;增大第一阳极电压可以增大电子注的速度比和电子注的速度零散度。在两阳极电压不变的情况下,增大阴阳极之间的距离会使电子注的速度零散度和电子注的速度比减小。     

Beam Characteristics of Mechanically Tunable Magnetron Injection Guns

Gyrotron has received extensive attention owing to its high-power capability, particularly when the wavelength shrinks below the millimeter-wave range. The electron beam of a gyrotron is typically generated by a magnetron injection gun (MIG), and a mechanically tunable MIG is employed to enhance the beam quality. However, a slight adjustment in the position of the center electrode of the mechanically tunable MIG can cause significant modification of the electric-field profile. Consequently, the cathode current of the mechanically tunable MIG is not only dependent on the cathode temperature, but also the relative position of center electrode. To accurately determine the beam characteristics of the mechanically tunable MIG, an improved computer program is employed to simulate electron trajectories. Simulation and measurement results indicate that although the magnetic field and compression ratio do not influence the beam current of the mechanically tunable MIG, but the beam current of the MIG depends on the cathode temperature and relative position of the center electrode. Finally, an improved mechanically tunable MIG design is developed to enhanced an beam quality while minimizing beam current variation.     

A 35-GHz low-voltage third-harmonic gyrotron with a permanent magnet system

A systematic theoretical and experimental study on a 35-GHz 45-kV third-harmonic gyrotron with a permanent magnet system is presented in this paper. A complex cavity with gradual transition and a diode magnetron injection gun (MIG) are employed in the gyrotron. A self-consistent field nonlinear theoretical investigation and numerical simulation for electron beam interaction with RF fields are given. The diode MIG is simulated numerically utilizing our code in detail. The permanent magnet system provided the maximum axial magnetic field of about 4.5 kG in the cavity region of the gyrotron. The Ka band third-harmonic complex cavity gyrotron with a permanent magnet system has been designed, constructed, and tested. A pulse output power of 147.3 kW was obtained at a beam voltage of 45 kV with beam current of 32.2 A, corresponding to an efficiency of 10.2%.