双阳极磁控注入枪束流特性的研究

 介绍了用于34GHz基波回旋速调管的双阳极磁控注入枪的结构特点，为了准确分析磁控注入枪的束流特性，建立了阴极表面理论模型，用新编制的程序模拟了电子轨迹。模拟和测量结果显示磁场对磁控注入枪的束流有影响，磁控注入枪的束流也与阴极温度和空间电荷效应有关系。     

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。     

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。     

1THz回旋管双阳极磁控注入电子枪的分析及设计

基于电子光学理论,通过编程进行大量的数值计算,设计了一支用于1THz回旋管的双阳极磁控注入式电子枪.对双阳极磁控注入电子枪的计算及设计进行了阐述,并对1 THz回旋管电子枪中高磁压缩比(f_m=125)可能导致电子反转的问题进行了详细的分析和模拟.通过对电子枪进行了仿真和优化,最后计算和设计了一支速度比适中(α=1.3),速度零散较小(Δβ<8%) 的电子枪.     

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。     

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。     

28 GHz/50 kW准光输出连续波回旋管

研制出国内首支基于电子回旋加热应用的28 GHz/50 kW准光输出大功率连续波回旋管。该回旋管采用了双阳极磁控注入枪,TE₀₂模式谐振腔,内置准光模式变换器,单级降压收集极。回旋管采用无液氦制冷超导磁体提供稳态磁场。实验中成功实现54.8 kW/1 s短脉冲输出和45.8 kW/30 s的连续波输出,工作频率为28.08 GHz,总效率达到57%。     

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。     

回旋管单阳极电子枪计算机辅助设计

 根据回旋管对电子枪的要求，采用综合法和分析法设计了该单阳极磁控注入电子枪。编制了一套大型的计算程序，利用计算机辅助设计，给出了电极形状、电子轨迹与电子注参量。计算表明，这种电子枪具有速度零散小、层流性较好、体积小等特点。该枪已用于制管实验中。由热测实验表明，它具有明显的优点，并获得了127kW的峰值功率和超过10%的效率。     

基于BEM泊松方程求解的空间电荷效应数值模拟

 为了模拟强束流在加速器及其传输线中的行为,用C++语言开发了一种包含空间电荷效应的多粒子跟踪程序(PTP-SC),它在经典的PIC方法基础上,基于边界元法(BEM)和非等距的网格求解泊松方程。束流在自由空间分布的仿真结果与解析结果保持较好的一致性。给出了一条注入线的模拟计算结果,并与ORBIT,TRACE 3-D的计算结果进行比对。结果表明：该程序与采用数值方法的ORBIT程序的计算结果有较好的一致性。该程序可用于直线加速器及回旋加速器中的空间电荷效应模拟。     

磁控注入电子枪的研究

介绍了毫米波回旋速调管磁控注入电子枪的结构与特点.依据回旋管对电子枪的要求,考虑相对论效应和空间电荷效应,编制了一套计算程序.利用电子枪模拟程序对电子轨迹进行模拟计算,研究了电极形状、磁场分布以及电子轨迹与电子注参量的影响,为磁控注入电子枪的设计提供了理论依据. The Structure and characteristics of the magnetron injection gun (MIG) for mm wave gyro-klytron are introduced. According to the requirements for the gyro-klytron, the relativistic effect and the space charge effect is taken into account . A program is developed for CAD. An electron gun code is used to simulate the electron trajectory, the influence of electrode shape, magnet field, electron trajectory on the electron beam have been studied. The theory for design of the electron gun is presented.     

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.     

Improved Computer Program for Magnetron Injection Gun Design

Gyrotron has received extensive attention owing to its high-power capability, especially when the wavelength shrinks below the millimeter-wave range. The electron beam of a gyrotron is typically generated by a magnetron injection gun (MIG). For high cathode current density, the MIG may operate in a region that combines temperature limited and space-charge limited emissions. An improved computer program for electron gun design is appropriate for MIGs that operate between space-charge limited and temperature limited emission. Moreover, the initial input formation of the program resembles that of the EGUN code. Analysis of a Pierce electron gun and MIGs reveals that the stimulated beam current appears consistent with the measured results. However, EGUN simulation results in which the cathode emitters of MIGs are chosen for the temperature limited emission differ from those of our simulation results. This difference is most likely owing to that the initial emitting energy can not be completely described in the EGUN simulation. Finally, the improved computer program is used to design a MIG for a Ka-band, TE₀₁ mode gyro-TWT.     

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%.     

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.     

Design of a 3-MW 140-GHz gyrotron with a coaxial cavity

A design for a 3-MW 140-GHz gyrotron based on the use of a coaxial cavity is given. The cavity mode is TE_21,13, chosen so that the ohmic heating on both the inner and outer conductors would be low enough for CW operation. The mode selection process, nonlinear, multimode and time-dependent modeling of the beam wave interaction, and gun design are discussed in detail. An inverted magnetron injection gun (MIG) is used to accommodate the inner conductor. The radiation is coupled out via a quasi-optical mode converter, consisting of an irregular cylindrical waveguide section followed by a step-cut launching aperture and a single near-parabolic mirror. The design of these components is also described     

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.