采用坡度磁场提高同轴腔电子回旋管的效率

通过选择适当电子初始的横纵向速度比,并引进坡度磁场的方法,来提高同轴腔电子回旋微波激射器效率。非线性模拟表明,用这种办法可以将德国卡尔斯鲁研究中心研制的同轴腔电子回旋微波激射振荡器的实验效率,从26.7%提高到31.5%。这种效率放大的物理机制是：坡度磁场改变了相对论电子的运动条件,有效地改善了波束互作用过程中电子的群聚状态,使电子束有更多的动能转换为电磁能,从而提高了电子束的换能效率。     

同轴腔自由电子回旋脉塞的输出功率

 介绍了同轴腔自由电子回旋脉塞输出功率受电子束错位的影响,并就德国卡鲁斯研究中心(FZK)正在建造的波长为2mm、输出功率为1.5MW的同轴腔回旋脉塞,进行了数值计算分析。结果表明:电子束错位会使输出功率下降,但对工作模TE_82,16,1模的影响,比对竞争模TE_27,16,1模的影响更小。     

同轴腔自由电子回旋脉塞的输出功率

介绍了同轴腔自由电子回旋脉塞输出功率受电子束错位的影响,并就德国卡鲁斯研究中心(FZK)正在建造的波长为2mm、输出功率为1.5MW的同轴腔回旋脉塞,进行了数值计算分析。结果表明:电子束错位会使输出功率下降,但对工作模TE82,16,1模的影响,比对竞争模TE27,16,1模的影响更小。     

静电电子回旋脉塞与静电自由电子激光

笔者提出了静电电子回旋脉塞的概念,并在三位博士生的共同努力下,建立了静电电子回旋脉塞的线性及非线性理论。接着,笔者又提出利用静电回旋系统建立静电自由电子激光的概念(此种静电自由电子激光目前在国际上简称为Orbitron自由电子激光),随即又建立了这种自由电子激光的线性理论并进行了数值计算。 陈晓东、欧阳征标和硕士生徐晓曦在他们的学位论文中,完成了静电电子回旋脉塞机理的实验论证工作。实验结果和理论计算较好地相符。 上述一系列的工作均已得到国际的公认。本文就是这一系列工作的基本总结。     

内导体倾斜的内开槽同轴回旋管

同轴回旋管中不可避免发生内导体倾斜。主要研究了内导体倾斜对特征根、Q值、谐振频率、横向电场、模式竞争和电子效率的影响,并以170 GHz TE_{31, 12}内开槽同轴回旋管作为实例对内导体倾斜理论进行验证。结果表明,特征根和Q值随倾角θ增大而略微增加。在0~0.5°范围内,当θ稍微增大时,电子互作用效率稍微减少。如果θ增加到1.3°,则由于模式竞争严重,且横向电场畸变严重,电子互作用效率降低到只有5%。受内导体倾斜的影响, 随着θ增加,无论热腔还是冷腔,谐振频率都稍微增大。     

同轴腔高阶模式回旋管振荡器中多模起振过程的非线性模拟

给出了工作在高阶模式下的同轴腔回旋管振荡器,在考虑竞争模式情况下的多模起振过程的数理模型和具体的数值计算方法。以此为基础编制的程序对一只工作于高阶模式TE42, 22,频率为0.22 THz的同轴腔回旋管振荡器进行了多模非线性模拟研究。结果表明：在合适的腔体结构参数并考虑腔壁上的欧姆损耗情况下,竞争模式得到有效抑制,可以稳定地工作在单一模式,输出功率达0.87 MW,效率为22.8%,腔壁上的欧姆损耗低于其所能承受的最大值。     

全三维110GHz和220GHz同轴腔双注回旋管数值模拟研究

为了打破传统单注回旋管只能产生较低功率的局限性, 本文基于自主研发的PIC粒子模拟软件CHIPIC 对110 GHz和220 GHz同轴腔双注回旋管进行全三维数值模拟研究. 在理论分析同轴双电子注电子枪设计模型和初始参数的基础上通过CHIPIC对其进行优化设计, 得到了具有横纵速度比为1.0, 最大速度零散约为5.4%的高性能电子束; 并将此优化后的双阳极双注电子枪取代传统回旋管数值模拟时采用的回旋 发射进行110 GHz和220 GHz双注回旋管整管的数值模拟, 并采用MPI四进程并行计算, 最终获得了具有双频分别为110 GHz和220 GHz、模式为TE₀₂模、平均输出功率约在70 kW、 效率达到8.75%的高性能双注回旋振荡管. 关键词： 同轴腔双注回旋管 同轴双电子注电子枪 横纵速度比 速度零散     

HL-2A装置ECRH回旋管磁场分布测量

HL-2A装置的电子回旋系统使用了俄罗斯进口的新型回旋管，在俄罗斯专家的协助下，去年将其安装完毕，并且投入了实验运行，取得了丰富的实验数据和良好的实验参数。     

回旋管同轴谐振腔模式的选择

 为了研究回旋管工作模式的选择机理,分析了圆柱波导开放式谐振腔、光滑同轴谐振腔和纵向内开槽同轴谐振腔相应波导的色散特性,进而研究了这些谐振腔内模式竞争的问题。对同轴结构波导色散方程作了相应的数值计算,结果表明,同轴谐振腔利用自身色散曲线与谐振腔内外半径比值的数值关系,能够使在开放式谐振腔内无法工作的高阶模式在其内部稳定工作。最后,以德国卡尔斯鲁厄理工学院(KIT)研制的同轴回旋管为例,进行了相应的分析计算,结果表明纵向内开槽同轴谐振腔相对于光滑同轴谐振腔更适合高阶模式的稳定工作。     

回旋管同轴谐振腔模式的选择

为了研究回旋管工作模式的选择机理,分析了圆柱波导开放式谐振腔、光滑同轴谐振腔和纵向内开槽同轴谐振腔相应波导的色散特性,进而研究了这些谐振腔内模式竞争的问题。对同轴结构波导色散方程作了相应的数值计算,结果表明,同轴谐振腔利用自身色散曲线与谐振腔内外半径比值的数值关系,能够使在开放式谐振腔内无法工作的高阶模式在其内部稳定工作。最后,以德国卡尔斯鲁厄理工学院(KIT)研制的同轴回旋管为例,进行了相应的分析计算,结果表明纵向内开槽同轴谐振腔相对于光滑同轴谐振腔更适合高阶模式的稳定工作。     

同轴回旋自谐振脉塞放大器的线性分析

 从同轴回旋自谐振脉塞(CARM)放大器的回旋动力学理论入手,详细分析了各参量对同轴CARM放大器的线性增益的影响。通过数值模拟,发现该器件的线性增益对及对同轴波导的外半径、电子导引中心半径以及加速电压的变化非常敏感,而随波导内半径的变化不敏感。经优化,当外半径为3.805 cm,导引中心半径为1.309 cm,内半径为1.039 cm,加速电压为54.9 kV时,器件的线性增益最高为294.96 dB/m。     

Magnetic field tapering in the KfK coaxial gyrotron

Equations describing the magnetic field tapering in a gyrotron cavity with allowance for the dependence of the radius of the electron guiding centers on the longitudinal coordinate are derived. Influence of the shift of the magnet of the KfK coaxial gyrotron along the gyrotron axis onefficiency is studied. It is found that for the operating voltage 90kV the optimal alignment is such that the maximum of the magnetic field is placed in the middle of the straight section of the cavity. For 80kV the absolute values of the field must be reduced by factor 1.017, or the maximum of the field must be placed in the output taper of the cavity.     

A scheme to enhance the conversion efficiency of slow‐wave electron cyclotron masers in the large signal approximation

Based on the anomalous Doppler effect, we propose a scheme to improve the practicability of slow‐wave electron cyclotron masers in the large signal approximation. This scheme simultaneously contains the tapered guiding magnetic field and tapered refractive index. Numerical calculations show that this scheme enables the conversion efficiency to reach a higher value within a shorter time than previous schemes. Besides, this scheme also works well in the cases of THz wave band and beam axial‐velocity spread.     

基于Tesla变压器和螺旋线的长脉冲发生器

提出了一种结构紧凑的长脉冲发生器，该发生器的螺旋型形成线包含有磁性材料构成的内导体棒和外屏蔽。形成线通过内置的高耦合Tesla变压器充电，变压器的初级线圈紧靠外磁芯导体，次级线圈位于螺旋中筒和外筒之间。对这种结构的螺旋线进行了特征参数的理论计算和波传输数值模拟，并进行了简单的原理验证实验。实验结果表明:这种设计是合理的、可行的。     

Operation of the quasi-optical gyrotron at harmonics of the gyrofrequency

This paper investigates the performance of a quasioptical gyrotron, when the electron beam interacts with the radiation fields at harmonics of the gyrofrequency. The nonlinear equations of motion are obtained in the slow-timescale. The expression for the linear gain is derived and the conditions for excitation are given (frequency threshold, optimal operating point, bean current and resonator quality thresholds). In the nonlinear regime, it is shown that maximum efficiencies comparable to those at the fundemental (50%) are possible, albeit at a prohitively high radiation field amplitude, while realistically feasible field amplitudes can give somewhat smaller, but nevertheless still high efficiencies (15%). Finally, the results are suplemented by empirical scaling laws, useful for experimental designs.     

Self-consistent nonlinear analysis of overmoded gyrotron oscillators

The self-consistent nonlinear analysis is presented for an overmoded gyrotron, in which the gyrotropic beam interacts with more than one cavity eigenmodes. The nonlinear equations are obtained in the slow time scale for the motion of each individual particle and for the evolution of the amplitude and frequency of each individual cavity eigenmode. A numerically efficient algebraic longtime-step algorithm is developed, which includes magnetostatic field tapering and time transients. Numerical examples are presented for the excitation and competition of the cavity eigenmodes.Work supported by the U.S. Naval Research Laboratory, Plasma Physics Division, under Contract No. N00173-79-C-0200.     

Development of the Highly Homogeneous Magnetic Field for Simulative Gyrotron by HTS

The low temperature superconducting magnet system, with the highly homogeneous magnetic field, has been applied extensively, and has had important effects on many domains. With the development of the cryogenic and superconducting techniques, it is possible that high temperature superconducting magnet with highly homogeneous magnetic field is manufactured by high temperature superconductor（HTS）. Therefore, a simulative gyrotron applied into war, with highly homogeneous magnetic field, is designed and manufactured by high temperature superconducting material.     

Effect of cavity geometry on the performance of a gyrotron

The effect of interaction cavity geometry on the gyrotron performance in terms of cold cavity parameters (Q value and axial electric field profile), Ohmic wall loss, start oscillation current and interaction efficiency are analyzed in detail in this article. The measurement of Q value and axial electric field profile is also performed for the cavities with different geometries by using non-destructive and perturbation techniques, respectively. Scattering matrix code is used for the computation of Q value and axial electric field profile and results are compared with the experimental data. A Particle-in-Cell code and a specific beam–wave interaction computation code based on generalized non-linear theory are used in the efficiency calculations. For all numerical and experimental analyses, the case of 42 GHz, 200 kW gyrotron is considered here.