Loading characteristics of an electrostatic coaxial lens

The position of the image is calculated as a function of the position of the object (tubular beam) for an electrostatic system consisting of two coaxial cylinders and an end diaphragm with an annular slit. Zh. Tekh. Fiz. 69, 123–126 (June 1999)     

Electron-optical characteristics of a combined electrostatic lens

The load characteristics of an electrostatic lens consisting of three coaxial cylinders are calculated. The lens is capable of focusing to one point both paraxial annular beams and annular beams away from the axis. In addition, it increases the intensity of a charged particle beam by roughly an order of magnitude compared with a commonly used single axisymmetric lens.     

加载静电压的同轴回旋管放大器的非线性模拟

对一种工作频率为0.14 THz的小轨道同轴回旋管放大器进行非线性模拟,结果表明:通过加载外部静电压的方法,可将回旋管放大器的饱和输出功率提高19%,而且电子束横向与纵向速率比以及横向速度离散对输出功率都没有明显影响,从而可以有效提高回旋管放大器性能. 关键词： 回旋管放大器 静电场 静电离心聚焦系统 饱和功率     

A three-element cylindrical electrostatic lens for a photoelectron spectrometer

The properties of a three-element electrostatic lens for use in photoelectron spectroscope is reported. The lens, which keeps a constant focal position over a wide range of photoelectron kinetic energies, is coupled to a high resolution hemispherical electrostatic analyzer. Maximum utilization of the electron optics is described.     

放电参数对同轴枪中等离子体团的分离的影响

同轴枪中的等离子体团的分离现象主要是由同轴枪内磁场的梯度造成的电流层倾斜而引起的一个增强反馈过程导致的, 这种分离现象越来越成为限制同轴枪有效使用的一个不利因素. 在实验上研究放电参数对等离子体团的分离的影响, 对理论研究和实际应用都具有重要意义. 在实验中发现, 利用光电倍增管可以直接观察到等离子体团的分离程度, 由此可以研究放电参数对等离子体团的分离的影响. 本实验主要研究电容充电电压、电容、放电气压这三个参数对分层现象的影响. 实验发现, 分离程度随着电容以及其充电电压的增大而增强, 随着气压的增大而减弱. 实验结果基于雪犁模型进行分析, 电容以及电容充电电压的增大使放电电流增强使磁场梯度增大而导致电流层的倾斜程度增加, 而使等离子体团的分离程度变严重, 相反, 气压的增加使需要加速更多粒子而导致电流层的倾斜程度减弱, 而使等离子体团分离程度减弱. 分析认为, 通过控制在加速过程中影响电流层倾斜程度的因素可控制共轴枪中等离子体团的分离程度.     

Influence of the edge field on the focusing properties of a coaxial cylindrical lens

The effect of the distance between the grounded flat entrance diaphragm and the outer cylindrical electrode (which determines the edge field of the lens) is investigated over a wide range of variation of the geometry of a coaxial cylindrical lens. It is found that focusing of a charged particle beam on the lens axis is achieved over a wide range only in the case of small clearances between the diaphragm and the outer electrode. It is shown that for an alternative power feed arrangement, in which the outer cylindrical electrode is grounded and the voltage is applied to the inner electrode, beam focusing is in general degraded, in particular on the lens axis. Zh. Tekh. Fiz. 68, 124–127 (June 1998)     

A lens formula for an electrostatic lens accompaning pre- and after electric fields

The virtual object and image are introduced in order to apply the usual lens formula to an electrostatic lense accompaning pre- and/or electric fields. In case of the uniform electric field, their positions are simply expressed as a function of the accelerating or decelerating potential ratio.     

A thin lens formula of the electrostatic bi-potential lenses

A thin lens formula, whose object and image planes are measured from the lens center, is derived for electrostatic bi-potential lenses. Its approximation degree is discussed.     

Computer simulations for intense continuous beam transport in electrostatic lens systems

A code LEADS based on the Lie algebraic analysis for the continuous beam dynamics with space charge effect in beam transport has been developed. The program is used for the simulations of axial-symmetric and unsymmetrical intense continuous beam in the channels including drift spaces, electrostatic lenses and DC electrostatic accelerating tubes. In order to get the accuracy required, all elements are divided into many small segments, and the electric field in the segments is regarded as uniform field, and the dividing points are treated as thin lenses. Iteration procedures are adopted in the program to obtain self-consistent solutions. The code can be used in the designs of low energy beam transport systems, electrostatic accelerators and ion implantation machines.     

Computer simulations for intense continuous beam transport in electrostatic lens systems

A code LEADS based on the Lie algebraic analysis for the continuous beam dynamics with space charge effect in beam transport has been developed.The program is used for the simulations of axial-symmetric and unsymmetricalintense continuous beam in the channels including drift spaces.electrostatic lenses and DC electrostatic accelerating tubes.In order to get the accuracy required,all elements are divided into many small segments,and the electric field in the segments is regarded as uniform field,and the dividing points are treated as thin lenses.Iteration procedures are adopted in the program to obtain self-consistent solutions.The code can be used in the designs of low energy beam transport systems,electrostatic accelerators and ion implantation machines.     

Studies of the characteristic parameters for a flattened-Gaussian beam through a defocusing lens

By introducing an equivalent focal length, analytical propagation equations of the characteristic parameters for a flattened-Gaussian beam through a defocusing lens in free space are obtained on the basis of Collins diffraction formula and definition of high-order intensity moments. The parametric characteristics of beam width, kurtosis parameter and power in the bucket are analyzed and discussed analytically or numerically. Numerical results show that the effects of different kinds or values of defocusing coefficient of the lens on these parameters are different. It is concluded that the action of the lens with different defocusing coefficient can be compensated by a series of lenses with different focal length in theory.     

An electrostatic interpretation of some empirical parameters of light quarks

Values of some arbitrary parameters appearing in a geometrical model for elementary particles developed by MacGregor are compared with quantities associated with classical properties of blocks of charges±e interacting via Coulomb forces and hard-sphere repulsion only. If it is assumed that masses and radii of individual charged particles are related bymc ²=(2/3)(e ²/r) and thatmc ²=6.87 MeV, then the self-energiesM andM ^± of 24-particle neutral blocks and 25-particle charged blocks composed of layers of three octagons and of a square sandwiched by two distorted octagons satisfyM=70.1 MeV,M ^±=74.2 MeV. The binding energyB _nn of pairs of neutral blocks is given byB _nn=4.9 MeV, and the maximum radius of the neutral block is 0.60 F. These four calculated parameter values lie within an average of 1% of the corresponding quantities for nonspinning quarks determined empirically by MacGregor.     

Radial focusing of ion beams in a mass analyzer with an electrostatic lens and a sector-shaped inclined-wall magnetic prism

The ionic and optical properties of an inclined-wall magnetic mass analyzer with electrostatic direction focusing of ions in a nonuniform (r ^?1) magnetic field were studied. A condition for ion focusing in the radial plane was derived, and the basic parameters of the mass analyzer were determined.     

微波同轴腔高阶TM模式参数的计算

用FORTRAN语言编程计算了微波圆柱同轴谐振腔TM工作模式的系列关联参数。给定合适的几何结构参数范围与模式参数范围,就可快速算出同轴腔内所有可能存在的腔体尺寸、本征频率、纵向电场强度极大值的位置对应的半径以及该位置处的特性阻抗。这样,设计者就可以根据特定的需要,从计算出的大量结果中选取符合要求的结构参数,为下一步仿真和实验提供依据,减少了设计初期冗长反复的仿真模拟和试错实验。用3维电磁场软件ISFEL 3D对计算结果进行仿真发现：计算结果与仿真结果有很好的一致性,说明自编程序的计算结果可以作为多注速调管谐振腔设计的优选或优化数据库,可以提高其设计的准确性和效率。     

微波同轴腔高阶TM模式参数的计算

 用FORTRAN语言编程计算了微波圆柱同轴谐振腔TM工作模式的系列关联参数。给定合适的几何结构参数范围与模式参数范围,就可快速算出同轴腔内所有可能存在的腔体尺寸、本征频率、纵向电场强度极大值的位置对应的半径以及该位置处的特性阻抗。这样,设计者就可以根据特定的需要,从计算出的大量结果中选取符合要求的结构参数,为下一步仿真和实验提供依据,减少了设计初期冗长反复的仿真模拟和试错实验。用3维电磁场软件ISFEL 3D对计算结果进行仿真发现：计算结果与仿真结果有很好的一致性,说明自编程序的计算结果可以作为多注速调管谐振腔设计的优选或优化数据库,可以提高其设计的准确性和效率。     

Effects of geometric parameters and electric indexes on performance of a vertical wet electrostatic precipitator

A single-stage, single-wire vertical wet electrostatic precipitator was designed and operated in air–water droplets flow to investigate its performance. The efficiency was compared with a glass micro fiber filter and proposed semi-empirical efficiency model, which was in good accuracy while considering the vapor content. Effects of geometric parameters on efficiency under different charge conditions were discussed. Due to evaporation mechanism, the corona current decreases for high flow rates at the same applied voltage. Findings indicated while developing flow is created inside the ESP, there exists an optimum wire-to-flow inlet spacing that provides maximum droplet collection efficiency.     

放电参数对爆燃模式下同轴枪强流脉冲放电等离子体的影响

同轴枪强流脉冲放电常见有爆燃模式和预填充模式两种放电模式,爆燃模式放电可以得到杂质少、准直性高、输运速度更快的等离子体射流.本实验主要对不同电压及进气量下同轴枪强流脉冲爆燃模式放电的等离子体特性进行了研究.结果表明,在相同放电电压下,进气量少时会有多团等离子体从枪口喷出.随着进气量的增加,同轴枪放电产生的等离子体密度增加,输运速度减小,最终等离子体只有一团从枪口喷出;而在相同进气量下,随着电压的增加,等离子体密度增加,输运速度增大,开始出现有多团等离子体从枪口喷出的现象.产生该现象的原因主要是在放电过程中,当气体持续进入枪底部时,同轴枪底部会产生新的电流通道向前运动,使得在同轴枪出口处观察到了多团等离子体喷出的现象;随着放电电压的增加,在放电过程中回路电流也增加.当电流增加到一定程度时,同轴枪底部就会产生新的电流通道,从而有多个等离子体团从枪口喷出.通过改变充电电容以及对磁探针信号的分析,进一步分析并验证了同轴枪底端多次放电的现象.     

同轴谐振腔高阶横磁模式参数的研究

理论计算和分析了微波圆柱同轴谐振腔高阶横磁(TM)模式的系列关联参数.研究发现：与圆柱腔相比, 同轴谐振腔的TM_n10模式有较大的模式间隔，即工作模式能够远离非工作模式的干扰，这有利于保持器件稳定的频率和功率；在保持腔长不变、腔横截面外半径取特定值时，腔内电场峰值位置的轴向特性阻抗随内径的变化存在极大值；在高频段可以采用任意大横截面的腔体结构和任意阶的模式.计算结果与仿真结果相一致. 关键词： 高阶横磁模式 圆柱同轴谐振腔 特性阻抗 多注速调管