The theoretical simulation of magnetized electron beam effects on radially polarized of an annular cylindrical piezoelectric crystal

By using the equilibrium equations for a hollow cylindrical piezoelectric layer in absence of body forces and taking into the account a magnetized electron beam in hollow region of this system the effects of thermal pressure, electrostatic self field and the strength of external magnetic field of a non-relativistic magnetized electron beam column on radially polarized of an annular cylindrical piezoelectric crystal in the steady state are simulated. The electrostatic potential profile in piezoelectric layer due to the mechanical pressure and electrostatic self field of electron beam are studied. Furthermore the graphs of the difference of potential Δϕ between inner and outer surfaces of piezoelectric versus to electron temperature, density of beam and the strength of external magnetic field are presented.     

Self-Focusing and de-Focusing of Intense Left- and Right-Hand Polarized Laser Pulse in Hot Magnetized Plasma in the Presence of an External Non-Uniform Magnetized Field

In this paper, self-focusing of an intense circularly polarized laser beam in the presence of a non-uniform positive guide magnetic field with slope constant parameter δ in hot magnetized plasma, using Maxwell’s equations and relativistic fluid momentum equation is investigated. An envelope equation governing the spot-size of laser beam for both of left- and right-hand polarizations has been derived, and the effects of the plasma temperature and magnetic field on the electron density distribution of hot plasma with respect to variation of normalized laser spot-size has been studied. Numerical results show that self-focusing is better increased in the presence of an external non-uniform magnetic field. Moreover, in plasma density profile, self-focusing of the laser pulse improves in comparison with no non-uniform magnetic field. Also, with increasing slope of constant parameter of the non-uniform magnetic field, the self-focusing increases, and subsequently, the spot-size of laser pulse propagated through the hot magnetized plasma decreases.     

Dynamics of neutralized charged particle beams in external magnetic and self fields

The dynamics of charged particle beams under the influence of their self-magnetic field and an external magnetic field is examined on the basis of equations for the trajectory of a boundary particle. A study is made of the change in the dynamics of fast particles due to the influence of the electric field of the partially neutralized space charge of the beam, the stationary electric field, and the field of the oscillations in the quasineutral beam plasma. Changes in the total beam energy caused by the self-electric field and in the longitudinal velocity owing to the self-magnetic field are taken into account. Zh. Tekh. Fiz. 68, 106–109 (August 1998)     

Nonlinear theory of beam excitation of azimuthal surface modes in plasma-filled cylindrical metal waveguides

It is shown that electromagnetic surface waves propagating along the azimuthal angle can be excited efficiently by an annular electron beam in a cylindrical metal waveguide partially filled with a magnetoactive plasma. A self-consistent system of differential equations is obtained to describe the nonlinear interaction between the beam particles and an azimuthal surface wave in the single-mode regime. This system of equations is analyzed numerically and the influence of the parameters of this waveguide structure on the development of the resonant beam instability is determined. Zh. Tekh. Fiz. 69, 84–88 (July 1999)     

层流平衡相对论电子束束流特性的数值计算

通过对层流平衡相对论电子的运动微分方程组进行数值求解,得到正则角动量在pθ=0,pθ=const.和pθ∝r2三种情况下,束流的传输特性.针对pθ=0的相对论实心电子束,利用数值求解得到了与解析方法一致的结果,从而验证了数值方法的合理性;针对无法用解析方法求解的pθ=0环行电子束、pθ=const.和pθ∝r2的情况,利用数值方法得到了束流和空间极限电流关于波导、电子束结构和二极管电压等参数的变化规律及对轴向导引磁场的要求.计算结果表明:当相对论电子束以层流平衡态传输时,环行束较实心束具有更高的空间极限电流和更低的轴向导引磁场,且当阴极发射面与导引磁场的磁场线垂直时,维持电子束层流平衡所需的轴向导引磁场最低;电子束在有限磁场导引下以层流平衡态传输时,空间极限电流明显大于无限大磁场导引下一维近似的情况.利用数值方法对层流平衡相对论电子束进行理论研究,更全面地揭示了电子束在正则角动量满足不同条件时的束流特性,为设计新型结构的高功率微波器件提供理论参考.     

有限引导磁场下相对论环形电子注色散特性的研究

采用等效媒质处理方法来研究有限引导磁场下沿纵向运动的相对论环形电子注.首先建立运动坐标系以电子注纵向速度匀速运动,在运动坐标系中电子注可以被考虑成静止的磁化等离子体,再通过四维空间的洛伦兹变换得到电子注在静止的实验室坐标系下可以被等效为双各向异性媒质,其不仅具有张量形式的电导率和磁导率,还具有手征特性.在此基础上同时考虑了由于电子注表面波动所引起的表面电流密度.采用该方法研究了有限引导磁场下圆柱波导中沿纵向运动的相对论环形电子注,推导出该模型的色散方程,并进行了数值计算.计算结果表明该研究方法能够得到更准 关键词： 相对论环形电子注 磁化等离子体 色散特性     

On the effect of a magnetic field on fast charged particles passing through a substance

A transport equation in the small-angle approximation is obtained for a curvilinear beam of fast charged particles passing through a substance in a nonuniform magnetic field. Green functions for this equation are found for an annular beam in a weak-focusing field and for a helical beam in the nonuniform magnetic field.     

Some properties of the envelope equations used in the design and adjustment of electron-optical beams

An analytical transformation of the usual envelope equations is used to derive scale transformation equations for a first-order electron-optic lens. Analysis of these equations, which take into account both the particle temperature and the particle space charge, leads to the identification of certain general principles for constructing and scaling beam systems of various types. The properties of the transformation are illustrated by the example of the equations for an axisymmetric electrostatic lens. Zh. Tekh. Fiz. 68, 96–102 (January 1998)     

Time-resolved measurement technique for pulsed electron beam envelope basing on framing and streaking principle

The time-resolved electron beam envelope parameters, including cross sectional distribution and beam centroid position, are very important for the study of beam transmission characteristics in a magnetic field and for verifying the rationality of the magnetic field parameters employed. One kind of high time-resolved beam envelope measurement system has recently been developed, constituted of a high-speed framing camera and a streak camera.It can obtain three panoramic images of the beam and time continuous information along the given beam profile simultaneously. Recently obtained data has proved that several fast vibrations of the beam envelope along the diameter direction occur during the front and the tail parts of the electron beam. The vibration period is several nanoseconds. The effect of magnetic field on the electron beam is also observed and verified. Beam debugging experiments have proved that the existing beam transmission design is reasonable and viable. This beam envelope measurement system will establish a good foundation for beam physics research.     

CSR电子冷却系统强流电子束包络的振荡特性

 HIRFL CSR的电子冷却系统是采用强流电子束对重离子束进行冷却。在冷却段漂移管区，由于强流电子束自身的空间电荷场和螺线管磁场的作用，使得电子束的包络发生振荡。通过求解电子束的横向包络方程，研究了强流电子束包络随电子束参数和螺线管聚焦磁场的变化关系。计算结果表明：对于不同的电子束能量和磁场，电子束包络的振荡频率也不相同；在相同的条件下，磁场越强，电子束包络振荡幅度越小，电子束能量越大，其包络的振荡频率也越快。     

A self-consistent method for describing curvilinear charged beams

A self-similar solution to the self-consistent gasdynamics equations is used to derive envelope equations for a thin curvilinear charged beam propagating in an external electromagnetic field.     

Scaling studies and time-resolved microwave measurements on arelativistic backward-wave oscillator

A relativistic backward-wave oscillator (BWO) operating at a frequency near 8 GHz has been built. The parameters of the 60-ns electron beam driving this microwave source are varied over the ranges 0.8-1.5 MV and 2-10 kA. Several different annular cathodes for launching the electron beam are tried, varying the outer radius and shape. The axial magnetic field guiding the beam through the BWO is varied between 0.6 and 3 T. The power transfer downstream to an output waveguide is investigated as a function of the shape of the transition from the BWO to the waveguide. The scaling of the output power and frequency with these variations is discussed. Time-resolved measurements of 2-ns-long segments of the microwave output are shown. In observations of the microwave signal, it is found that the frequency shifts as the output power envelope passes through a sharp dip. It is proposed that this shift corresponds to a change in the longitudinal operating mode of the BWO     

直线感应加速器束心偏移轨迹的计算

给出了直线感应加速器在磁体失准情况下电子束质心运动轨迹的计算机模型.利用坐标变换求磁体失准后的三维磁场分布,并采用束包络方程和束心偏移方程耦合求解的方法计算束心的运动轨迹.磁体失准度与束流质心偏移的定量关系的计算研究对磁体安装定位及校正线圈使用是有意义的.     

周期永磁磁场导引环形强流电子束研究

 利用磁场有限元法，计算了周期性布置的永磁铁内的磁场；利用流体模型分析了作用在束电子上的力并导出了改进Matheiu函数形式的径向力方程；利用2.5维PIC程序研究了束传输的物理过程。计算发现强流相对论电子束的稳定传输与束等离子体密度、束平衡位置、磁场的强度、磁场周期长度等有关。研究认为利用周期性永磁场导引数kA的环形电子束，使之稳定传输是可能的。     

Influence of the magnetic field of current extracting systems on motion of an electron beam

In the present work, the influence of the magnetic field of current extracting systems on motion of electrons and envelope of the electron beam transported in preliminary created plasma in an external longitudinal magnetic field to a current-conducting target is examined. The field generated by the electron beam, the external magnetic field, and the magnetic field created by the current running down the target during electron deposition are taken into account. Configuration portraits of the beam on the target are constructed as functions of the beam current, degree of current neutralization, external field strength, and orientation of the current extractors. __________ Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 5, pp. 44–47, May, 2006.     

圆对称环域Josephson隧道结的静态特性(Ⅰ)——准衍射现象和自场效应

本文研究了圆对称环域Josephson隧道结的静态特性。在环带宽度较窄的情形下,不计入自场,并考虑到外磁场在结区内的非均匀性,解析地得到了l_m与外磁场的l_H的关系。与典型的小结衍射图形所不同的是所有极小都不为零,表现出准衍射图形特征。在环带宽度较宽的情形下,对自场方程进行了数值计算,得到其与一般一维结不同的结特性。 关键词：     

Coaxial Relativistic Backward Wave Oscillator and Coaxial Master Oscillator-Power Amplifier

A two and one half dimensional particle-in-cell code MAGIC has been used to investigate the nonlinear beam-wave interaction in a coaxial relativistic backward wave oscillator(RBWO) and optimize the dependence of the output power on electron beam nature parameter, slow wave structure geometry and magnetic guide field. The optimum conditions for the coaxial RBWO were obtained. The simulation results show: the coaxial RBWO can generate 3.2GW peak output power at 10.2GHz in the TM₀₂ made when an annular electron beam of 20KA is accelerated across a diode potential of 600KV and guided through a section of uniform coaxial corrugated waveguide by an axial magnetic field of 25KG, the peak efficiency is about 27% . A novel coaxial master oscillator–power amplifier was presented in this paper.     

Influence of nonuniformities of a magnetic-mirror field on the space-time characteristics of a long-pulse relativistic electron beam

An experimental investigation is made of the influence of local nonuniformities of a mirror-configuration magnetic field on oscillations of the space charge and the structure of a long-pulse relativistic electron beam. It is found that the outcome depends on the axial configuration of the nonuniformity. A nonuniformity near the cathode can substantially reduce the amplitude of the oscillations and improve the beam transport. The creation of a nonuniformity far from the cathode leads to an accelerated increase in the oscillations and causes spreading of the transverse structure of the beam. A possible explanation is given for the mechanism responsible for the influence of these local magnetic field nonuniformities assuming reflection of the cathode plasma and electron flux from the magnetic mirror, and also allowing for a jump in the drift velocity. Zh. Tekh. Fiz. 67, 83–88 (August 1997)     

Theory of stimulated nonresonant emission from relativistic beams

A study is made of the radiative Pierce instability of a relativistic electron beam in a waveguide stabilized by an infinitely strong magnetic field. Analytical and computational methods are used to determine the growth rate of the instability, as well as the efficiency for conversion of the beam energy into electromagnetic field energy as a function of the beam current, how relativistic the beam is, and the geometry of the system. The physical nature of the instability is clarified and the mechanisms for its saturation are discussed. Zh. éksp. Teor. Fiz. 115, 2037–2050 (June 1999)     

Controlling Beam Halo-Chaos by Adaptive Control Exterior Magnetic Field

In this paper, the parametric adaptive method for controlling the beam halo-chaos in the periodic focusing channels of high-current proton linacs is presented. The study of proton beam halo-chaos based on controlled beam envelope equation and the results of particles-in-cell simulations for macro-particle beam show that the proton beam chaotic envelope as well as the beam rsm radius can be controlled to the beam matched radius using this method.For the Kapchinskij-Vladimirskij (K- V) distribution of initial proton beam, all statistical physical, quantities of the beam halo-chaos are largely reduced. This control method has an advantage of the control halo-chaos since the exterior magnetic field as controlled parameter can be rather easily adjusted in the periodical magnetic focusing channels for the experiment.