共查询到19条相似文献,搜索用时 343 毫秒
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均匀聚焦系统和周期性聚焦系统中束晕形成的模拟研究 总被引:3,自引:1,他引:2
首先采用束核-试验粒子模型,利用Poincare截面法,讨论了均匀聚集系统和周期性聚集系统中,由强流带电粒子的自场效应所导致的非线性共振及混沌现象.然后按照自治理论,进一步对相空间中的初始粒子分布分别满足水袋型、抛物线型以及高斯型等相空间分布情况下进行了模拟计算,并得到了一系列结果诸如束晕强度、发射度增长随失配因子及调谐衰减变化等. 相似文献
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共振、混沌与束晕形成 总被引:3,自引:0,他引:3
研究强流束中的非线性共振、混沌与束晕形成的关系.给出强流束中非线性共振范围的表达式及其随束流空间电荷效应变化的数值结果和图表曲线,提出由非线性共振而激发的束晕形成的空间电荷效应极限,并分析束晕形成的过程. 相似文献
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周期聚焦磁场中束晕-混沌的简单函数控制 总被引:1,自引:0,他引:1
本文采用粒子-束核模型,基于束晕-混沌的非线性控制策略,对周期性聚焦磁场中满足K—V分布的离子束进行模拟研究,提出了控制其束晕-混沌的简单函数控制器,并给出具体的实施方案.数值模拟研究表明,运用这种方法可以消除束晕及其再生现象,达到对束晕-混沌的有效控制. 相似文献
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详细推导了AVF型験旋加速器中束团粒子在曲线坐标系中的动力学方程(考虑和不考虑空间电荷相互作用力两种情况).在假定动力学方程中各参数值的前提条件下,用Lunge-Kutta方法对考虑空间电荷时的动力学方程进行了数值计算.结果表明,束晕的形成和发展同样也是强流験旋加速器中束流损失的一个主要原因.但束晕形成的机制不同于直线加速器的情况,它不是由共振和混沌引起,而是由于粒子的排斥运动和束团内粒子的涡流运动引起的. 相似文献
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研究了周期性聚焦磁场通道中,束晕-混沌的外部磁场滑模变结构控制方法。通过选择适当的滑模函数,根据李雅普洛夫稳定性条件,推导出外部磁场的滑模变结构控制器。模拟结果表明,在控制条件下,混沌变化的束包络半径能被控制到匹配半径。将该方法应用在多粒子模型中,实施每隔一个磁场周期就调节一次磁场幅度的控制策略,可实现对初始分布为K-V分布离子束的束晕-混沌的有效控制,束平均发射度降低了80%左右,束晕强度因子变为0,束流质量得到了很好的改善,消除了束晕及其再生现象。由于外部磁场是可测和可调的物理量,控制器简单且利于实现,研究结果可为强流离子加速器中周期性聚焦磁场的设计与试验提供参考。 相似文献
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Stability and transport properties of an intense ion beam propagating through an alternating-gradient focusing lattice with initial Kapchinskij-Vladimirskij (KV) distribution are studied using newly-developed perturbative (δf) particle simulation techniques. Stability properties are investigated over a wide range of beam current and focusing field strength. In the unstable region, large-amplitude density perturbations with low azimuthal harmonic numbers, concentrated near the beam surface, are observed. Their nonlinear consequences are discussed. 相似文献
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In this paper, the nonlinear transport of intense bunched beams in electrostatic quadrupoles is analyzed using the Lie algebraic method, and the results are briefly presented of the linear matrix approximation and the second order correction of particle trajectory in the state space. Beam having K-V distribution and Gaussian distribution approximation are respectively considered. A brief discussion is also given of the total effects of the quadrupole and the space charge forces on the evolution of the beam envelope. 相似文献
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In this paper, the nonlinear transport of intense bunched beams in electrostatic quadrupoles is analyzed using the Lie algebraic method, and the results are briefly presented of the linear matrix approximation and the second order correction of particle trajectory in the state space. Beam having K-V distribution and Gaussian distribution approximation are respectively considered. A brief discussion is also given of the total effects of the quadrupole and the space charge forces on the evolution of the beam envelope. 相似文献
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Reza Fallah Reza Khooniki Seyed Mohammad Khorashadizadeh Ali Reza Niknam 《等离子体物理论文集》2021,61(2):e202000086
The influence of relativistic-ponderomotive nonlinearities and the plasma inhomogeneity on the nonlinear interaction between a high-power laser beam and a warm underdense plasma are studied. It is clear that the relativistic ponderomotive force and the electron temperature modify the electron density distribution and consequently change the dielectric permittivity of the plasma. Therefore, by presenting the modified electron density and the nonlinear dielectric permittivity of the warm plasma, the electromagnetic wave equation for the propagation of intense laser beam through the plasma is derived. This nonlinear equation is numerically solved and the distributions of electromagnetic fields in the plasma, the variations of electron density, and plasma refractive index are investigated for two different background electron density profiles. The results show that the amplitude of the electric field and electron density oscillations gradually increase and decrease, during propagation in the inhomogeneous warm plasma with linear and exponential density profiles, respectively, and the distribution of electron density becomes extremely sharp in the presence of intense laser beam. It is also indicated that the electron temperature and initial electron density have an impact on the propagation of the laser beam in the plasma and change the plasma refractive index and the oscillations' amplitude and frequency. The obtained results indicate the importance of a proper choice of laser and plasma parameters on the electromagnetic field distributions, density steepening, and plasma refractive index variations in the interaction of an intense laser beam with an inhomogeneous warm plasma. 相似文献
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B. V. Kholomai 《Russian Physics Journal》1978,21(7):865-870
The distribution function of electrons moving in an axially symmetric focusing magnetic field is constructed. The macromotion and self-field of the beam are taken into account. The nonrelativistic and relativistic limits are discussed. Upon switching off the magnetic field the distribution functions obtained change into the Maxwell-Boltzmann distribution. The motion of charged particles in a focusing magnetic field is the simplest model for investigation of a beam of particles, for example, electrons, in storage or accelerator rings. In accordance with the well-known theorem of N. Bohr, a magnetic field has no effect on the distribution function for a one-dimensional distribution of electrons with respect to the momenta. However, the situation is altered if macromotion occurs in a static system, for example, the revolution of electrons in storage or accelerator rings. Maintaining the focusing of the beam in an equilibrium orbit, the magnetic field thereby affects the electron distribution function. For an actual electron beam the distribution function is determined by the initial conditions of formation of the beam; however, as a result of scattering processes it will approach some steady-state equilibrium distribution function. We will discuss the problem of finding such a distribution function in the nonrelativistic and relativistic cases.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 7, pp. 35–40, July, 1978.The author thanks Professor I. M. Ternov of Moscow University for his constant interest in this research and Professor V. G. Bagrov of Tomsk University for help in the research. 相似文献
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Potential of an Elliptic Cylinder with the Space Charge Uniformly Distributed over the Cross Section
V. A. Syrovoi 《Physics of Particles and Nuclei Letters》2018,15(3):269-271
The field of an intense charged-particle beam in the form of a cylinder with the elliptic cross section is discussed. The models used hitherto are not adequate. 相似文献
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Pakter R. Chiping Chen 《IEEE transactions on plasma science. IEEE Nuclear and Plasma Sciences Society》2000,28(3):502-510
Electron beam halo formation is studied as a potential mechanism for electron beam losses in high-power periodic permanent magnet focusing klystron amplifiers. In particular, a two-dimensional (2-D) self-consistent electrostatic model is used to analyze equilibrium beam transport in a periodic magnetic focusing field in the absence of a radio frequency (RF) signal, and the behavior of a high-intensity electron beam under a current-oscillation-induced mismatch between the beam and the periodic magnetic focusing field. Detailed simulation results are presented for choices of system parameters corresponding to the 50-MW, 11.4-GHz periodic permanent magnet (PPM) focusing klystron experiment performed at the Stanford Linear Accelerator Center (SLAC). It is found from the self-consistent simulations that sizable halos appear after the beam envelope undergoes several oscillations, and that the residual magnetic field at the cathode plays an important role in delaying the halo formation process 相似文献
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The spatial distribution of the electromagnetic field excited by a relativistic particle crossing the surface of a metal is
studied. It is shown that the field of the uniformly moving charge must also be taken into account during measurements at
distances comparable to the path length for formation of the radiation. Expressions describing the effect of the self-field
of the charge on the transition radiation field are derived.
Zh. Tekh. Fiz. 67, 89–93 (September 1997) 相似文献