周期聚焦磁场中束晕-混沌的简单函数控制

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．     

周期聚焦磁场中束晕-混沌的实Morlet小波函数控制

 基于束晕-混沌的非线性控制策略,对周期性聚焦磁场中初始分布满足K-V分布的粒子束进行模拟研究,提出了控制其束晕-混沌的实Morlet小波函数控制器,并给出具体的实施方案。数值模拟研究表明,在适当的参数条件下,运用这种方法不仅可以消除束晕及其再生现象,达到对束晕-混沌的有效控制,而且可以控制束流到均匀分布。     

强流束晕-混沌的外部磁场开关控制

研究了强流离子束在周期聚焦磁场通道中束晕-混沌的外部磁场开关参数控制方法. 将该方法应用在多粒子模型中，实现了对5种不同初始分布质子束的束晕-混沌的有效控制，得到了消除束晕及其再生现象的理想结果.在强流加速器系统中，由于外部磁场是可测和可调 的物理量，因此该控制方法有利于实验研究，可为强流质子加速器中周期聚焦磁场的设计和实验提供参考. 关键词： 强流离子束 周期聚焦磁场通道 束晕_混沌 混沌控制 开 关控制     

强流束晕-混沌的外部磁场自适应控制

研究了强流质子束在周期聚焦磁场通道中束晕 混沌的外部磁场自适应控制方法,给出了磁场控制方程。将该方法应用在多粒子模型中,实现了对4种不同初始分布质子束的束晕 混沌的有效控制,得到了消除束晕及其再生现象的理想结果。在强流加速器系统中,由于外部磁场是可测和可调的物理量,因此该控制方法有利于实验研究,可为强流质子加速器中周期聚焦磁场的设计和实验提供参考。     

强流束晕-混沌的外部磁场自适应控制

 研究了强流质子束在周期聚焦磁场通道中束晕 混沌的外部磁场自适应控制方法,给出了磁场控制方程。将该方法应用在多粒子模型中,实现了对4种不同初始分布质子束的束晕 混沌的有效控制,得到了消除束晕及其再生现象的理想结果。在强流加速器系统中,由于外部磁场是可测和可调的物理量,因此该控制方法有利于实验研究,可为强流质子加速器中周期聚焦磁场的设计和实验提供参考。     

强流束晕-混沌的外部磁场滑模变结构控制

 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。     

束晕-混沌的神经网络自适应控制

理论分析了强流离子束在周期磁场聚焦通道中传输时产生的束晕 混沌动力学行为,给出了近似反映实际聚焦磁场的余弦函数形式。然后利用神经网络方法对非线性复杂系统控制的优越性,提出前馈反传神经网络方法对强流离子束中束晕 混沌进行自适应控制。通过适当选择的神经网络控制结构和线性反馈系数以及自适应调整神经网络的权系数,可将强流离子束的包络半径达到束匹配半径的控制目标,且束包络的抖动大小明显减少,束晕 混沌现象得到了明显的抑制。     

束晕-混沌的神经网络自适应控制

 理论分析了强流离子束在周期磁场聚焦通道中传输时产生的束晕 混沌动力学行为,给出了近似反映实际聚焦磁场的余弦函数形式。然后利用神经网络方法对非线性复杂系统控制的优越性,提出前馈反传神经网络方法对强流离子束中束晕 混沌进行自适应控制。通过适当选择的神经网络控制结构和线性反馈系数以及自适应调整神经网络的权系数,可将强流离子束的包络半径达到束匹配半径的控制目标,且束包络的抖动大小明显减少,束晕 混沌现象得到了明显的抑制。     

一种基于聚焦磁场改变的束晕-混沌控制研究

采用了加速器中周期性磁场聚焦强度形式为与实际相近的正弦函数形式 ,运用多粒子模拟程序 (PIC)进行模拟研究 ,用小波函数控制方法实现了束晕 -混沌有效控制。     

强流加速器中束晕-混沌的小波间隔反馈控制

在束晕-混沌的小波函数控制已实现的基础上,给出了一种形式更为简单的小波函数控制器,并研究了束晕混沌的多周期间隔反馈控制方法.以控制初始条件遵从Kapchinshij-Vladimirskij分布的离子束为例进行模拟,结果表明,通过适当选择间隔的周期数和小波控制器的控制参数,仍能很有效地对束晕混沌进行控制,并能达到消除束晕及其再生现象的理想结果.研究结果可望为实用强流加速器的研制提供有价值的参考 关键词： 小波函数控制器 多周期间隔 束晕-混沌 强流离子束     

Control of Beam Halo-Chaos for an Intense Charged-Particle Beam Propagating Through Double Periodic Focusing Field by Soliton

We study an intense beam propagating through the double periodic focusing channel by the particle-core model, and obtain the beam envelope equation. According to the Poincare-Lyapunov theorem, we analyze the stability of beam envelope equation and find the beam halo. The soliton control method for controlling the beam halo-chaos is put forward based on mechanism of halo formation and strategy of controlling beam halo-chaos, and we also prove the validity of the control method, and furthermore, the feasible experimental project is given. We perform multiparticle simulation to control the halo by using the soliton controller. It is shown that our control method is effective. We also find the radial ion density changes when the ion beam is in the channel, not only the halo-chaos and its regeneration can be eliminated by using the nonlinear control method, but also the density uniformity can be found at beam＇s centre as long as an appropriate control method is chosen.     

Control of beam halo-chaos by sample function

The K-V beam through an axisymmetric uniform-focusing channel is studied using the particle--core model. The beam halo-chaos is found, and a sample function controller is proposed based on mechanism of halo formation and strategy of controlling halo-chaos. We perform multiparticle simulation to control the halo by using the sample function controller. The numerical results show that our control method is effective. We also find that the radial ion density changes when the ion beam is in the channel: not only can the halo-chaos and its regeneration be eliminated by using the sample function control method, but also the density uniformity can be found at the beam's centre as long as an appropriate control method is chosen.     

Control of Beam Halo-Chaos by Fraction Power-Law Function in Hackle Periodic-Focusing Channel

The Kapchinsky Vladimirsky （K-V） beam through a hackle periodic-focusing magnetic field is studied using the particle-core model. The beam halo-chaos is found, and an idea of fraction power-law function controller is proposed based on the mechanism of halo formation and the strategy of controlling halo-chaos. The method is applied to the multi-particle simulation to control the halo. The numerical results show that the halo-chaos and its regeneration can be eliminated effectively by using the fraction power-law function control method. At the same time, the radial particle density is uniform at the beam＇s center as long as the control method and appropriate parameter are chosen.     

Stability Analysis of Some Nonlinear Feedback Control Methods for Beam Halo-Chaos Suppression

Control of beam halo-chaos has been a very challenging subject for research in recent years, in which some nonlinear feedback methods have been developed for suppression of beam halo-chaos in high-current proton linear accelerators. However, stability analysis of such successful nonlinear feedback control methods has not yet been rigorously carried out, which remains an important open topic in the field. In this letter, we present a rigorous mathematical analysis of several nonlinear feedback control methods that are applied to control beam halo-chaos with great success on simulations.     

Nonlinear Control of Beam Halo-Chaos in Accelerator-Driven Clean Nuclear Power System

Beam halo-chaos in high-current accelerators has become a key concerned issue because it can cause excessive radioactivity from the accelerators therefore significantly limits their applications in industry, medicine, and national defense. Some general engineering methods for chaos control have been developed in recent years, but they generally are unsuccessful for beam halo-chaos suppression due to many technical constraints. Beam halo-chaos is essentially a spatiotemporal chaotic motion within a high power proton accelerator. In this paper, some efficient nonlinear control methods, including wavelet function feedback control as a special nonlinear control method, are proposed for controlling beam halo-chaos under five kinds of the initial proton beam distributions (i.e., Kapchinsky-Vladimirsky, full Gauss,3-sigma Gauss, water-bag, and parabola distributions) respectively. Particles-in-cell simulations show that after control of beam halo-chaos, the beam halo strength factor is reduced to zero, and other statistical physical quantities of beam halo-chaos are doubly reduced. The methods we developed is very effective for suppression of proton beam halo-chaos in a periodic focusing channel of accelerator. Some potential application of the beam halo-chaos control in experiments is finally pointed out.     

非线性反馈控制强流加速器中的束晕—混沌现象

 基于Poincare-Lyapunov定理, 应用定性分析,提出用非线性反馈法实现对束晕-混沌的控制。矩阵传输理论研究已发现：质子束的空间电荷效应导致质子束径向发散及束晕现象。因此, 构造一类正弦等形式的非线性反馈函数去抵消质子束空间电荷非线性效应。PIC数值模拟结果证实该方法的可行性,为实验提供一定理论依据。     

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.