强流离子注入机加速管的聚焦特性研究

 讨论了三间隙强流离子加速管的聚焦特性，计算了各种能量下离子束聚焦情况，并分析了抑制空间电荷效应所需要的电场强度。最后总结了三间隙加速管设计和调试应注意的问题。     

RF离子源引出特性的研究

 为了使RF离子源具有良好的引出特性，测试了吸极几何参数、振荡器板压和引出电压对离子源聚焦度的影响，对实验结果进行了分析。在其它参数不变的情况下，吸极的外径D与内径d之比存在最佳值，增加D/d，有利于过聚焦的离子束恢复聚焦状态。吸极的长度为L，石英套管比吸极长l。当l/D增大时，聚焦度上升，引出束流下降。L/d之比减小时，聚焦度增大。当L/d小于4时，聚焦度增加趋势变缓。综合考虑聚焦度、引出束流和气压，D/d，l/D，L/d适宜的选择范围分别为1.6～2.1，0.7～1.1,4～7。增加振荡器功率会使离子束呈弱聚焦，而增加引出电压会使离子束呈过聚焦。振荡器功率和引出电压都存在最佳值。     

Acceleration and focusing of intense ion beams in rf undulator structures

Bunching, acceleration, and transverse focusing of intense ion beams in an undulator linac are considered. Such an accelerator features the absence of an rf field harmonic synchronous with the beam. A 3D equation of motion in the Hamiltonian form is derived in the smooth approximation, and the general conditions for ion beam acceleration and transverse focusing in the undulator linac are formulated. Basic analytical results are compared with the results of numerical simulation of the beam dynamics in the polyharmonic field of an accelerating cavity.     

Controlling beam halo-chaos via backstepping design

A backstepping control method is proposed for controlling beam halo-chaos in the periodic focusing channels （PFCs） of high-current ion accelerator. The analysis and numerical results show that the method, via adjusting an exterior magnetic field, is effective to control beam halo chaos with five types of initial distribution ion beams, all statistical quantities of the beam halo-chaos are largely reduced, and the uniformity of ion beam is improved. This control method has an important value of application, for the exterior magnetic field can be easily adjusted in the periodical magnetic focusing channels in experiment.     

菲涅尔波带片对高斯光束的变换

从波带片的特性出发研究高斯光束通过波带片的聚焦特性。用失调望远系统的失调量变化调节出射光束聚焦点的位置，并对聚焦点的变化范围和光斑大小进行描述，最后对波带片对高斯光束聚焦特性进行评价。     

Beam focusing in a linear ion accelerator consisting of a periodic sequence of independently phased superconducting cavities

Focusing of a low-energy beam of heavy ions in a linear accelerator based on a periodic sequence of independently phased superconducting cavities is considered. The possibility of heavy ion beam focusing by a system of superconducting solenoids is analyzed. The advantages and disadvantages of this focusing technique are considered. It is shown that solenoids with a magnetic field exceeding B = 15 T are required for focusing ion beams with a small charge-to-mass ratio Z/A ≈ 1/66 in a superconducting accelerator.     

Stability and transport properties of an intense ion beam propagating through an alternating-gradient focusing lattice

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.     

强流ECR离子源引出系统研究

为了提高强流ECR 离子源的引出束流品质,分别设计了1# 和2# 引出系统,利用束流引出模拟软件PBGUNS 对1# 和2# 引出系统进行了质子束流引出与传输的模拟计算,结合实际测得的发射度数据分析引出系统,发现2# 引出系统比1# 引出系统引出束流品质高。对ECR 离子源引出系统的电势等位线分布等参数引起的球差进行了简单数学推导及MATLAB 绘图,并结合1# 和2# 引出系统束流相图模拟结果证明了球差会使引出束流品质有效发射度增长,通过适当加大电极孔径可改善束流聚焦情况,得到了束流光学聚焦较好的束流引出系统设计。To improve the quality of extracted ion beam from a high current ECR ion source, 1# and 2# extraction systems were designed and tested. The PBGUNS code was used to simulate the 1# and 2# extraction systems of proton ion beam. The emittance measurement results with the two different extraction systems were compared and analyzed with the simulation, the conclusion that more high quality beam extracted from 2# system than 1# system was got. The formula derivation of ECR ion source extraction system spherical aberration and MATLAB drawing was done by the analyzing on the distribution of extraction field equipotentials, effective emittance increasing caused by spherical berration was proved by 1# and 2# extraction systems beam phase space simulation result, beam focusing would be improved if electrode hole size increasing appropriately and a general concept on good optics focusing of ion beam extraction system was proposed finally.     

聚焦慢速高荷态重离子束微束斑X射线源

利用电子束离子源(EBIS)或者电子束离子陷阱(EBIT)产生的慢速高电荷态重离子束轰击金属靶面,离子束与靶面作用并复合辐射特征X射线;并将高荷态离子束采用离子光学系统会聚为微细束后再与靶面作用,能够辐射出微米甚至亚微米级、纳米级的微束斑X射线.本文介绍这一新型微束斑X射线源的结构、机理及其特性等.     

Study of the aberrations of the IMP heavy ion microbeam irradiation system

A high energy heavy ion microbeam irradiation system is constructed at the Institute of Modern Physics (IMP) of the Chinese Academy of Sciences (CAS). A quadrupole focusing system, in combination with a series of slits, has been designed here. The IMP microbeam system is described in detail. The     

Beam Dynamics Simulation in the LINAC-100 Accelerator Driver for the DERICA Project

The results of uranium ion beam dynamics simulation in front-end and superconducting sections of the accelerator-driver LINAC-100 for the new rare isotope facility DERICA (JINR, Dubna) are presented. The optimum parameters are chosen for the buncher accelerator with radiofrequency quadrupole focusing (RFQ) for uranium ion beam acceleration from the ion source up to the energy of 570 keV/nucleon. LINAC-100 modular superconducting part layout for uranium beam acceleration from 3 to 100 MeV/nucleon is obtained. The energies for the stripper section installation are chosen.

     

Simulation of ion beam extraction and focusing system

The characteristics of ion beam extraction and focused to a volume as small as possible were investigated with the aid of computer code SIMION 3D version 7. This has been used to evaluate the extraction characteristics (accel-decel system) to generate an ion beam with low beam emittance and high brightness. The simulation process can provide a good study for optimizing the extraction and focusing system of the ion beam without any losses and transported to the required target. Also, a study of a simulation model for the extraction system of the ion source was used to describe the possible plasma boundary curvatures during the ion extraction that may be affected by the change in an extraction potential with a constant plasma density meniscus.     

速调管离子噪声特性的模拟分析

 离子噪声已成为影响现代微波管性能的一个重要因素，采用一维混合模型研究了速调管的离子噪声，用自编的1维粒子模拟程序对速调管的离子噪声特性进行了分析。采用小信号近似，从理论上推导出了速调管离子噪声与相位畸变关系的表达式，表明微波管相位噪声直接来源于管内离子量的变化。模拟了有离子噪声时速调管的相位特性，对模拟过程做了离子诊断并与实验结果进行比较，证明了模拟过程的正确性。探讨了电子束电流、电压以及聚焦磁场对离子噪声的影响规律，束电流与束电压改变后，离子噪声的周期与大小相应改变，增大束电流，离子噪声幅度会下降，并趋于稳定，而在束电流不变的情况下，离子噪声存在一个最小值。束电流与束电压确定，存在最佳的磁场使离子噪声幅度最小。     

Study of the aberrations of the IMP heavy ion microbeam irradiation system

A high energy heavy ion microbeam irradiation system is constructed at the Institute of Modern Physics (IMP) of the Chinese Academy of Sciences (CAS). A quadrupole focusing system, in combination with a series of slits, has been designed here. The IMP microbeam system is described in detail. The intrinsic and parasitic aberrations associated with the magnets are simulated. The ion beam optics of this microbeam system is investigated systematically. Then the optimized initial beam parameters are given for high spatial resolution and high hitting rates.     

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。     

Focusing dynamics of high-energy density, laser-driven ion beams

The dynamics of the focusing of laser-driven ion beams produced from concave solid targets was studied. Most of the ion beam energy is observed to converge at the center of the cylindrical targets with a spot diameter of 30 μm, which can be very beneficial for applications requiring high beam energy densities. Also, unbalanced laser irradiation does not compromise the focusability of the beam. However, significant filamentation occurs during the focusing, potentially limiting the localization of the energy deposition region by these beams at focus. These effects could impact the applicability of such high-energy density beams for applications, e.g., in proton-driven fast ignition.     

Simulation of ion beam extraction and focusing system

The characteristics of ion beam extraction and focused to a volume as small as possible were investigated with the aid of computer code SIMION 3D version 7.This has been used to evaluate the extraction characteristics(accel-decel system)to generate an ion beam with low beam emittance and high brightness.The simulation process can provide a good study for optimizing the extraction and focusing system of the ion beam without any losses and transported to the required target.Also,a study of a simulation model for the extraction system of the ion source was used to describe the possible plasma boundary curvatures during the ion extraction that may be affected by the change in an extraction potential with a constant plasma density meniscus.     

Simulation of ion-optical systems for mass spectrometers with a quadrupole mass filter

Ion-optical systems with intermediate focusing and parallel extraction of the ion beam are simulated. The systems may be integrated with a quadrupole mass filter in order to improve the analytical properties of the latter.     

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.     

紧凑针孔中性粒子分析器标定系统的设计和研制

介绍了紧凑针孔中性粒子分析器(CP-NPA)标定系统,包括一套高能量、小流强的中性粒子束线源和一 个配套旋转平台。束线源由高频离子源、电单透镜、速度选择器、加速管、电四极透镜和中性化室组成。高频离 子源已经完成研制,并顺利建立起等离子体。单透镜已经完成仿真、制造和测试。实验中引出电压为 1.0kV 时, 调整单透镜聚焦电压最高可以引出 36.4μA 束流。速度选择器、加速管、聚焦电四极透镜和中性化室也已完成概念 /工程设计。