直通道磁元件磁场测量

为使重离子束从注入器（ＳＦＣ）不经主加速器（ＳＳＣ）直接传输到实验终端。最近在兰州重离子研究装置（ＨＩＲＦＬ）上新建了直通管道系统。在该系统中有３台偏转磁铁和３台四极透镜。本文叙述了它们的测磁内容和方法，给出了激磁曲线、径向和轴向场分布、磁场梯度、等效长度等结果。结果表明：全部符合原设计要求，并有一定的余量。     

脉冲四极磁铁峰值梯度测量

一、测量原理质子直线加速器中的漂移管四极透镜是由近似半正弦波的脉冲电流励磁的。脉冲底宽约为3.5毫秒,重复频率为每秒10次。四极透镜孔径内的磁场,若只考虑其空间分布,它是中心为零的梯度场,如图1所示。图中B_y、B_x分别表示磁场在y和x方向的分量。     

中国散裂中子源快周期同步加速器磁铁电源系统的研究

目前正在进行可行性研究的中国散裂中子源的主体结构是1台强流质子同步加速器。该加速器的一期目标为注入能量70MeV、引出能量1.6GeV、束流功率100kW、循环工作频率25Hz。文章阐述系统总体结构的设计原则以及二极磁铁（B）和四极磁铁（Q）磁场的跟踪误差要求。     

一种基于伸展线法的小孔径四极磁铁测量方法

针对目前多极磁铁孔径越来越小的发展趋势，搭建了一种基于单根伸展线法(Single Stretched Wire Method,SSWM)的磁测系统，该系统的主要优势是测量域所需空间小且运动模式灵活。基于该系统的优势及四极磁铁磁场分布的特点，尝试使用双曲线轨迹对四极磁铁靠近其四个极头的区域进行了扫描测量，并根据矢势在测量点分布的特性，提出了一种全新的数据分析方法，用以分析四极磁铁的梯度积分和高阶场误差。用该系统对一孔半径为11 mm、梯度大于100 T·m^-1的四极磁铁进行测量，测量结果表明高阶场误差测量重复性好于±1.5×10^-4，能满足小孔径高梯度四极磁铁的磁场测量要求。     

海关集装箱检测用电子直线加速器聚焦线圈磁场设计与测试

介绍了在电子直线加速器粒子动力学基础上进行聚焦线圈轴向磁场的设计；利用ＬＩＮＥ－ＡＣＣ／ＰＣ程序模拟计算，给出了不同初始发射度情况下满足束流包络要求的各种聚焦磁场数据。对已经加工好的聚焦系统进行了磁场分布测量，并将实际磁场与理论计算进行了比较。上述工作为确定聚焦线圈的设计方案和加速器的出束实验提供了可靠、丰富的数据。     

海关集装箱检测用电子直线加速器聚集线圈磁场设计与测试

介绍了在电子直线加速器粒子动力学基础上进行聚集线圈轴向磁场的设计；利用ＬＩＮＥ－ＡＣＣ／ＰＣ程序模拟计算，给出了不同初始发射度情况下满足束流包络要求的各种聚焦磁场数据。对已经加工好的聚焦系统进行了磁场分布测量，并将实际磁场与理论计算进行了比较。上述工作为确定聚焦线圈的设计方案和加速器的出束实验提供了可靠、丰富的数据。     

CYCIAE-30医用回旋加速器束流输运系统升级改造

在中国原子能科学研究院CYCIAE－30医用回旋加速器现有的束流输运系统的基础上，根据气体靶生产新品种医用同位素的技术要求，用TRACE－3D对束流输运系统的升级改造方案进行设计，包括束流线的总体布局和光学设计。根据束流光学设计的结果，〖JP3〗设计了新增束流线的磁四极透镜和偏转磁铁。     

BRISOL谱仪关键技术研究

HI-13串列加速器升级工程在线同位素分离器（BRISOL）需对同质异位素进行分辨,谱仪设计质量分辨率为20 000,是很高的技术指标,对离子源、高压、分析磁铁、四极透镜等设备均有很大的挑战。本文详细介绍了BRISOL谱仪关键技术及其测试结果。能散对谱仪的质量分辨率影响较大,BRISOL谱仪设计采用异能大小铁结构消除能量色散。离子源采用表面离子源,并采用三电极引出系统,中间电极电压可调用以优化束流品质,优化后离子束RMS发射度好于3.8 πmm•mrad。分析磁铁采用表面线圈进行磁场垫补,垫补后积分场均匀性好于3.5×10^-5。为修正像差,大分析磁铁安装了β线圈和γ线圈,同时,在分析磁铁前后共设置了4台电六极透镜。     

加速器-电镜联机的离子光路及其调整方案

离子辐照引起的材料微结构变化是一个复杂的过程,用加速器-电镜联机装置可原位观察载能离子束辐照引起的材料微结构演变.武汉大学加速器-电镜联机装置由1台2×1.7 MV串列加速器、1台200 kV离子注入机和1台200 kV透射电镜组成,通过自行设计的传输系统实现联机.本文介绍联机装置的光路布局,给出了静电加速器离子动力学计算程序LEADS(linear and electrostatic accelerator dynamics simulation)优化计算的结果,提出了两种改进方案,并用LEADS对改造后的加速器-电镜联机中离子运动进行了计算.结果显示,调整现光路二单元四极透镜的同时,在200 kV注入机90°偏转磁铁至电镜之间增加1个二单元静电四极透镜,将提高该系统中离子束传输效率.     

100MeV强流质子回旋加速器中心区磁场和电场轴向聚焦的研究

在回旋加速器中心区的设计中，轴向运动关心的主要问题和径向运动非常不同。这基本上源于在回旋加速器中心处轴向聚焦频率几乎为零的事实，然而径向振荡频率值约为1。回旋加速器中，在起始的几圈内等时性磁场提供的轴向聚焦接近于0，为加强磁场聚焦在等时场上设计一小的凸起磁场，可提供正的磁场梯度即轴向聚焦，属于弱聚焦，且该磁场带来的另一不利的效应是造成滑相。     

方位投影的研究

传统的方位投影技术,已在铀矿地质勘查、储量计算图件绘制中应用。近年来,随着全球卫星定位系统(GPS)在铀矿地质勘测中的应用,对地质图的数学基础方面提出了新的要求。文章在透视方位投影的基础上,应用归纳方法,提出方位投影的一个概略公式。应用该公式,几乎可以包括目前所有的方位投影,而且可以应用于探求任意性质的方位投影。更重要的是应用该概括公式,便于对各种方位投影的计算以及不同性质方位投影间的坐标变换。同时对球心投影的性质进行研究得出球面上任何大圆在球心投影中均投影成直线。球面上共焦双曲线在球心投影中仍投影成共焦双曲线。球面上共焦点之椭圆、双曲线,在球心投影中仍投影成共焦椭圆、双曲线。据此,可以把解算球面上大圆、椭圆和双曲线等几何问题,归结为解算平面上的直线、椭圆和双曲线问题,使实际应用大为简化。     

Simulation of a low energy beam transport line

A 2.45 GHz electron cyclotron resonance intense proton source and a low energy beam transport line with dual-Glaser lens were designed and fabricated by Institute of Modern Physics for a compact pulsed hadron source at Tsinghua. The intense proton beams extracted from the ion source are transported through the transport line to match the downstream radio frequency quadrupole accelerator. Particle-in-cell code BEAMPATH was used to carry out the beam transport simulations and optimize the magnetic field structures of the transport line. Emittance growth due to space charge and spherical aberrations of the Glaser lens were studied in both theory and simulation. The results show that narrow beam has smaller aberrations and better beam quality through the transport line. To better match the radio frequency quadrupole accelerator, a shorter transport line is desired with sufficient space charge neutralization.     

Research on Quadrupoles Along Injection Line for CRM Cyclotron of CYCIAE-100

在强流加速器及其传输线上空间电荷效应对束流会产生重要影响。随着加速器计算物理的发展和计算机运算能力的迅速提升，PIC（Particle—In—Cell）方法已广泛应用于数值模拟强流束在加速器及传输线中运动规律。     

Analysis of the fringe field region of magnetic quadrupole lenses: field measurements and ion optical calculations

An investigation into the minimisation of the duodecapole fringe field components of magnetic quadrupole lenses has been conducted at Melbourne. As part of this program, a detailed field mapping of the fringe field region of the Melbourne magnetic quadrupole lenses has been conducted (G.R. Moloney, D.N. Jamieson and G.J.F. Legge, Nucl. Instr. and Meth. B 54 (1991) 24). The field mapping technique measures the radial magnetic field component, B_r over the three cylindrical coordinates, r, and z. We have also conducted a program of modifying the pole tip termination of the lenses to reduce the duodecapole field components. Complete magnetic field measurements for the modified lens pole tips have been presented previously (G.R. Moloney, D.N. Jamieson and G.J.F. Legge, Nucl. Instr. and Meth. B 77 (1993) 35–38). This paper presents an Ion Optical analysis of the effects of the fringe field components on the beam optics of the Melbourne Microprobe systems. The optical effects are calculated with a new computer code developed at Melbourne. Standard numerical ray tracing is performed utilising Runge-Kutta techniques.     

谐波垫补原理及其在加速器常规磁铁设计与磁场垫补中的应用

加速器常规磁铁磁场质量评估通常表示为工作气隙好场区内高阶磁场占主磁场的相对含量,它通常要求在10^-4量级内。这些高阶磁场来源于磁极的有限长度与宽度和极面设计参数选择产生的若干过大的系统高阶磁场偏差及加工与材料的不理想等因素产生的若干过大的随机高阶磁场偏差。这些偏差均会导致磁场质量变坏。谐波垫补法针对每个过大的高阶磁场利用磁极形位改变对磁场的扰动效应产生一与现存过大高阶磁场大小相当但符号相反的高阶磁场,用来抵消现存的过大的高阶磁场,达到根本改善磁场质量的目的。本文分析了谐波垫补原理,并具体分析了它们在二极磁铁和四极磁铁设计与磁场垫补中的应用。     

Analytical expression for the Mössbauer line shape of 57Fe in the presence of mixed hyperfine interactions

A new method is presented for the calculation of Mössbauer line shapes of hyperfine split nuclei. Instead of solving explicitly the hyperfine Hamiltonian for its eigenvalues and eigenvectors this method uses a superoperator formalism to yield closed form expressions for the Mössbauer line shape in the presence of magnetic dipole and electric quadrupole hyperfine interactions. The advantage of this method over the conventional one lies in the fact that averages over hyperfine field orientations may be calculated analytically. This is demonstrated for the case of ⁵⁷Fe with randomly oriented electric field gradients in a uniform oriented magnetic field.     

Electric quadrupole transition probabilities and line strengths of Ti

Electric quadrupole transition probabilities and line strengths have been calculated using the weakest bound electron potential model for sodium-like titanium, considering many transition arrays. We employed numerical Coulomb approximation and non-relativistic Hartree–Fock wavefunctions for the expectation values of radii in determination of parameters of the model. The necessary energy values have been taken from experimental data in the literature. The calculated electric quadrupole line strengths have been compared with available data in the literature and good agreement has been obtained. Moreover, some electric quadrupole transition probability and line strength values not existing in the literature for some highly excited levels have been obtained using this method.     

Field reconstruction technique for testing magnetic quadrupole lenses

A number of analytical instruments make use of strong magnetic quadruple lenses. Performance properties of such instruments are determined by the presence of lens aberrations that arise from the structure of the lens magnetic field. This paper describes a technique for reconstruction and analysis of the 3-D field of the magnetic quadrupole lens. Measurements of the radial B_r or longitudinal B_z component of the field are used as boundary conditions for the Laplace equation for magnetic scalar potential. Application of the charged density method for the solution of the boundary-value problem allows the field and its multipole components to be determined to a high accuracy. The field reconstruction technique can be used for determination of both intrinsic and parasitic multipole components of the field in a magnetic quadrupole lens. This technique is suitable either for a single magnetic multipole lens or for a magnetic multipole lens system.     

Optimization of the working distance of an ion microprobe-forming system

A high-resolution ion microprobe necessitates the use of a small working distance (the distance from the final quadrupole lens of a probe-forming system to the specimen) in order to produce a large demagnification. But at the same time a small working distance is a source of a number of practical difficulties. We have presented an approach for determining a working distance that provides the best spatial resolution with the main practical limitations taken into account. We used a probe-forming system acceptance as a criterion of optimality. The calculations have revealed the existence of an optimal working distance in a set of common probe-forming systems, but it can be achieved only after changing of a design of a final quadrupole lens. We proposed a possible design of conic lens that allows solving the problem of detectors location and creating a short focus system. Three-dimensional calculations of magnetic field within this lens predicted a good quality of field structure.