合肥光源电子储存环束流闭轨的局部校正

 在合肥同步辐射装置运行过程中,发生储存环的束流轨道偏移。利用现有设备对束流闭轨的位置进行了多次测量和分析,利用测量数据计算得到校正铁强度与束流位置之间移动的响应矩阵。并利用最小二乘法计算得到三个校正铁的凸轨系数,用于束流闭轨的局部凸轨校正,取得了预期的效果。     

基于MATLAB的合肥光源储存环束流轨道校正系统

 闭轨畸变对合肥同步光源的束流质量产生负面影响，因此必须对闭轨畸变进行校正。本文介绍了基于MATLAB的合肥光源储存环束流轨道校正系统的工作原理、开发过程及测试结果。该系统由束流轨道测量系统、校正铁系统和控制系统组成，基于MATLAB开发的束流轨道校正程序运行于操作员界面工作站上。首先对获取的束流轨道数据进行分析和计算，然后通过控制系统改变校正铁电源的电流以改变校正铁磁场强度，从而实现轨道校正。测试结果表明：束流轨道的最大畸变由校正前的4.468 mm下降到校正后的0.299 mm；标准方差（SDEV）由校正前的2.986 mm下降到校正后的0.087 mm。该系统达到了设计目标。     

CSRm束流累积阶段闭轨校正系统设计

为测量兰州重离子加速器冷却储存环主环(CSRm)束流累积阶段的闭轨畸变并进行闭轨校正,开发了闭轨校正系统,该系统由轨道测量系统、闭轨控制系统和校正磁铁系统构成。轨道测量系统实现对束流轨道的实时监测;闭轨控制系统读取束流轨道信息,然后进行闭轨校正计算,并将计算后的校正值传输给校正磁铁系统;校正磁铁系统通过改变校正电源的值,改变校正磁铁的强度,实现对束流轨道的调整,完成闭轨校正。模拟测试结果表明,束流轨道水平方向的最大畸变由校正前的3.37 mm减小为校正后的0.39 mm,垂直方向的最大畸变由校正前的4.21 mm减小为校正后的0.31 mm。该系统能够实现响应矩阵的自动测量和束流轨道的自动校正,满足设计要求。     

合肥光源电子储存环束流闭轨的局部校正

在合肥同步辐射装置运行过程中，发生储存环的束流轨道偏移。利用现有设备对束流闭轨的位置进行了多次测量和分析，利用测量数据计算得到校正铁强度与束流位置之间移动的响应矩阵，并利用最小二乘法计算得到三个校正铁凸轨系数，用于束流闭轨的局部凸轨校正，取得了预期的效果。     

合肥光源束流闭轨局部调整和校正

 针对特定实验站调整光源点位置的要求,设计了合肥光源储存环束流闭轨局部调整和校正系统,介绍了该系统的工作原理、硬件组成、软件设计及运行结果,设计要求束流闭轨局部调整的最大幅度为1~2 mm,水平方向和垂直方向其余闭轨畸变均方根分别小于50和30 μm。校正系统采用轨道设定法作为束流闭轨局部调整和校正算法,由束流轨道测量系统、校正铁系统和控制系统组成。运行结果显示：水平和垂直方向分别调节2.0和1.5 mm,水平方向和垂直方向其余闭轨畸变均方根分别为45.14和27.62 μm。     

利用约束线性最小二乘法实现合肥光源束流闭轨全环校正和反馈

由于存在各种非理想因素,束流在储存环中的闭轨会发生畸变。对束流闭轨畸变进行校正的方法较多,目前合肥光源(HLS)采用奇异值分解(SVD)法进行束流闭轨的全环校正和反馈。针对SVD法不足之处,采用约束线性最小二乘法(CLLS)来改进HLS束流闭轨的全环校正和反馈。介绍了束流闭轨畸变校正的理论,着重介绍应用CLLS对HLS储存环束流闭轨畸变进行全环校正和反馈,并给出运行结果。结果显示,利用CLLS后,HLS敏感实验线站的束流轨道稳定性和重复性得到明显改善。     

CSRm闭轨畸变及其校正的模拟研究

在给定的磁铁安装误差和磁场加工误差的条件下,对兰州重离子加速器冷却储存环主环的闭轨畸变及其校正进行了计算机模拟研究,在典型的误差分布下,校正前的水平方向及垂直方向的最大闭轨畸变分别为3.08mm和2.73mm,校正模拟的结果显示CSRm的闭轨畸变可以控制在足够小的范围内.     

合肥同步辐射光源的耦合度校正

 在合肥同步辐射储存环中由于四极铁的旋转误差和在六极铁中垂直方向的闭轨畸变等,导致电子水平和垂直两个方向的运动的耦合,耦合度达到12%（测量值）。为降低束流的横向耦合度,提高光源亮度,拟在储存环中安装斜四极铁,探讨了斜四极铁的设计及安装的方法。     

DEPU对上海光源储存环的影响与补偿

上海光源储存环安装了一套由两台椭圆极化波荡器组成的插入件（DEPU）,该插入件尤其是其中一台椭圆极化波荡器的积分场误差引起了闭轨畸变、工作点漂移、耦合度变化、动力学孔径减小等多种效应,这些效应对上海光源储存环的正常运行造成了极大影响。采用校正线圈前馈将最大闭轨畸变降低到10 m的水平,采用四极铁强度前馈将工作点漂移控制在0.001左右,采用斜四极铁前馈将耦合度很好地控制在0.1%左右。通过六极铁在线优化解决了动力学孔径退化的问题,将注入效率保持在80%以上。在接近4年的运行中,补偿方案工作表现很好,轨道补偿的前馈还在不断地完善中。     

上海光源储存环线性模型校正

上海光源是我国刚刚建成的一台第三代中能同步辐射光源。为使得上海光源能够严格工作在设计状态下, 在调试过程中进行了一系列线性模型的校正, 主要包括闭轨校正、 基于束流准直（BBA）校正、 LOCO参数校正和线性耦合校正。经过反复的线性模型校正以后, 上海光源储存环的闭轨畸变均方根误差在水平和垂直两个方向可以分别控制到50和60 μm的水平, 包络函数畸变和色散函数畸变都可以控制到小于1%的状态, 工作点和束流发射度基本上校正到了设计值。线性耦合校正能够方便地将储存环的耦合度从0.02%调节到2%左右。调试结果表明, 上海光源采取的这一套线性模型校正方法, 能够有效地将上海光源的工作状态校正到设计状态, 并且为其他模式的调节奠定了基础。In the commissioning stage of Shanghai Synchrotron Radiation Facility(SSRF) storage ring, several methods were used to correct the linear optics. Beam Based Alignment(BBA) was used for BPM\|Quadrupole offsets measurement; Response matrix was used for orbit correction; LOCO was used for linear optics fitting, and quadrupoles strength were adjusted to correction the beta function; coupling was measured and corrected by skew quadrupoles. After correction, closed orbit are reduced to 50/60 μm in hortizontal and vertical plane; β beating and dispersion errors are less than 1%; betatron tune and emmittance are closed to the design value; betatron coupling also can be adjusted from 0.02% to 2%. These methods have been proved to be useful for storage ring calibrations, with the help of these methods, SSRF storage ring can be tuned to the design model and other model easily.     

HIAF-SRing的等时性模式光学设计

高精度环形谱仪SRing作为HIAF装置的核心之一,是获取高品质放射性次级束,并将束流用于加速器技术研究、原子物理及核物理实验的关键设备。SRing有三种运行模式:等时性模式、正常模式与内靶模式。等时性模式下,SRing运行在特殊线性光学设置下,可以精确测量寿命低至几十微秒的原子核的质量。介绍SRing等时性模式的线性光学及高阶项校正的设计方案。在使用程序GICOSY进行等时性高阶项校正数值计算后,将得到的光学传输矩阵输入到程序MOCADI进行粒子跟踪模拟。以γ_t=1.43的等时性模式为例,SRing的动量接收度为±0.20%,粒子跟踪结果显示,在仅满足一阶等时性条件时SRing的质量分辨能力R=1.6×104。在保证动量接收度不变的前提下,考虑了等时性高阶项校正后SRing的质量分辨能力提高到R=1.2×106,达到设计要求。The Spectrometer Ring, as the most important experiment terminal of the High Intensity heavy-ion Accelerator Facility (HIAF) project, is a key device to obtain high-quality radioactive ion beams (RIBs) for atomic physics, nuclear physics experiments and accelerator technology researches. Three operation modes including the isochronous mode, the normal mode and the internal target mode, have been designed for the SRing. In the isochronous mode, the SRing operates under a special ion optics and could be used for precision mass measurement of short-lived nuclei with half-life shorter than several tens of microseconds. This study aims to design the ion optics for the isochronous mode and improve the mass resolving power of the SRing with higher-order ion-optical correction scheme for isochronism while preserve a large momentum acceptance of SRing. The ion optics and the higher-order correction for the isochronous mode are calculated with the code MAD-X and GICOSY respectively. Three ion optics with γ_t=1.43, 1.67, 1.83 settings have been calculated. The code MCOADI which utilizes the matrixes generated by the code GICOSY is used for particles tracking to verify the correction results. For the ion-optical setting of γ_t=1.43 with a momentum acceptance of ±0.20%, the mass resolving power of the SRing could be improved from R=1.6×104 to R=1.2×106, after isochronous higher-order corrections.     

Analysis and correction of linear optics errors,and operational improvements in the Indus-2 storage ring

Estimation and correction of the optics errors in an operational storage ring is always vital to achieve the design performance. To achieve this task, the most suitable and widely used technique, called linear optics from closed orbit(LOCO) is used in almost all storage ring based synchrotron radiation sources. In this technique, based on the response matrix fit, errors in the quadrupole strengths, beam position monitor(BPM) gains, orbit corrector calibration factors etc. can be obtained. For correction of the optics, suitable changes in the quadrupole strengths can be applied through the driving currents of the quadrupole power supplies to achieve the desired optics. The LOCO code has been used at the Indus-2 storage ring for the first time. The estimation of linear beam optics errors and their correction to minimize the distortion of linear beam dynamical parameters by using the installed number of quadrupole power supplies is discussed. After the optics correction, the performance of the storage ring is improved in terms of better beam injection/accumulation, reduced beam loss during energy ramping, and improvement in beam lifetime. It is also useful in controlling the leakage in the orbit bump required for machine studies or for commissioning of new beamlines.     

BEPCⅡ LINAC束流光学匹配及轨道校正计算研究

 北京正负电子对撞机直线注入器(BEPCⅡ LINAC)的升级改进要求建立束流光学匹配计算和轨道校正系统，为此对束流光学匹配计算和轨道校正计算的方法进行了研究，并采用VC++语言编写了相应的程序，利用最小二乘法原理进行了束流光学匹配计算，模拟了束流轨道校正，取得了较为理想的结果。     

HIAF中环形质量谱仪SRing的线性设计

为了精确测量短寿命原子核质量,提出了在强流重离子加速器装置(HIAF)上建造高精度环形质量谱仪SRing。SRing长188.7 m,最大设计磁刚度为1 3 T·m,主要由磁聚焦结构、注入系统、引出系统、随机冷却以及探测系统等组成。SRing将运行在等时性模式和收集模式下用于短寿命原子核质量的精确测量和放射性次级束流收集并纯化。详细介绍了SRing的线性光学设计,并给出两种模式下的光学设计、注入及引出系统的设计等,设计参数优化完毕后,机器测量精度有望提高到10~6。     

Orbit response matrix analysis and lattice periodicity restoration of the SSRF storage ring

In this paper, we present numerically and experimentally the linear beam-optics distortion in the SSRF storage ring and the correction of optics by using a number of quadrupole magnets installed in the storage ring. The measured orbit-response matrices were fitted to the model-response matrices to obtain the β and the dispersion functions in the storage ring. By readjusting the currents of quadrupole-magnet power supplies, we were able to successfully restore the optics parameters to values very close to the design ones, with rms deviations around 1%. This periodicity restoration is verified with the β function measurement.     

A GUI tool for beta function measurement using MATLAB

The beta function measurement is used to detect the shift in the betatron tune as the strength of an individual quadrupole magnet is varied. A GUI (graphic user interface) tool for the beta function measurement is developed using the MATLAB program language in the Linux environment, which facilitates the commissioning of the Shanghai Synchrotron Radiation Facility (SSRF) storage ring. In this paper, we describe the design of the application and give some measuring results and discussions about the definition of the measurement. The program has been optimized to solve some restrictions of the AT tracking code. After the correction with LOCO (linear optics from closed orbits), the horizontal and the vertical root mean square values (rms values) can be reduced to 0.12 and 0.10.     

Design and first commissioning of a new mode with lower emittance in the SSRF storage ring

A new mode is designed with an emittance of 2.47 nm-rad at 3.0 GeV beam energy, lower than the nominal mode of the Shanghai Synchrotron Radiation Facility (SSRF) storage ring. Details of the linear optics design and the nonlinear optimization are presented in this paper. During Phase I commissioning of the storage ring we tested the new optics mode and some expected results were obtained. After restoring the linear optics by means of the linear optics with closed orbit technique, the main parameters of the real machine agree well with the designed values and the injection efficiency and beam lifetime are acceptable.