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。     

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。     

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。     

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。     

升级的合肥光源闭轨测量系统及其应用

 描述了合肥同步辐射光源二期工程中，电子储存环升级的闭轨测量系统及其在设备研制中的应用。介绍了性能稳定可靠的Bergoz束流位置监测电子学信号处理器。升级后的闭轨测量系统中处理电子学电路的束流位置分辨率可达1μm，系统误差小于10μm。整个测试系统的分辨率小于3μm。利用该高精度闭轨测量系统和基于束流准直系统完成了束流准直四极铁磁中心的测量，并和控制系统完成了储存环全环闭轨反馈校正试验。一个完整的束流位置监测系统已投入了在线运行，保障了为用户提供高稳定高品质的光源。     

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。     

高精度环形谱仪等时性模式的闭轨校正模拟

高精度环形谱仪（SRing）是HIAF装置的重要组成部分,闭轨校正设计是该同步加速器设计的关键部分。由于等时性模式（γ_t=1.43）线性光学水平β函数很大,磁铁场误差及安装误差会引起较大的闭轨畸变,并导致线性光学发生变化。模拟过程采用奇异值分解（SVD）算法,通过多次计算响应矩阵并计算校正铁校正量实现闭轨校正。同时考虑BPM误差的影响,并通过减少特征值使用个数降低校正铁校正量。校正后全环最大闭轨小于0.8 mm,线性光学也得到明显优化。     

CSR电子冷却段磁场造成闭轨畸变及校正

电子冷却的应用提高了重离子储存环的束流品质, 也为重离子储存环的运行带来了新的课题. 电子冷却段的横向磁场在引导约束强流电子束的同时也不可避免影响了多次经过的离子轨道. 为了保证束流的安全运行, 必须将离子轨道的畸变部分限制在局部范围, 并保证轨道畸变量对储存环接收度的影响可以容忍. 讨论在建的兰州重离子储存环HIRFL-CSR电子冷却段磁场及其造成闭轨畸变和校正方案.     

响应矩阵分析方法在BEPC储存环上的应用

由于储存环中各种元件误差的存在, 机器的实际运行模式与设计模式有一定的偏差. 目前广泛开展的响应矩阵方法研究, 可以分析出磁铁元件以及束流位置测量元件的误差, 使束流基本参数得到校正. 介绍了用响应矩阵分析方法, 在BEPC储存环上进行的局部轨道校正的实验研究, 以及BEPC储存环束流参数校正的模拟研究.     

Preliminary Study on Measurement of Magnetic Center of Quadrupoles Using Quadrupole Shunt for Hefei Storage Ring

The theoretical analysis of the DC K-modulation of quadrupole for the beam-based alignment method is presented. It is shown that the shift of the orbit,when the focussing strength of one quadrupole magnet is changed,can be described by the perturbed or unperturbed linear lattice parameters. The beam-based alignment system is constructed using DC K-modulation of quadrupole. In order to use the beam-based alignment method one must be able to individually adjust the strength of the quadrupole magnet. So,a switchable shunt resistor is installed on quadrupole to bypass 1%-2.5% magnet current and some solid-state relays are used to switch the shunt resistor in this beam-based alignment system. To improve the measurement accuracy,two methods are used. First method is that beam positions in measured quadrupole magnet are moved by local bump of beam closed orbit using the corrector magnets. Second method is that the root-mean-square of difference in closed orbit is fitted by a parabola function. The system can be not only used to position the beam in the magnetic center of quadrupoles,but also to measure the β function in quadrupole magnets. Some preliminary measurement results are given for Hefei 800MeV electron storage ring. These experimental results show that this system is valid to position the beam to the center of the quadrupole magnets and measure the β function at Hefei Light Source.     

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.     

电子储存环中闭合轨道和色散函数的校正

电子储存环中,由磁铁元件制造误差和安装误差导致的闭合轨道和色散函数的畸变,通常会引起一系列的负面效应,介绍了以合肥光源储存环为模型,用响应矩阵的奇值分解法对闭合轨道和色散函数进行校正的可行性研究结果.     

Beam based alignment of the SSRF storage ring

There are 140 beam position monitors (BPMs) in the Shanghai Synchrotron Radiation Facility (SSRF) storage ring used for measuring the closed orbit. As the BPM pickup electrodes are assembled directly on the vacuum chamber, it is important to calibrate the electrical center offset of the BPM to an adjacent quadrupole magnetic center. A beam based alignment (BBA) method which varies individual quadrupole magnet strength and observes its effects on the orbit is used to measure the BPM offsets in both the horizontal and vertical planes. It is a completely automated technique with various data processing methods. There are several parameters such as the strength change of the correctors and the quadrupoles which should be chosen carefully in real measurement. After several rounds of BBA measurement and closed orbit correction, these offsets are set to an accuracy better than 10 μm. In this paper we present the method of beam based calibration of BPMs, the experimental results of the SSRF storage ring, and the error analysis.     

Study of closed orbit response to magnet vibrations at the SSRF storage ring

This paper presents the analytical and simulation responses of the closed orbit distortion in the SSRF storage ring to random and plane wave like magnet vibrations respectively. It is shown that the use of girder is very beneficial in the view of suppressing this response function. Effect of the independently supported gradient bending magnets to the closed orbit response is given. An analytic formula is written to give a rough estimate of the closed orbit distortion due to ground motion, taking into account the closed orbit response function and girder transfer function. As an example, the result of SSRF case is given.     

同步加速器中束流能量的修正

叙述了同步加速器中束流能量测量和修正的原理,推导出关于闭合轨道畸变和校正二极子强度的束流能量的修正公式,介绍了这些公式在北京正负电子对撞机（BEPC）上的应用,并对其结果进行了讨论．