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.     

New chromaticity compensation approach and dynamic aperture increase in the SSRF storage ring

Strong chromatic sextupoles used to compensate natural chromaticities in the third generation light source storage ring usually reduce dynamic aperture drastically. Many optimization methods can be used to find solutions that provide large dynamic apertures. This paper discusses a new optimization approach of sextupole strengths with step-by-step procedure, which is applied in the SSRF storage ring, and a better solution is obtained. Investigating driving terms generated by the sextupoles in every step can analyze their convergences and guide the weight setting among different terms in object function of the single resonance approach based on the perturbation theory.     

上海光源储存环束流托歇克寿命研究

上海同步辐射装置(SSRF)是目前在建的第3代专用同步辐射光源. 其储存环电子能量3.5GeV, 设计束团发射度3.9nm•rad. 托歇克寿命将是影响束流寿命的最主要因素, 它主要受限于储存环的能量接受度. 储存环的能量接受度不但取决于 高频电压, 同时也受动力学孔径和物理孔径的影响. 因此能量接受度的计算将是复杂的. 通过计算机模拟跟踪的方法计算储存环各点的能量接受度, 其程序是建立在Accelerator Toolbox(AT)基础上的自编程序. 通过这些能量接受度数据给出更加准确的托歇克寿命, 并且分析了感兴趣的不同运行条件下的托歇克寿命的变化情况.     

上海光源储存环磁聚焦结构设计

上海光源是一台正在建设中的低发射度第三代同步辐射光源. 经过优化后, 储存环有两种直线节长度, 周长432m,在能量3.5GeV下束流发射度为3.9nm.rad, 直线节处的β函数和色散函数有足够的调节范围. 跟踪研究表明, 即使带上磁铁高阶场误差, 储存环仍有足够大的动力学孔径和能量接受度.     

Improved nonlinear optimization in the storage ring of the modern synchrotron radiation light source

In the storage ring of the third generation light sources, nonlinear optimization is an indispensable course in order to obtain ample dynamic acceptances and to reach high injection efficiency and long beam lifetime, especially in a low emittance lattice. An improved optimization algorithm based on the single resonance approach, which takes relative weight and initial Harmonic Sextupole Integral Strength （HSIS） as search variables, is discussed in this paper. Applications of the improved method in several test lattices are presented. Detailed analysis of the storage ring of the Shanghai Synchrotron Radiation Facility （SSRF） is particularly emphasized. Furthermore, cancellation of the driving terms is investigated to reveal the physical mechanism of the harmonic sextupole compensation. Sensitivity to the weight and the initial HSIS as well as dependence of the optimum solution on the convergent factor is analyzed.     

Studies of closed orbit correction and slow orbit feedback for the SSRF storage ring

Details of the active ways to suppress Closed Orbit Distortion （COD）, including bending magnet sorting and survey and alignment of the magnets, are discussed based on the studies of affections to the COD by the bending magnet field error and the misalignment of quadrupoles. The closed orbit correction and the Slow Orbit Feed Back （SOFB） system for the SSRF storage ring are presented in this paper. With these available methods, better results were obtained during the commissioning period with 3 GeV beam energy.     

上海光源储存环横向反馈系统模拟计算

在同步辐射光源中, 阻抗壁不稳定性是一个很严重的问题. 要保证储存环在高流强下正常运行, 就需要安装一套横向反馈系统. 为了了解在横向反馈作用下束流的动力学性质,建立了一套横向反馈模拟计算程序. 并用该程序模拟计算了上海光源储存环横向反馈系统在闭轨误差(COD)、束流位置探测器读数误差以及梳状滤波等条件改变下的反馈效果.     

Analysis of sextupole effects on β function beating in the SSRF storage ring

In a storage ring, asymmetry of the β function with momentum deviation is the main reason for asymmetry of the dynamic aperture. This paper applies simulation method based on AT code in Matlab to investigate sensitivity of the β function beating and the tune shift to quadrupole field error with the presence of bending field error in the Shanghai Synchrotron Radiation Facility (SSRF) storage ring. Sextupole effect on the variation trend is analyzed. Dynamics of the lattice for working points close to and away from the second order structural resonance stop-band are compared. These results show that the β function beating with momentum deviation doesn't lie in the influence of the second order structural resonance stop-bands completely, but it is relevant to lattice structure.     

Physics design of SSRF synchrotron radiation security

High brightness of SSRF brings about synchrotron radiation security problems, which will be solved in physics design. The main radiations are generated from bending magnets and insertion devices. Since the fact that radiation power and radiating area are different in these two kinds of synchrotron radiation, the arrangements of photon absorbers, diaphragms and other vacuum components need to be treated distinctively. In addition, SSRF interlock protection threshold is defined and the beam orbit in the straight line is limited. Hence, beam orbit in the bending magnets and IDs are also restricted by the threshold. The orbit restriction is calculated and helps us to arrange the vacuum components. In this paper, beam orbit distortion restricted by interlock protection threshold, radiation power, radiation angle and illuminating area are calculated. From the calculation results, the physics designs in manufacture and installation vacuum components are put forward. By commissioning, it is shown that physics requirements are met rigidly in the engineering process.     

基于响应矩阵和SVD算法的输运线束流轨道校正

在输运线中, 磁铁的加工及安装误差所产生的二极磁场分量会导致束流运动轨道偏离理想轨道. 采用基于Matlab的AT程序, 利用响应矩阵和SVD算法, 对SSRF高能输运线磁铁布局方案进行了轨道畸变校正, 对不同的校正子和BPM放置方案作了比较研究, 并对SVD算法中截断阈值的选取对输运线束流轨道畸变校正的效果作了比较研究.