Sorting of bending magnets for the SSRF booster

The Shanghai Synchrotron Radiation Facility(SSRF)booster ring,a full energy injector for the storage ring,is deigned to accelerate the electron beam energy from 150MeV to 3.5GeV that demands high extraction efficiency at the extraction energy with low beam loss rate when electrons are ramping.Closed orbit distortion(COD)caused by bending magnet field uniformity errors which affects the machine performance harmfully could be effectively reduced by bending magnet location sorting.Considering the affections of random errors in measurement,both ideal sorting and realistic sorting are studied based on measured bending magnet field uniformity errors and one reasonable combination of bending magnets which can reduce the horizontal COD by a factor of 5is given as the final installation sequence of the booster bending magnets in this paper.     

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.     

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.     

Optimal sorting method and application to SSRF booster dipoles

As the dipoles of SSRF booster are powered in series, the magnet field error varies from magnet to magnet and results in bad beam quality. Sorting and installing magnets according to the measured field errors so that the errors on different magnets are partially compensated with each other, has been the easiest way in many cases to reduce the detrimental effects of the errors without introducing complications. Based on the magnet field measurement results, we investigated and implemented the sorting of dipoles using a method mixed by local cancellation and simulated annealing, and it's found to be quite effective.     

Eddy current septum magnets for injection and extraction at SSRF

There are 6 in-vacuum eddy current septum magnets used for booster injection,extraction,and storage ring injection in SSRF.Special attention was paid to coils and their support designs because of the shock force they bear in the magnetic fields and the high heat which is hard to be dissipated in vacuum environment.For the storage ring magnets,good transverse homogeneity in the gap was achieved by careful design,precise machining and accurate assembly;and an extremely low leakage field on the stored beam is another key feature thanks to the high permeability Mu metal.Magnetic field measurement was conducted with both a point coil and a long integral coil,and the results agree well with the OPERA-2d/3d simulations.An inner tube is added to keep the continuity of impedance for the circulating beam with two RF finger flanges at each end.There is no vacuum separation between the inner tube and the magnet chamber.Sputter ion pumps integrated with NEG are used to acquire the UHV for the chamber.     

Special-purpose radiation sources based on the Siberia-2 storage ring

Synchrotron radiation (SR) generated by homogeneous magnetic fields of bending magnets is now employed at the Siberia-2 electron storage ring. It is planned that, in the near future, most of the storage ring’s free straight sections will be equipped with insertion devices (undulators and wigglers). Two projects of specialized radiation sources based on the Siberia-2 stor age ring are discussed. The first source is a vacuum milliundulator intended for generation of extremely bright X-ray beams. An X-ray source with vertically limited diffraction is shown to be feasible when the vertical emittance of an electron beam is equal to the diffraction emittance of photons with an energy of 2 keV. The second source uses edge radiation (ER) generated at the ends of bending magnets of the storage ring. Calculations show that, in the infrared and ultraviolet spectral regions, the ER intensity must exceed the intensity of standard SR formed by the homogeneous field of a bending magnet.     

环形正负电子对撞机注入引出分布参数型冲击磁铁设计

环形正负电子对撞机（CEPC）是一台周长100 km,最高能量为120 GeV的双环对撞机。为了满足不同能量粒子从增强器注入到对撞环,针对W和Z能量模式设计了对撞环离轴注入系统,用于实现束流的累积。为了提高注入效率,兼容不同注入能量,不同束流填充模式,同时尽可能减少注入过程中冲击磁铁对其它束团的扰动,要求对撞环离轴注入冲击磁铁系统是一个上升时间和下降时间小于200 ns,脉冲底宽调节范围为440～2420 ns的梯形波脉冲放电系统。和常见的集中参数型冲击磁铁相比,分布参数型冲击磁铁具有更优越的动态响应特性,适合产生一个前沿更加陡峭、波形更为理想的梯形波脉冲。根据CEPC的束流注入物理需求,完成了一台分布参数型冲击磁铁的物理设计和结构设计,并采用了PSpice和Opera程序进行模拟仿真。设计结果表明：冲击磁铁由26级LC单元结构叠装而成,磁铁总长为1018 mm,磁有效长度为942 mm;在[-20,20] mm磁铁孔径内,磁场强度为0.042 1 T,磁场均匀性优于±0.2%;冲击磁铁系统总上升时间（10%～90%）为193 ns,下降时间（90%～10%）为191 ns。理论分析、...     

Kicker magnet modulator in the 2-GeV Pohang light source

The 2.0-GeV Pohang light source (PLS) is a third-generation synchrotron light source that is the first such facility in Korea and the fifth in the world. The PLS mainly consisted of a full-energy injection linac and a storage ring. Four kicker magnets are installed in the storage ring tunnel to move the stored beam orbit in the storage ring closer to the injected beam from the beam transfer line. The injected beam then falls into the storage ring beam dynamic aperture. A kicker magnet modulator drives all four kicker magnets to maintain field balance and synchronized kick of the beam. Specification of the kicker magnet modulator is ~6.0-μs-full width, 200-ns flattop width with ±0.2% regulation, ~24-kA peak current, and 10-Hz repetition rate. Two thyratron switches (EEV CX-1536AX) are used in the system. As the inverse voltage is dangerous to thyratron operation, a new surge suppression circuit was developed. The kicker modulator has been operated very reliably since its installation in August 1995. In this article, design, simulation, and experimental results of the kicker magnet modulator are discussed. In addition, measurement result of spatial B-field distribution in the kicker magnet and maximum operating range of kicker magnet are discussed     

Excitation curve calibration for the SSRF magnet system

The needed electrical current for the magnet working under different energy loads can be easily calculated once the right relation between the magnet and the electrical current has been found. Therefore the excitation curve calibration for the magnet system is important to the SSRF. The measuring method on the magnet and the result of the excitation curve calibration are presented. The application of the excitation curve calibration for the bending magnet is given, and it is proved that the COD (Closed Orbit Distortion) and the working point of the storage ring are greatly affected by the current of the bending magnet.     

Research and development of an electron beam focusing system for a high-brightness X-ray generator

A new type of rotating anticathode X-ray generator, where an electron beam of up to 60 keV irradiates the inner surface of a U-shaped Cu anticathode, has achieved a beam brilliance of 130 kW mm(-2) (at 2.3 kW). A higher-flux electron beam is expected from simulation by optimizing the geometry of a combined-function-type magnet instead of the fringing field of the bending magnet. In order to minimize the size of the X-ray source the electron beam has been focused over a short distance by a new combined-function bending magnet, whose geometrical shape was determined by simulation using the Opera-3D, General Particle Tracer and CST-STUDIO codes. The result of the simulation clearly shows that the role of combined functions in both the bending and the steering magnets is important for focusing the beam to a small size. FWHM sizes of the beam are predicted by simulation to be 0.45 mm (horizontal) and 0.05 mm (vertical) for a 120 keV/75 mA beam, of which the effective brilliance is about 500 kW mm(-2) on the supposition of a two-dimensional Gaussian distribution. High-power tests have begun using a high-voltage 120 kV/75 mA power supply for the X-ray generator instead of 60 kV/100 mA. The beam focus size on the target will be verified in the experiments.     

Eddy current septum magnets for injection and extraction at SSRF

There are 6 in-vacuum eddy current septum magnets used for booster injection, extraction, and storage ring injection in SSRF. Special attention was paid to coils and their support designs because of the shock force they bear in the magnetic fields and the high heat which is hard to be dissipated in vacuum environment. For the storage ring magnets, good transverse homogeneity in the gap was achieved by careful design, precise machining and accurate assembly; and an extremely low leakage field on the stored beam is another key feature thanks to the high permeability Mu metal. Magnetic field measurement was conducted with both a point coil and a long integral coil, and the results agree well with the OPERA-2d/3d simulations. An inner tube is added to keep the continuity of impedance for the circulating beam with two RF finger flanges at each end. There is no vacuum separation between the inner tube and the magnet chamber. Sputter ion pumps integrated with NEG are used to acquire the UHV for the chamber.     

Uniform transverse beam profile with a new type of nonlinear magnet

In this paper, a new type of magnet is proposed and produced to give a uniform transverse beam profile.Compared to octupole magnets, the new type of magnet can provide a similar octupole magnet field in the middle,but the rise rate declines quickly at the edges, so that a beam of the same uniformity is obtained with less particle loss.Besides that, a mechanical structure is added to adjust the width of the middle region to satisfy different transverse dimensions, which would further reduce particle loss. Some numerical simulations have been done with the octupole and the new type of magnet to show the advantages of the new magnet.     

高能光源增强器束流横向尺寸测量系统设计

高能同步辐射光源的增强器将直线加速器注入的束流加速到储存环所需的能量,为储存环提供高品质的电子束。为了对增强器的束流横向截面尺寸、发射度及能散进行测量,设计了两条可见光-紫外波段的束测光束线。两条光束线分别选取无色散和色散较大的两处弯铁位置作为光源点,使用两套同步光成像系统来监测光源点的束流截面尺寸,并计算束流发射度及能散。介绍了同步光引出真空室及光学成像系统,对影响成像质量的空间分辨率进行了分析,并针对升能过程中不同能量下束流光斑变化的测量进行了设计。     

CSNS/RCS引出系统快脉冲冲击磁铁的磁场仿真和结构设计

中国散裂中子源快循环同步加速器引出系统快脉冲冲击磁铁,由分组安装于三个真空箱内的8台磁铁组成。对冲击磁铁进行磁场仿真和结构设计,并使用仿真软件进行优化。仿真结果表明:磁铁中心场60%宽度内的磁场均匀性达到0.7%,满足物理设计要求。同时,对两台磁铁间距大小与互感的关系进行模拟计算和分析。磁铁结构设计中,针对原样机中出现的铁芯不能可靠固定问题,进行修改和完善,并且设计出了一种简单实用的多螺栓滑动支撑结构,可使多台磁铁平稳推入真空箱内,同时完成多台磁铁的准直和固定。     

磁铁边缘场对注入束流的影响

在兰州重离子加速器冷却储存环工程(HIRFL–CSR)实验环的注入设计过程中,通过对束流在侧面边缘场作用下运动的反向数值跟踪,得到注入束流通过二极磁铁和四极透镜边缘场的传输矩阵,并同理想场对束流的作用进行了比较.通过改变注入束流中心轨道及对磁铁的重新设计,将磁铁边缘场对注入束流的影响减小到可以控制的范围.     

中国散裂中子源磁铁系统和样机研制

中国散裂中子源(China Spallation Neutron Source, CSNS)快循环同步加速器(Rapid Cycling Synchrotron, RCS)磁铁由24块二极磁铁、48块四极磁铁、16块六极磁铁和若干斜四极磁铁以及校正磁铁组成, 其中二极磁铁和四极磁铁是带直流偏置的25Hz正弦交流励磁, 铁芯和线圈导体将产生不可忽视的涡流效应. 为了积累批量生产磁铁的制造经验, 探索磁铁后期处理和磁场测量方法, 已完成了中空水冷铝绞线试样线圈的研制, 启动了二极磁铁和四极磁铁样机的研制. 本文将对相关进展进行介绍.     

光学速调管磁场测量和磁场误差分析

 给出了储存环光学速调管磁场的测量结果,包括轴向分布、横向分布均匀度以及积分场分布;分析了磁场分布的随机误差和系统误差,计算了积分多极场的大小; 讨论了非零积分场引起的闭轨畸变和对储存环工作点的影响。     

Comparison between the Results of Simulating the Synchrotron Radiation from a Bending Magnet and Experimental Data

The results of using two (SPECTRA and SRW) programs for simulating synchrotron radiation (SR) are presented. Calculations are performed for coherent SR from a beam of electrons with moderately relativistic energies in a short bending magnet. Simulation is carried out for real beam parameters. A comparison between simulation and experimental data indicates their good agreement. Both general information for the given codes grouped by a number of criteria and specific data on simulating radiation from bending magnets are presented.     

Effect of undulators on the stored electron beam of Indus-2

Indus-2 is an Indian synchrotron light source, operating at 2.5 Ge V and generating synchrotron radiation from its bending magnets. In order to provide more intense synchrotron radiation to the synchrotron users, there is a plan to install five insertion devices in the Indus-2 storage ring. In the first phase of installation of insertion devices, there is a proposal to install two out- vacuum pure permanent magnet linearly polarized undulators in long straight sections of the Indus-2 storage ring. The presence of the insertion devices in the ring has inevitable effects on beam parameters like betatron tune, betatron amplitude function, closed orbit, emittance, energy spread and dynamic aperture etc. In this paper, the effect of two undulators on the above mentioned parameters of the Indus-2stored electron beam at 2.5 Ge V is presented. Moreover a correction scheme for the restoration of the betatron tune and amplitude function is also presented.     

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.