Feedforward compensation of the insertion devices effects in the SSRF storage ring

The lattice of the Shanghai Synchrotron Radiation Facility(SSRF) storage ring was upgraded in the Phase-II beamline project, and thus far, 18 insertion devices(IDs) have been installed. The IDs cause closed-orbit distortions, tune drift, and coupling distortions in the SSRF storage ring, all of which are significant issues that require solutions. In this study, an ID orbit feedforward compensation system based on a response matrix using corrector coils was developed, and it was applied to all commissioned IDs in the SSRF storage ring. After correction, the maximum ID-induced horizontal and vertical orbit distortions were less than 5.0 and 3.5 μm, respectively. Some interesting phenomena observed during the measurement process were explained. Additionally, optical and coupling feedforward systems were developed using quadrupole and skew quadrupole magnets installed on the front and back of elliptically polarizing undulators(EPUs). Moreover, over nearly four months of operation, the developed strategy delivered a satisfactory performance in the SSRF storage ring.

ID effects on beam dynamics in the SSRF-U storage ring

This paper introduces the proposed insertion device(ID)scheme for the Shanghai Synchrotron Radiation Facility Upgrade.Based on this scheme,the influences of the ID radiation on the intra-beam scattering emittance and energy spread were evaluated.Optical distortion caused by the IDs was comprehensively examined and compensated using both local and global corrections.Subsequently,a frequency map analysis method was used to identify potentially dangerous resonance lines.In addition,the dynamic aperture,energy acceptance,and Touschek lifetime were calculated after considering high-order magnetic field errors to ensure that the ID effect did not affect the operation of the storage ring.

Design, assembly, and pre-commissioning of cryostat for 3W1 superconducting wiggler magnet

One of the most important devices for the High Energy Photon Source Test Facility project,the 2.6 T 32-pole 3W1 superconducting wiggler,was designed by the Institute of High Energy Physics(IHEP);its magnetic gap is 68 mm,and its storage energy is 286 kJ.It will be installed at the storage ring of the Beijing Electron Positron Collider Upgrade Project at the IHEP to replace the old permanent wiggler.The primary purpose of the cryostat is to create a safe and reliable system and realize long-term operation with zero liquid helium consumption.To maintain liquid helium temperature,four identical two-stage cryocoolers are placed symmetrically at the wiggler ends.The cryostat has only one 60 K thermal shield,which is used to reduce the heat load to the liquid helium vessel.The cryostat has several novel features,including a suspension system with little heat leakage that is self-centered during cooling of the cryostat,a special copper liner and high-efficiency condensers,three pairs of binary current leads,and three-level safety design.The cryogenic system has been cooled three times,and the residual cooling capacity is approximately 0.41 W at 4.2 K without current.

Mechanical design of a cryogenic Delta-Knot undulator for high energy photon source

Introduction A novel type of pure permanent cryogenic Delta–Knot Undulator was developed at IHEP to supply a high flux of full adjustable polarization synchrotron radiation with low on-axis power density.This prototype was an active attempt and early exploration for future APPLE–Knot undulator,which will be used at high energy photon source(HEPS).Materials and methods There are several challenges to develop a cryogenic delta undulator,such as the complicated structure,the influence of large magnetic force,and the magnetic measurement difficulty due to the very small gap.In this paper,the mechanical design for overcoming these difficulties will be presented in detail.Conclusion A special hall measuring system is developed,and the preliminary results agree with the theoretical results.This undulator prototype will provide valuable experience for angle magnetization technology,intricate magnetic attraction structure design,and magnetic field measurement under closed small space.

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.