Vibration Control Research for the 3rd Generation Synchrotron Light Source Storage Ring Mechanical Components

The 3rd generation synchrotron light source requires high level of electron beam orbit stability.Shanghai Synchrotron Radiation Facility (SSRF) is a 3rd generation light source under construction;its orbit stability requirement is up to micro or sub-micro range.The storage ring mechanical components vibration caused by the ground motion would influence the orbit stability.The ground motion of SSRF is severe.It is essential to control the vibration of the mechanical components.Vibration damping is an effective method to control the vibration.The author designed a vibration damping structure for the SSRF mechanical components.The test results show that it can effectively control the mechanical vibration.

Scheme for generating 1 nm X-ray beams carrying orbital angular momentum at the SXFEL

Optical vortices have the main features of helical wavefronts and spiral phase structures,and carry orbital angular momentum.This special structure of visible light has been produced and studied for various applications.These notable characteristics of photons were also tested in the extreme-ultraviolet and X-ray regimes.In this article,we simulate the use of a simple afterburner configuration by directly adding helical undulators after the SASE undulators with the Shanghai Soft X-ray FEL to generate high intensity X-ray vortices with wavelengths^1 nm.Compared to other methods,this approach is easier to implement,cost-effective,and more efficient.

Development of a low-loss magnetic-coupling pickup for 166.6-MHz quarter-wave beta=1 superconducting cavities

166.6-MHz quarter-waveβ=1 superconducting cavities have been adopted for the High Energy Photon Source,a 6-GeV diffraction-limited synchrotron light source currently under construction.A large helium jacket was required to accommodate the enlarged cavity beam pipe for the heavy damping of higher-order modes;the original electric-probe pickup thus becomes inevitably long with unfavorable mechanical properties.Relocated to an existing high-pressure-rinsing port,a magnetic-loop pickup was designed,characterized by low radio-frequency and cryogenic losses and being multipacting-free and insensitive to manufacturing and assembly tolerances.The consequent removal of the original pickup port from the cavity largely simplified the helium jacket fabrication and may also reduce cavity contamination.This paper presents a comprehensive design of a low-loss magnetic-coupling pickup for quarter-waveβ=1 superconducting cavities.The design can also be applied to other non-elliptical structures.

Development of micro-Laue technique at Shanghai Synchrotron Radiation Facility for materials sciences

Synchrotron radiation-based micro-Laue technique has showcased great application potentials in materials science study for its unprecedented crystal orientation and lattice strain/stress resolution.Here we report the updated progress in the development of the micro-Laue technique on the X-ray test beamline at Shanghai Synchrotron Radiation Facility.So far,40μm(h)×50μm(v)X-ray beam spot is routinely obtained,with the convergent angle of 0.2 mrad(h)×0.12 mrad(v).Area scans are conducted on a GH3535 Nibased superalloy base metal and weld joint with the same chemical composition.By analyzing the tremendous amount of Laue diffraction patterns using in-house developed software packages,the crystal orientation,elastic strain,and defect distributions are mapped and investigated.Such a successful proof-of-principle study offers first-hand experience on the further optimization of the design and construction of the scanning micro-Laue facility on the superbend beamline with improved spatial resolution and multiple functions for simultaneous chemical fluorescence mapping and in-situ microstructural evolution studies.The micro-Laue diffraction beamline at Shanghai Synchrotron Radiation Facility will provide a versatile and powerful tool for the orientation and strain/stress mapping combined with phase identification with micron-sized spatial resolution.

Stable femtosecond X-rays with tunable polarization from a laser-driven accelerator

Technology based on high-peak-power lasers has the potential to provide compact and intense radiation sources for a wide range of innovative applications.In particular,electrons that are accelerated in the wakefield of an intense laser pulse oscillate around the propagation axis and emit X-rays.This betatron source,which essentially reproduces the principle of a synchrotron at the millimeter scale,provides bright radiation with femtosecond duration and high spatial coherence.However,despite its unique features,the usability of the betatron source has been constrained by its poor control and stability.In this article,we demonstrate the reliable production of X-ray beams with tunable polarization.Using ionization-induced injection in a gas mixture,the orbits of the relativistic electrons emitting the radiation are reproducible and controlled.We observe that both the signal and beam profile fluctuations are significantly reduced and that the beam pointing varies by less than a tenth of the beam divergence.The polarization ratio reaches 80%,and the polarization axis can easily be rotated.We anticipate a broad impact of the source,as its unprecedented performance opens the way for new applications.

Design and test of support for HEP Smagnets

Purpose High Energy Photon Source(HEPS)has the characteristics of high energy and low emittance,which requires that the 1st natural frequency of the magnet support assembly should be better than 54 Hz and the moving resolution of girder should be less than 5μm.The prototypes have been designed and fabricated to meet the requirements.Methods In the design process of the support system model,double-wedge adjusting mechanism and concrete plinth construction are adopted to meet the requirements of adjusting resolution and stability.The FEA and the dynamic stiffness testing technique are used to verify the rationality of the design model.The stability and motion performance tests are performed to verify that the prototype meets the design requirements.Results Experimental results showthat,in all cases,the lowest first-order natural frequency of the support system is 55Hz,the amplification between magnet and ground is less than 1.05 in the directions perpendicular to the beam,the moving resolution can reach 1μm,and the girder can be locked in place with an error of less than 5μm.Conclusion The prototype of HEPS support system meets the requirements of stability and motion performance.The girder body and wedge mechanism made with iron or steel have little influence on the stability of the support system.The accuracy of dynamic stiffness test and finite element simulation results is verified.Further test will be performed in the HEPS site to verify the performance.

Laser technology in Poland： 2013-2016

This paper presents the state of art of laser technologies in Poland. A list of primary laser technology development centers is included. The involvement of Polish scientists in the development of lasers and fourth generation synchrotron light sources as well as their applications is discussed. The development of laser applications in medical therapy and diagnostics, material micro- and macro-processing as well as environmental monitoring and protection, safety, and security is presented.