Highly coupled off-resonance lattice design in diffraction-limited light sources

The round-beam operation presents many benefits for scientific experiments regarding synchrotron radiation and the weak-ening influences of intra-beam scattering in diffraction-limited synchrotron light sources.A round-beam generation method based on the global setting of skew quadrupoles and the application of a non-dominated sorting genetic algorithm was pro-posed in this study.Two schemes,including large-emittance coupling introduced via betatron coupling and vertical disper-sion,were explored in a candidate lattice for an upgrade-proposal of the Shanghai synchrotron radiation facility.Emittance variations with lattice imperfections and their influence on the beam dynamics of beam optic distortions were investigated.The results demonstrated that a precise coupling control ranging from 10 to 100%was achieved under low optical distortion,whereas full-coupling generation and its robustness were achieved by our proposed method by adjusting the skew quadrupole components located in the dispersion-free sections.The Touschek lifetime increased by a factor of 2–2.5.

Intra-beam scattering and beam lifetime in a candidate lattice of the soft X-ray diffraction-limited storage ring for the upgraded SSRF

New-generation synchrotron light sources are being designed and operated worldwide to provide brighter radiation by reducing the beam emittance to X-ray diffraction limits.Intra-beam scattering(IBS)and Touschek scattering in such facilities are significant and require attention because of their ultra-low emittance.Therefore,cure strategies need to be carefully studied to obtain highquality photon beams.For the Shanghai Synchrotron Radiation Facility Upgrade(SSRF-U),a candidate lattice of the storage ring,reaching the soft X-ray diffraction limit,was designed and presented for the first time in this study.The emittance growth and beam lifetime in the SSRF-U storage ring were studied using particle simulations for a series of different machine configurations.The gains with RF frequencies of 100 MHz and 500 MHz were compared.Along with a better filling pattern,a more suitable RF frequency was adopted in the SSRF-U.The variations in the equilibrium beam emittance with beam coupling and bunch-lengthening were identified using simulations.Optimal beam coupling and required bunch-lengthening for the SSRF-U storage ring were thus determined.The fitness of the beam energy in the SSRF-U was subsequently assessed using the obtained parameters.Additionally,the Touschek scattering and beam lifetime were calculated,and an acceptable total beam lifetime was obtained.

A Criteria Model for Budgeting and Assessing Industrial Sites Location in Developing Economy

Industrial sites are selected in many of the developing countries without taking into consideration some pertinent criteria that are directly affecting the sustainability of such industries in the locations after commissioning. Industries are located in some areas based on political influence rather than facility availability that support industry＇s productivity. In this study a criteria model was developed for assessing the present industrial site locations based on predetermined influencing factors called criteria. In the model provision was made for the sorting out of deficient influencing factors for the purpose of upgrading them to the minimum level required called benchmark through periodical allocation of appropriate funds. In validating the model, identified industrial sites located in selected States of Nigeria were surveyed. Data were collected on factors such as power supply, marketability and raw malerial availability which were considered influential to the sustainability of industry＇s site in the respective areas. Data were analysed for the criteria identified along the line of industrial categories which included large-, medium-, and small-scales. Benchmarks, as well as levels of criteria in the respective regions were determined using statistical weighted averages and the results were used as input to the model. The output results of the model showed that none of the industrial sites located in the selected six States of the South-Western Nigeria were productivity supportive. However, a good performance was achieved in a site with a budget of S13 million （US Dollars） for the upgrading of the deficient facilities in the next three years.

PEPX-type lattice design and optimization for the High Energy Photon Source

A new generation of storage ring-based light sources, called diffraction-limited storage rings（DLSR）, with emittance approaching the diffraction limit for multi-ke V photons by using multi-bend achromat lattice, has attracted worldwide and extensive studies of several laboratories, and been seriously considered as a means of upgrading existing facilities in the imminent future. Among various DLSR proposals, the PEPX design demonstrated that it is feasible to achieve sufficient ring acceptance for off-axis injection in a DLSR, by designing the lattice based on the ‘thirdorder achromat’ concept and with a special high-beta injection section. For the High Energy Photon Source（HEPS）planned to be built in Beijing, a PEPX-type lattice has been designed and continuously improved. In this paper, we report the evolution of the PEPX-type design for HEPS, and discuss the main issues relevant to the linear optics design and nonlinear optimization.