合肥先进光源储存环初步物理设计

我国最近立项建设的合肥先进光源将是一台软X射线与真空紫外衍射极限储存环光源,其电子束能量为2.2 GeV,周长为480 m,束流自然发射度为86 pm·rad,共有20个长直线节和20个短直线节。介绍了目前合肥先进光源储存环物理设计的进展情况,包括磁聚焦结构设计与优化,束流注入和集体效应的模拟与计算。     

Lattice optimization for the HLS-Ⅱ storage ring

The upgrade project of the Hefei Light Source (HLS), named HLS-Ⅱ , is under way, which includes the reconstruction of its storage ring. The HLS-Ⅱ storage ring has lower emittance and more straight sections available for insertion devices as compared with the present HLS storage ring. The scan method is applied to the linear lattice optimization for the HLS-Ⅱ storage ring to get thorough information about the lattice. To reduce the amount of computation, several scans with different grid spacing values are conducted. In addition, the calculation of the chromatic sextupole strength for the achromatic mode is included in the scan, which is useful for nonlinear lattice optimization. To better analyze the obtained solutions in the scan, the lattice properties and the variables of quadrupole strengths are statistically analyzed. The process of selecting solutions is described in detail, including the choice of the working point, the settings for the emittance and optical functions, and the restriction of maximum magnet strength. Two obtained lattices, one for the achromatic mode and the other for the non-achromatic mode, are presented, including their optical functions and optimized dynamic apertures.     

第四代同步辐射光源物理设计与优化

近十年来,世界上开始大力发展第四代同步辐射光源——衍射极限储存环光源。目前我国正在建设或立项建设两台第四代同步辐射光源:高能同步辐射光源和合肥先进光源。从储存环磁聚焦结构设计与优化、束流注入与集体效应等方面,对第四代同步辐射光源的物理设计与优化进行了介绍;对国际范围内第四代储存环光源装置的研制情况进行了介绍。     

Lattice study for the HLS-Ⅱ storage ring

The Hefei Light Source (HLS) is undergoing a major upgrade project, named HLS-Ⅱ , in order to obtain lower emittance and more insertion device straight sections. Undulators are the main insertion devices in the HLS-Ⅱ storage ring. In this paper, based on the database of lattice parameters built for the HLS-Ⅱ storage ring obtained by the global scan method, we use the quantity related to the undulator radiation brightness to more directly search for high brightness lattices. Lattice solutions for achromatic and non-achromatic modes are easily found with lower emittance, smaller beta functions at the center of the insertion device straight sections and lower dispersion in non-zero dispersion straight sections compared with the previous lattice solutions. In this paper, the superperiod lattice with alternating high and low horizontal beta functions in long straight sections for the achromatic mode is studied using the multiobjective particle swarm optimization algorithm.     

束内散射效应下HALF储存环物理参数的优化设计

合肥先进光源（HALF）是我国规划建设的软X射线与VUV衍射极限储存环光源（DLSR）。如何有效地实现衍射极限束流发射度,是DLSR物理设计中的核心问题之一。基于束流发射度演化方程,针对HALF预研项目的储存环物理设计方案,计算了束内散射（IBS）效应带来的发射度增长,研究了DLSR中关键参数选择对IBS造成的发射度增长的影响。研究表明,在中低能DLSR物理设计中需要综合考虑储存环的周长、同步辐射阻尼时间等关键参数,以更好地抑制束流发射度的增长。在此研究基础上,通过综合考虑用户需求与储存环物理要求,提出了HALF当前工程项目的储存环物理设计方案。进一步综合应用束团拉伸、全耦合等措施后,更高效地抑制了HALF储存环内IBS造成的束流发射度增长。     

衍射极限储存环束流注入物理方案的设计及模拟

衍射极限储存环（DLSR）作为第四代同步辐射光源，正得到世界各国的大力发展和建设。如何在尽量减小对存储束流扰动情况下，高效率地将束流注入到储存环中，是衍射极限储存环设计与运行中的重要课题之一。传统的局部凸轨注入法有着很长的历史，应用广泛且技术成熟，但是传统凸轨注入法会对存储束流造成扰动，且衍射极限储存环的动力学孔径较小，这给传统凸轨注入法的应用带来了困难。为了解决这些问题，改进了一些传统的离轴注入法，提出并发展了一些在轴的注入方法。合肥先进光源（HALF）是规划建设中的衍射极限储存环光源，基于HALF储存环的物理设计方案，设计并应用了几种离轴或在轴的注入方案，通过粒子跟踪和模拟的方法验证了它们的可行性并研究了注入效率等物理问题，并对模拟结果进行了讨论和总结。