Beam based alignment (BBA) plays an important role in the commissioning of the fourth generation light source but it takes a lot of time with several hundreds of BPMs. To speed up BBA, a method using AC excitation, called fast BBA, has been proposed and is tested in several 3rd generation light sources. We have recently also proposed and tested a new BBA based on the neural network machine learning. In this paper, we will compare these new BBAs with conventional BBA in term of error, speed and some other aspects such as the betatron coupling.

Jinhua light source (JHLS) is a synchrotron radiation facility with the aim of the increasing requirement of user demands for industrial applications. The lattice contains 16 super-periods in order to accommodate different end users for experiments. The circumference is less than 240 m, and the natural emittance is less than 10 nm∙rad at 2.6 GeV. In this paper, we present a modified Triple Bend Achromat (TBA) lattice as the preliminary design for the JHLS storage ring. The ‘sandwich’ longitudinal gradient bends and horizontal defocusing bends are introduced into lattice in order to decrease the natural emittance. The detail design is reported in this paper.

Hefei Light Source (HLS) is a small and compact synchrotron light source with an electron beam energy of 800 MeV and a circumference of 66.13 m. The storage ring lattice adopts the Double-Bend Achromat (DBA) structure with 4 super periods. Considering the future upgrade of the injection system by using a nonlinear kicker (NLK), we optimize the dynamic performance of the storage ring. The optimization mainly aims at increase the dynamic aperture and beam lifetime, which helps improve the injection efficiency for the new injection scheme. While keeping the current layout of the lattice, the linear optics is also modified in order to improve its nonlinear performance. In this paper, we represent our work on the optimization of the HLS-II storage ring.

Hefei advanced light facility (HALF) is a fourth-generation light source under construction. Its storage ring is a diffraction-limited one with an energy of 2.2 GeV and an extremely low emittance of less than 100 pm·rad. The real storage ring is different from the ideal lattice due to various kinds of errors. Those errors come from many sources, like misalignment of components, imperfect magnetic fields, RF cavity, etc. Due to the strong nonlinear nature and small dynamic aperture of the HALF storage ring, those errors significantly increase the difficulty of its commissioning. To figure out the practical performance of the lattice with those errors, a start-to-end commission simulation is performed in this study, which also helps to generate effective commissioning process for the HALF storage ring.