• G. Feng, W. Fan, W.W. Gao, W. Li, L. Wang, S.C. Zhang
  USTC/NSRL, Hefei, Anhui

In order to obtain more straight sections for insertion devices and higher brilliance synchrotron radiation, an upgrade project of Hefei Light source (HLS) is undergoing. A new injection system has been designed to improve injection efficiency and keep the machine running stably. Four kickers will be used to generate a local injection bump. Effects of injection system to injecting beam and stored beam have been simulated considering errors. Finally, ELEGANT code was used to simulate the injection process with new designed bump system. The simulation results show that the injection efficiency would be higher than 99% and perturbation on stored beam would be small enough, which are benefit to full energy injection and top-up operation of HLS in the future.

• W. Fan, G. Feng, D.H. He, W. Li, L. Wang, S.C. Zhang
  USTC/NSRL, Hefei, Anhui

Hefei Advanced Light Source(HALS) will be a high brightness light source with about 0.2nmrad emittance at 1.5GeV and about 400m circumference. To enhance brilliance, very low beam emittance is required. High brightness demand and relative low energy will make emittance a critical issue in ring design. Intra-beam scattering(IBS) is usually thought a fundamental limitation to achieve low emittance. Here we preliminarily estimate the emittance growth due to IBS for the temporary lattice design of HALS based on Piwinski and Bjorken-Mtingwa theories, and discuss the effect of implementation of damping wiggler and harmonic cavity to lower the emittance.

• G. Feng, W. Fan, W.W. Gao, W. Li, L. Wang, H. Xu, S.C. Zhang
  USTC/NSRL, Hefei, Anhui

HLS (Hefei Light Source) is a dedicated synchrotron radiation research facility, whose emittance is relatively large. In order to improve performance of the machine, especially getting higher brilliance synchrotron radiation and increasing the number of straight sections for insertion devices, an upgrade project is on going. A new low emittance lattice, which keeps the circumference of the ring no changing, has been studied and presented in this paper. For the upgrade project, a new ring will be installed on current ground settlement of HLS and all of the magnets will be reconstructed. After optimization, two operation modes have been chosen for different users. Nonlinear dynamics shows that dynamic aperture for on-momentum and off-momentum particle is large enough. Beam lifetime has also been studied. Calculation results proves that expected beam lifetime about 8.5 hours can be obtained with a fourth harmonic cavity operation.

• L. Wang, W. Fan, G. Feng, W.W. Gao, W. Li, H. Xu, S.C. Zhang
  USTC/NSRL, Hefei, Anhui

The Hefei Light Source is composed of an 800 MeV storage ring, a 200 MeV electron linac and transfer line, which was designed and constructed twenty years ago. Several factors limit the performance of HLS, for example, less number of insertion devices and large beam emittance. To meet the requirements of synchrotron radiation users, an upgrade project of HLS will be carried out in the next two years. Several sub-systems will be renewed, such as magnet system, power supply, beam diagnostics, vacuum system, etc. The upgrade scheme is described in this paper, including magnet lattice design, nonlinear performance, collective effects,beam injection, orbit detection and correction, injector, etc.

• C.-F. Wu, H. Fan, W. Fan, G. Feng, W.W. Gao, K. Jin, W. Li, G. Liu, L. Wang, S.C. Zhang, Y. Zhao
  USTC/NSRL, Hefei, Anhui
• R.A. Bosch
  UW-Madison/SRC, Madison, Wisconsin

A radio frequency system with a higher-harmonic cavity will be used to increase the beam lifetime and suppress coupled-bunch instabilities of the upgrade Hefei Light Source. In the paper, the simulated results confirm that tuning in the harmonic cavity may suppresses the parasitic coupled-bunch instabilities. The higher-harmonic cavity has been designed and the calculated optimum lifetime increase ratio is 2.58.

• W.W. Gao, W. Li, L. Wang
  USTC/NSRL, Hefei, Anhui

Low emittance is a desirable performance for high brightness synchrotron light source and damping ring. The work presented in this paper demonstrates that the lattice of a given electron storage ring, which has fixed circumference and magnet layout, can be optimized to obtain low emittance by using MOGA (Multi-objective Genetic Algorithm). Both dispersion-free and non-dispersion-free lattices of HLS (Hefei Light Source) upgrade project are computed as an illustration. Simulation result shows that this method is fast and straightforward.

• S.C. Zhang, W. Fan, G. Feng, W.W. Gao, H. Geng, Z.G. He, W. Li, L. Wang, H. Xu
  USTC/NSRL, Hefei, Anhui

In order to meet the increasing requirements of synchrotron radiation users, an upgrading plan of hefei light source is undergoing by National Synchrotron Radiation Laboratory (NSRL). The emittance of storage ring is reduced from 166nm.rad to 36nm.rad. In this paper, we study the beam close orbit distortions' (COD) sensitivity to the field and alignment errors in magnets. Estimation of the COD from various error sources is investigated. The distribution of beam position monitors and the location of correctors are reported in the paper. Simulation proves that COD can be corrected down to 50 microns level. In the same time the corrector strengths are weaker enough in the correction scheme.

• S.C. Zhang, W. Fan, G. Feng, W.W. Gao, W. Li, L. Wang, H. Xu
  USTC/NSRL, Hefei, Anhui

To enhance the performance of Hefei Light Source, an upgrade project is undergoing. The magnet lattice of storage ring will be reconstructed with 4 DBA cells, whose advantages are lower beam emittance and more straight section available for insertion devices. In order to assure smooth beam accumulation process under new low emittance lattice, the injector, which is composed of electron linac and beam transfer line, would be updated. The detail of upgrading Hefei Light Source transport line will be described in this paper. It include the upgrading of lattice, the orbit control of beam transfer line and others. It is hopeful to realize a high transfer efficiency and high injection efficiency for new lower beam emittance storage ring.