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

HALS(Hefei Advanced Light Source) is the electron storage ring of ultra-low emittance in process of design. Under this design, the quadrupole magnet with sextupole component must be mounted on which the βη is much bigger, to use enough the effect of compersation chromaticity of sextupole magnet field and to use sparingly the space in the same time . So the combined quadrupole and sextupole magnet must be designed, and have more strong sextupole component and restrain the production of high harmonic field. In this paper, the chocie of design scheme is discussed, and the calculation of combined quadrupole and sextupole mangnet design is given.

• S.C. Zhang, G. Feng, W. Li, L. Liu, L. Wang, C.-F. Wu, H. Xu
  USTC/NSRL, Hefei, Anhui

Funding: supported by National Natural Science Foundation of China (10705027)

Hefei Advanced Light Source(HALS) is a super low emittance storage ring and has a very poor beam life time. In order to run the ring stablely, Top-up injection will be necessary. Injection system will greatly affect the quality of beam. This article first give a physics design of injecting system. Then the injecting system is tracked under different errors. The responses of storage beam and injecting beam is given in the article.

• J.Q. Lan, B. Sun, H. Xu, J. Zhang
  USTC/NSRL, Hefei, Anhui

Radial alternating magnetic field is generated to act on polarized beam to give rise to resonant depolarization and calibrate the energy of electron by feeding power to a pair of vertical installed striplines in HLS. In the paper, the relationship between depolarization time and power fed into the striplines is investigated, and spin frequency spread is considered too. As a result, a depolarization time of 60s is acquired with an amplifier power of 15W fed into the striplines.

• J.G. Wang, B. Sun, B.Y. Wang, H. Xu
  USTC/NSRL, Hefei, Anhui

In HLS streak camera system has been built. The system is used to measure some parameters of bunch like bunch length, longitudinal bunch profile and synchrotron frequency and so on, as it may report a direct derivation of fundamental machine characteristics. The system mainly consists of the synchrotron light extracting optics setup, the OPTOSCOPE streak camera and PC with a frame grabber interface card. The light extracting optics setup is used to extract synchrotron light at the bending magnet and the setup consists of the light extracting path and the optics imaging system. The streak camera realizes the functions of acquiring light and imaging. PC with a frame grabber interface card and ARP-Optoscope software package is used to monitor the light in real-time, acquire the image of light and analyze the data. The streak camera system operates with either synchroscan sweep mode or dual time base sweep mode. At present, some results are given, which include the bunch lengthening, the longitudinal bunch profile and the synchrotron frequency. These results are compared with the results acquired by using oscilloscope.

• G. Feng, W. Li, L. Liu, L. Wang, C.-F. Wu, H. Xu, S.C. Zhang
  USTC/NSRL, Hefei, Anhui

In order to meet the increasing requirements of synchrotron radiation users, a new plan of VUV and soft X-ray light source, named Hefei Advanced Light Source (HALS), is brought forward by National Synchrotron Radiation Laboratory (NSRL). This 1.5GeV storage ring with ultra low emittance 0.2nmrad consists of 18 combined FBA cells and the circumference is 388m. Strong enough quadrupoles and sextupoles must be needed for getting such low emittance lattice, which will lead beam close orbit distortions’ (COD) sensitivity to the field and alignment errors in magnets. Estimation of the COD from various error sources is investigated. Using orbit response matrix and singular value decomposition method, 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 60 microns level. In the same time the corrector strengths are weaker enough in the correction scheme.