Author: Li, W.
Paper Title Page
MOPME038 A New Theoretical Design of BLM System for HLS II 553
  • Y.K. Chen, L.J. He, J. Li, W. Li, Y. Li
    USTC/NSRL, Hefei, Anhui, People's Republic of China
  Beam loss monitoring (BLM) system has been commonly used to detect the vacuum leakage. The existing BLM system for Hefei Light Source (HLS) was built in 2000. It played an important role in analyzing beam loss distribution and regulating the machine operation parameters. Recently, HLS is being upgraded to HLS II. The emittance will be decreased to increase the brilliance of synchrotron radiation. The Touschek lifetime will be much shorter than before, and dominate the total beam lifetime. It is necessary to redesign the BLM system for HLS II. The most important part of this work is to find a better method of monitoring Touschek lifetime by BLM system while keeping its general functions. According to the results of our research, a preliminary theoretical design for the new BLM system is proposed in this paper. This new system will play an important role in the storage ring commissioning, troubleshooting, and beam lifetime studying.  
TUPWA024 The Beam Gass Coulomb Scattering in Electron Storage Ring 1778
  • X.L. Yu, Z. Bai, W.W. Gao, W. Li, L. Wang
    USTC/NSRL, Hefei, Anhui, People's Republic of China
  Among the various factors which determine the beam life time of the HLSII electron storage ring, the beam loss due to the scattering on residual gas is simulated using MC method. The paper will give the process of elastic and inelastic scattering, and the probability of each scattering is calculated, then using MC sampling to decide which particles will participate in the collision. Tracking the beam with scattering of beam-gas included, the spatial distribution of beam will be obtained. Finally we will give the influence analysis of beam-gas scattering.  
TUPWA030 Impedances Calculations of Bellows in HLS II Storage Ring 1784
  • Q. Zhang, W. Li, L. Wang
    USTC/NSRL, Hefei, Anhui, People's Republic of China
  The upgrade project of Hefei Lighe Source storage ring is carrying on.In this project,a new Bellows, in which shielding is provided by sprung fingers which can slide along the beam screen,is installed at the accelerator interaction area In order to reduce this impedance to an acceptable value. The contributions of Bellows to short range wakefields and broadband impedance were calculated numerically by Mafia code .  
TUPWO063 Reducing HLS-II Emittance by Radiation Damping Partition Factor Exchange 2009
  • J.Y. Li
    FEL/Duke University, Durham, North Carolina, USA
  • W. Li, G. Liu, W. Xu
    USTC/NSRL, Hefei, Anhui, People's Republic of China
  • Y. Li
    BNL, Upton, Long Island, New York, USA
  Funding: The Introduction of Outstanding Technological Talents Program of Chinese Academy of Sciences, 2010.
In this paper, we present a preliminary study on using a Robinson wiggler, a wiggler with transverse gradient, to reduce the horizontal beam emittance of the Hefei Light Source II (HLS-II) storage ring. A proof-of-principle study demonstrates that it is possible to further reduce the horizontal beam emittance by 50\% using a 2-meter long Robinson wiggler installed on a dispersive straight section. This encouraging result suggests a feasible option to significantly improve the HLS-II performance at a relative low cost and without significant modification to its global configuration in the near future.
WEPEA025 Chromatic Sextupole Pair Optimization Methods for Enlarging Dynamic Aperture 2555
  • Z. Bai, Q.K. Jia, W. Li, L. Wang, Q. Zhang
    USTC/NSRL, Hefei, Anhui, People's Republic of China
  Based on the step-by-step chromaticity compensation method [1] and artificial intelligence algorithms, we propose new numerical methods, called chromatic sextupole pair optimization methods, for enlarging the dynamic aperture of electron storage rings. In the new methods, the decision variables related to chromatic sextupole pairs are optimized using artificial intelligence algorithms to enlarge the dynamic aperture. We demonstrate that the new methods are equivalent to the recently used numerical method, in which the decision variables, sextupole strengths, are optimized using artificial intelligence algorithms.
[1] E. Levichev, P. Piminov, Proceedings of EPAC 2006, p. 2116.
WEPEA027 Nonlinear Model Calibration in Electron Storage Rings via Frequency Analysis 2558
  • G. Liu, W. Li, L. Wang, K. Xuan
    USTC/NSRL, Hefei, Anhui, People's Republic of China
  Frequency analysis of turn-by-turn BPM data is a very useful numerical method for analysing the detrimental effect of the nonlinear resonances in storage rings, and which has been widely used for nonlinear resonances measurement and correction. We applied this method in this paper for calibrating the nonlinear model by numerical fitting of the sextupole components with the effect of radiation damping and decoherence of the betatron oscillation in HLSII storage ring.  
THPEA015 Induced Radioactivity Research for Scraper 3173
  • L.J. He, Y.K. Chen, W. Li
    USTC/NSRL, Hefei, Anhui, People's Republic of China
  The 200MeV electron linac of NSRL is one of the earliest high-energy electron linear accelerators in China. The electrons are accelerated to 200MeV by five accelerating tubes and collimated by the scraper followed each accelerating tube. The scraper aperture is smaller than the accelerating tube,so some electrons will hit on the structure materials when they pass through them. These lost electrons will cause induced radioactivity due to bremsstrahlung, cascade shower and photo-nuclear reaction. This paper gives the simulation to different energy electrons lost at the corresponding scraper by EGSnrc. The results showed that electrons were lost mainly at the scraper during the accelerating period,and the actual measurement confirmed this. Meanwhile,the induced radionuclide types have been studied. Recently,the linac mentioned above has been retired because of upgrading. The equipments and materials removed are used to study induced radioactivity generated in different materials. The research will provide the theoretical basis for the similar accelerator decommissioning plan,and is also significant for accelerator structure design,material selection and radiation protection programs design.