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Liu, L.

Paper Title Page
MPPE041 Orbit Stability at the Brazilian Synchrotron Light Source 2687
 
  • L. Liu, P.F. Tavares
    LNLS, Campinas
 
  A task force has been implemented at the Brazilian Synchrotron Light Laboratory to improve the beam orbit stability in the 1.37 GeV electron storage ring. The main problems faced during this year (2004) were due to the installation of a second RF cavity in the machine. We describe the main problems and the solutions that were implemented.  
WPAE007 Commissioning of the LNLS 2 T Hybrid Wiggler 1072
 
  • R.H.A. Farias, J.F. Citadini, M.J. Ferreira, J.G.R.S. Franco, A.F.A. Gouveia, L.C. Jahnel, L. Liu, R.T. Neuenschwander, X.R. Resende, P.F. Tavares, G. Tosin
    LNLS, Campinas
  • N.P. Abreu
    UNICAMP, Campinas, São Paulo
 
  Funding: MCT-CNPq, FAPESP.

We present the results of the commissioning of a 28-pole 2 T Hybrid Wiggler at the 1.37 GeV electron storage ring of the Brazilian Synchrotron Light Source. The wiggler will be used mainly for protein crystallography and was optimized for the production of 12 keV photons. The very high field and relatively large gap (22 mm) of this insertion device led to a magnetic design that includes large main and side magnets and heavily saturated poles. We present the results of the commissioning with beam, with special attention to the correction of the large linear tune-shift perturbations produced by the wiggler as well as on the reduction of beam lifetime at full energy. Since the injection at the LNLS storage ring is performed at 500 MeV we also focus on the effects of non-linearities and their impact on injection efficiency.

 
WOAB010 BUNCH TRACING BY BUNCH BY BUNCH MEASUREMENT SYSTEM IN HLS 719
 
  • K. Zheng, W. Li, J.H. Liu, L. Liu, B. Sun, J.H. Wang, Y.L. Yang
    USTC/NSRL, Hefei, Anhui
 
  Funding: Supported by National Natural Science Project (10175063)

In this paper, we introduce a bunch tracing system which is based on a bunch-by-bunch (BxB) measurement system in Hefei Light Source (HLS), and present the analysis of the experiment results. Using an in-phase gate signal and a double balance mixer to control an external trigger of ADC, we test the reliability of the BxB system. By this system, we can trace all marked bunches in a set time slot or in manual burst mode. We can record all bunches’ data during the injection, ramping, wiggler excitation and normal operation, and provide a powerful facility for machine study.

 
RPAE076 The Commission of Hefei Light Source After Reconstruction 3967
 
  • H. Xu, H. He, W. Li, G. Liu, L. Liu, S. Shang, B. Sun, L. Wang
    USTC/NSRL, Hefei, Anhui
 
  After the new four-kicker injection bump system was mounted, it was found that the magnetic field of four–kicker magnet through the same pulse current is different each other, the reason is which the width of pulse magnet fields is not same, so the four-kickers can not form completely local bump, and produce large global orbit distortion,and lead to beam loss. At last we found that the films of ceramic chambers were not plated evenly. The new rf system have two low level control circle circuits, which are the frequency and amplitude automatic adjustment systems. Because the energy of injection electron beam is 200MeV, and radiation damping is weak, so the gain of amplitude circuit was adjusted to the small value not to disturb beam.The beam load is large,and Robinson instability happen easily, so the small detune angle is preset. The Octupoles were inserted in ring for damping instability, and over compensated chromaticity was adjusted.Superconductor wiggler bring the variation of beta function, and the beam life time decreased from 8 hours to about 3 hours. By adjusting the beta functions close to situation ago, the beam lifetime was improved.  
RPPT047 Development of Measurement and Transverse Feedback System at HLS 2974
 
  • J.H. Wang, H. He, W. Li, J.H. Liu, L. Liu, B. Sun, Y.L. Yang, K. Zheng, Z.R. Zhou
    USTC/NSRL, Hefei, Anhui
 
  In order to observe and cure coupled bunch (CB) instabilities caused by the high order modes (HOMs) of the RF cavity and the resistive wall impedance of the Ring vacuum chamber, which were ineluctable during the operation of the accelerator, an observer system characterized by bunch by bunch measurement of transverse ßoscillation and longitudinal synchrotron phase oscillation has been constructed and commissioned at Hefei Light Source (HLS); meanwhile a transverse bunch-by-bunch feedback system is under construction. The design and development of the systems, as well as diagnostics results of machine instabilities will be presented in this paper.  
RPPT048 HLS Turn-By-Turn System and Its Application 3022
 
  • J.H. Wang, W. Li, J.H. Liu, L. Liu, B. Sun, Y.L. Yang, K. Zheng
    USTC/NSRL, Hefei, Anhui
 
  Design and experimental application of the turn-by-turn system of Hefei Light Source (HLS) are presented in this paper. The front-end signal measurement adopts a log-ratio electronics circuitry. The system is designed to be capable of up to 2 seconds data acquisition. Injection kickers are used to excite beam for monitoring ß oscillation and damping rate. Some of experimental applications are also illustrated, in commission of both the upgraded injection system of HLS and the lower frequency feedback system. The results shows that in order to improve the accumulation of the injected beam, it is very necessary to investigate integral magnet fields equilibrium of injected system and proper measures to control restrain remnants ß-oscillation caused by the injected system error.  
RPPT050 The Measurement of Tune and Phase Space at HLS 3114
 
  • Y.L. Yang, J.H. Liu, L. Liu, B. Sun, J.H. Wang, K. Zheng
    USTC/NSRL, Hefei, Anhui
 
  Tune and phase space online monitor at the electronic storage ring of Hefei Light Source (HLS) have been realized by using of turn-by-turn beam position data. In this paper, we have compared many methods to compute tune and discussed how to choose the best fitting method for our online tune computing. We can compute and display tune online, at the same time, beam tracks were obtained on the transverse phase space by using turn-by-turn beam position data at two differently-located beam-position-monitor electrodes. With these instruments we can precise and attractive study machine instabilities