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Sun, B.

Paper Title Page
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.  
RPAT090 The Study of New Signal Processing Technique in Photon Beam Position Monitors 4239
 
  • S.F. Lin, H. Gao, P. Lu, B. Sun, J. Wang
    USTC/NSRL, Hefei, Anhui
 
  A log-ratio signal processing technique in photon beam position monitors (PBPM) was presented in this paper. The main performances (e.g. sensitivity, position offset and linearity range) of split PBPM and a pair of wires PBPM were analyzed , and the result of the measurement fit well with the theory. An inexpensive logarithmic amplifier chip which can measure photon currents from 0.1nA to 3.5mA was used in electronic circuits. The logarithmic ratio of the signal amplitudes from the PBPM provides a real-time analog signal that has wider linearity range and higher bandwidth than signal processing technique.

Supported by Natural Science Foundation of China (10275062) and CAS Knowledge Innovation Project (KY4206).

 
RPPT045 A Method to Calibrate Beam Position Monitor at HLS 200 MeV LINAC 2896
 
  • J.-H. Li, Y. Cao, H. He, K. Jin, P. Lu, B. Sun, J. P. Wang, Y. Wang, P. Zheng
    USTC/NSRL, Hefei, Anhui
 
  In order to improve injection efficiency of HLS 200Mev LINAC, we redesign a new strip line beam position monitor system, which is consisted of a strip line structure and a signal processing system. We decide on an online calibration method based on beam to find out the geometry centre displacement and relative gain offset. Before the BPM testing bench has been prepared, we make a simulation based on the model accounted for all factors influencing signal amplitudes and get the calibrating results. At last, we analyze the nonlinearity effect on the calibration results.  
RPPT046 Development and Application of Bunch-by-Bunch Measurement System of HLS 2932
 
  • J.H. Liu, Y.J. Pei, B. Sun, J.H. Wang, Y.L. Yang, K. Zheng
    USTC/NSRL, Hefei, Anhui
 
  This paper is intended to present the newly implemented wideband (100MHz) bunch oscillation measurement system, which is in nature a different method from the narrow-band (<5MHz) facilities employed before. Basic formalism and implementation details of the system is introduced to illustrate the function of observing coupled bunch instabilities in time and frequency domain. The designed function includes detecting of transverse oscillation, synchrotron phase oscillation, as well as bunch filling pattern. Some diagnostics results of machine instabilities and application of this system are also discussed.  
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