1. Design of BEPC Ⅱ Bunch Current Monitor System Zhanglei Beam Instrumentation Group

2. Bunch Current Monitor Monitor the bunch current in each bucket in Central Control room. Even injection and Bucket selection. Top off injection.

3. Related Parameters ParameterValue (colliding) Value (Synchrotron Radiation) unit RF frequency499.8 MHz Harmonic Number396402 Minimum Bunch Space 22ns Injection Rate50 Hz Beam total current910250mA Measurement Range 20 mA/bunch

4. System Distribution Front-end circuit near the storage ring. Bunch current data acquisition system at the Beam Local station. Bucket selection at the Central Control room.

5. System Distribution

6. Hardware CPU: MVME5100-0161 Powerpc604 ADC:ECAD2081500 8bits,1GHz Bandwidth,1.5Gsps sampling rate. Reflective Memory :GE Fanuc VMIVME5565. optical-linked. one placed in Beam Local station, and the other one placed in Central Control room.

7. Software Beam local station Acquiring real time bunch current data runs purely VxWorks Operating system. Bucket selection at the Central Control room runs also VxWorks Operating system. Opeartor interface of bunch current in each bucket runs EPICS I/O.

8. Front-end circuit

9. BPM at Electron Ring

10. BPM at Positron Ring

11. Output of Front-end circuit

12. Bunch Current Data Acquisition Located at Beam Local station. 1.5Gsps,1GHz bandwidth,8bits ADC 499.8*3 Sampling clk from BEPC Ⅱ Timing System. 50Hz trigger from BEPC Ⅱ Timing System 256 multi-turns average (Using Xilinx FPGA), 396*256 Bytes at Colliding Mode and 402*256 Bytes at Synchrotron Raditaion Mode. Sends digitized bunch current data to Reflective Memory every 50Hz trigger. VxWorks real time program.

13. ADC:ECAD2081500

14. Trigger and Clk to ADC

15. Program of Bunch Current Data Acquisition Two modes :Synchrotron Radiation and Colliding mode,402 and 396 buckets respectively. Synchrotron Radiation mode: only one ring. (Trigger  ADC  FPGA  Reflective Memory, single VxWorks task.) Colliding mode: two rings. (Trigger  ADC  FPGA  Reflective Memory, two VxWorks tasks. Semaphore controlled. )

16. Picture at Beam local Station

17. Bucket Selection at Central Control room Located at Central Control Room. receives bunch current data From Reflective Memory VMIVME5565. Bucket Selection and even Injection. VxWorks process

18. Picture at Bucket Selection

19. Operater Interface at Central Control room

20. Reference 1 M.J. Chin, J. A. Hinkson. PEP-II Bunch-by-Bunch Current Monitor. Proceedings of PAC1997: Vancouver, Canada, 1997.2235-2237 2 Yue Jun-Hui, Ma Li et al. HEP &NP, 2006, 30(2):163-165 (in Chinese) 3 E. Kikutani, A. Akiyama et al. Bucket Selection System of the KEKB Rings. Proceedings of APAC1998: Tsukuba, Japan, 1998.525-527 4 E. Kikutani, M.Suetake et al. Bucket Selector System for KEKB. Proceedings of ICA1999: Trieste, Italy, 1999.278-280 5 E. Kikutani, Y. Ogawa et al. Bucket Selection System-Recent Progress and the Plan In the Near Future. Proceedings of APAC2001: Beijing, China, 2001.669-671

21. Bunch Current Monitor