Design of BEPC Bunch Current Monitor ⅡSystem

ZhangleiBeam Instrumentation Group

Bunch Current Monitor

• Monitor the bunch current in each bucket in Central Control room.

• Even injection and Bucket selection.• Top off injection.

Related ParametersParameter Value

(colliding)Value

(Synchrotron Radiation)

unit

RF frequency 499.8 499.8 MHzHarmonic Number 396 402

Minimum Bunch Space

2 2 ns

Injection Rate 50 50 HzBeam total current 910 250 mAMeasurement

Range20 20 mA/bunch

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.

System Distribution

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.

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.

Front-end circuit

BPM at Electron Ring

BPM at Positron Ring

Output of Front-end circuit

Bunch Current Data Acquisition • Located at Beam Local station.• 1.5Gsps,1GHz bandwidth ,8bits ADC• 499.8*3 Sampling clk from BEPC Timing SystⅡ

em.• 50Hz trigger from BEPC Timing SystemⅡ• 256 multi-turns average (Using Xilinx FPGA), 39

6*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.

ADC:ECAD2081500

Trigger and Clk to ADC

Program of Bunch Current Data Acquisition

• Two modes :Synchrotron Radiation and Colliding mode,402 and 396 buckets respectively.

• Synchrotron Radiation mode: only one ring. (TriggerADC FPGAReflective Memory, single VxWorks task.)

• Colliding mode: two rings. (Trigger ADC FPGA Reflective Memory, two VxWorks tasks. Semaphore controlled. )

Picture at Beam local Station

Bucket Selection at Central Control room

• Located at Central Control Room.• receives bunch current data From Reflecti

ve Memory VMIVME5565.• Bucket Selection and even Injection.• VxWorks process

Picture at Bucket Selection

Operater Interface at Central Control room

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 Chin

ese)• 3 E. Kikutani, A. Akiyama et al. Bucket Selection System of the KEK

B 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

Bunch Current Monitor