Embedded EPICS Based Beam Loss Monitor System Of HLS-Ⅱ

A new beam loss monitor system based on embedded EPICS is developed for the top-offfupgrade of HLS-Ⅱ,to monitor the position and value of beam loss of storage ring.Hefei light source after two period of upgrading,increase the focus on the horizontal direction,the beam emittance greatly reduced,light stability is obviously improved.Toschek effect increases with the decrease of emittance,which leads to the increase of beam loss.The electron shower signals are obtained by the double PIN photodiode detectors around the storage ring,then acquired by the new BLM processors,where the beam loss signals are analysed and distributed to the accelerator control network,by embedded EPICS on embedded Linux system of the BLM processors,and the beam loss data could be obtained in the central control room.The new BLM system could to do the self-checking function to the double PIN photodiode detectors,to eliminate hidden malfunction of the detectors,and to improve stability and reliability of the whole system.Meanwhile,the reason of the beam losses,beam life and radiation type are been analyzed.In the design of beam loss monitoring equipment,the design size of beam loss monitoring equipment is determined according to the actual installation location space of storage ring.Then,according to the functions needed by the beam loss monitoring equipment,analog-to-digital conversion circuit,power supply circuit,signal process-ing circuit,MCU chip monitoring circuit,data communication circuit,self-test circuit and so on are designed.The beam loss monitoring system designed in this paper has two modes:measurement mode and self-inspection mode.The difference between the two modes lies in switching the output signal of the double PIN photodiode.In the measurement mode,the output signal of the double PIN photodiode is the beam loss signal;in the self-test mode,the output signal of the double PIN photodiode is a fixed frequency value.The reliability of the system operation is improved by comparing to judge whether the beam loss equipment is working properly.There are three kinds of data output modes for beam loss monitoring equipment,namely serial port output,touch screen display and network transmission.The three data output modes are suit-able for debugging,off-line testing and on-line testing,which can greatly improve the test flexibility of equipment.The structure of EPICS system can be directly connected to the control system of Hefei Light Source,which simplifies the system structure and improves the stability of the system.After trial operation,the beam loss data in Decay mode,Injection mode and Top-off mode of Hefei Light Source are observed.The results show that the new BLM system can meet the constant current operation requirements of the top-off upgrade of HLS-Ⅱ.