Research On Key Technologies Of Machine Protection System Of CAFe

In the current context of growing energy needs and concerns for the environmental pollution,it is important to develop affordable and environmentally responsible energy technologies.Nuclear power has the potential to meet future generations’ energy needs in sustainable way and in long term scenarios.As one of the clean nuclear technologies,an accelerator driven sub-critical(ADS)system may be employed in the field of nuclear power to address several missions,including transmutation of long-lived radio-nuclides in radioactive waste into short-lived radio-nuclides or stable isotopes,generating electricity and/or processing heat.An ADS system consists of a high-power proton accelerator,a spallation target and a sub-critical reactor.In order to resolve the key technologies in the high-power proton accelerator,the China ADS Front-end Demo linac(CAFe),a prototype superconducting proton linear accelerator,has been developed in the Institute of Modern Physics,Chinese Academy of Sciences.This thesis focuses on the key technologies in the machine protection system(MPS)which is used in the control system for CAFe accelerator.In particular,the following three key technologies have been studied,i.e.the high precision time-stamp technology for the post-mortem data analysis in MPS,the control technology of timing sequence for MPS,and the integration of controllers in MPS.Firstly,in the postmortem analysis process,the time resolution of malfunction realized by the software system is in the order of milliseconds,while the frequency of CAFe accelerator cavity is 162.5MHz,the time structure of beam cluster is about 6ns and the time resolution of fault signals detected by beam position detection and beam loss detection in the beam measurement system is also in the order of microseconds.If the time scale technology based on system software is adopted,its time resolution cannot provide detailed data used to describe event process for the experimenters,and cannot accurately restore the fault scene and the sequence of fault events.To solve this problem,a method to provide high precision time stamp for machine protection system is proposed.Based on the TAI clock and distributed clock synchronization technology in the White Rabbit(WR)system,this thesis studies the high precision time-stamp technology which ensures the time mark of the fault signals of each device,and a timestamping precision of 4 ns has been attained.Secondly,this thesis studies the control technology of timing sequence in MPS.In the actual operation process,the action control method of the equipment is single,and the control timing sequence cannot be set flexibly.Thus,it is easy for the equipment to be damaged.For example,if the proton beam is not yet switched off by the LEBT Chopper when the valve of the vacuum system is closed or the relevant plug-in components of other systems is plugged in the beam tube,these plug-in components will be directly bombarded by the beam.In serious cases,they will be instantly broken down,resulting in vacuum breaking and the environmental deterioration for the superconducting cavities.To resolve this problem,a control method of timing sequence in the actual operation process has been proposed.Furthermore,by transferring part of the timing control function of timing sequence realized by the original PLC hardware platform to the FPGA controller,the ability to adjust timing relationship online is improved.This adjustment function of timing relationship has been tested experimentally.The experimental measurement result indicates that the developed method improves the flexibility and reliability of the system.Finally,this thesis develops an integration method of the controllers used in MPS.By analyzing the controllers installed in the FPGA devices and the control functions in the PC,the developed method is to integrate the control functions in the PC into the FPGA devices.Then,some functions in EPICS(Experimental Physics and Industrial Control System)software tool has also been embedded into the FPGA devices.Thus,the process variables(PV)used in the EPICS framework can also be read out in the local control system.The developed integration technology makes it possible to use intelligent controllers in MPS.In summary,after having analyzed the key technical problems in the operation of the high-power proton accelerator,this thesis studies the high-precision time-stamp system,the control technology of timing sequence and the technology of embedded controllers.The developed timestamp system with a precision of nanosecond can be used for the post-mortem data analysis in MPS.Based on the event trigger mode in the FPGA controllers,the functions for the on-line modification of control timing sequence have been studied.By integrating the functions of FPGA devices with that of the industrial personal computers,the developed embedded controllers provide a technical solution for the large-scale deployment of intelligent front-end controllers.