The Research And Developmentof High-speed Data Acquisition System For XAFS Station In SSRF

Shanghai synchrotron radiation facility(SSRF)is an advanced thirdgeneration light source,which is the first one in China.X-ray absorption fine structure spectroscopy(XAFS)experimental station is one of the first seven beamline stations in SSRF,which is the most widely used and most popular in SSRF.XAFS is an important analysis method of local structure of material research.It can provide the information of absorption geometry and electronic structure of atoms.It can also be used to characterize the structure and material characteristics.In recent years,the need for time resolved XAFS experimental method has increased year by year,especially in the field of energy materials.A complete absorption spectrum in conventional mode takes about 20 minutes to 1 hour.This method can obtain a high signal to noise ratio of the experimental data to meet the needs of the majority of users.However,due to the long scanning time,the process of the reaction system is unfavorable for the short time reaction in the observation.Therefore,it is necessary to develop a high-speed data acquisition system.On the one hand,it provides a powerful tool for the study of the physical and chemical processes of second order.On the other hand,it can reduce the radiation damage of synchrotron radiation light to the sample,and it has a wide range of applications in the field of catalysis,environment and so on.In this work,the high-speed data acquisition system is made by preserving the existing conventional XAFS data acquisition system,modifying some key hardware,writing programs and developing user interface with LabVIEW.It can get a completely spectrum in a second time scale.In this work,the whole system is done offline and online testing using standard and experimental samples.It shows that this highspeed data acquisition system is stable and reliable and it achieves the desired goal.The whole process of the development of high-speed data acquisition system at XAFS station in SSRF includes the following aspects: 1.The feasibility analysis and system design.According to the existing hardware condition of the experimental station and the stability and response speed of the monochromator,the ionization chambers,the current amplifiers and the data acquisition card,the time scale of the high-speed data acquisition is determined in the second order.The overall design scheme is increase of high-speed data acquisition card based on important devices retention to achieve the goal system.2.The selection of hardware and equipment debugging.According to the requirements of high-speed,synchronism and compatibility,the data acquisition equipment is selected and the hardware scheme of PXI system is determined.3.The software design and programming.LabVIEW software interface is friendly,easy to operate,short development cycle and other characteristics.It is used as a data acquisition development environment and user interface.Comparing different data sharing methods,DSC module is used to share data between EPICS and labVIEW.4.The system testing and user experiment.After the whole system is set up,the parameters of the system which are stability,repeatability,signal to noise ratio,are tested and selected.In addition,time resolved experiments were performed using the user samples.It shows that a highspeed data acquisition system with time resolution is developed,which can achieve the expected goal.