Research On Key Technology Of Wire Scanner System For High Repetition Frequency FEL Facility

Shanghai HIgh repetition rate XFEL a Nd Extreme light facility(SHINE)accelerates electrons to 8Ge V by cryogenic superconducting high-frequency cavities,and its repetition rate can up to 1MHz.For beam profile measurement of SHINE,micro interception beam profile measurement method is needed,because the number of secondary particles produced in this way is much smaller than interception measurement method,such as profile target.It can greatly reduce the risk of quench of superconducting cavity aim to improve system security during operation of system,and can also measure beam profile without affecting beam operation.Based on the beam motion law of linac,this paper compares various beam profile measurement methods,and comes to the conclusion that wire scanner system as a micro interception method is suitable for high repetition free electron laser.After a detailed investigation of the application of wire scanner system in accelerators around the world,focusing on the main international free electron lasers,combined with the actual situation of SHINE,and using knowledge of physical theory,mechanical design,signal processing and circuit design,simulation of the relevant parameters on wire scanner system,physical design of wire scanner probe,mechanical design,development of beam loss monitor and beam experiment are completed.The ANSYS finite element analysis software is used to simulate the interaction between wire scanner probe and beam in wide parameter range.The empirical formula for calculating the maximum temperature of tungsten wire is presented.The results of force and deformation of the probe during operation of wire scanner system are obtained.FLUKA is used base on Monte Carlo principle to carried out simulation analysis in a wide range of parameters.The distribution of particles downstream of the interaction point between wire scanner probe and beam is obtained,and the empirical formula of installation position of beam loss monitor is presented.The electronic design of wire scanner system is developed by design of RF acquisition board and digital carrier and software development is preliminarily completed.The function verification is finished in laboratory.Finally,the prototype of the wire scanner system is installed in Shanghai soft X-ray Free Electron Laser(SXFEL).The system has been installed and beam experimental platform has been built.Measurement of beam size of micro interception on SXFEL is realized.Also we finish analyzing the experimental data and evaluating system performance.It lays a good technical foundation for construction of SHINE.