Background Nineteen undulators of various types are being fabricated for high-energy photon source(HEPS).In order to ensure the optical performance of the undulators,the girder deformation is usually carefully optimiz...Background Nineteen undulators of various types are being fabricated for high-energy photon source(HEPS).In order to ensure the optical performance of the undulators,the girder deformation is usually carefully optimized during the structural design stage.Purpose Optimization of magnet girder deformation is one of the key points to ensure undulator magneticfield performance.To reduce magnet girder deformation,base plate,feet and strong back should be designed carefully.In the HEPS undulator design and manufacturing stage,it is found that under special circumstances,such as after the height of the feet is adjusted,or after the undulator is lifted to other place,the base plate and girder may deform more than expected.Methods Therefore based on ANSYS simulation and experimental test results,the factors causing the deformation of the girders are carefully analyzed.Base plate and feet were optimized for different types of undulators to avoid girder deformation.Related simulation and laser tracker measurement were performed tofind out the reason in this paper.Results and conclusion Results show that the base plate of C-frame undulators will collapse and deform under the action of magnetic force.Asymmetric sagged base plate is the main reason of girder deformation.Increasing the thickness of the base plate and increasing the number of feet can both reduce that deformation.Optimization of magnet girder deformation is one of the key points to ensure undulator magneticfield performance.To reduce magnet girder deformation,base plate,feet and strong back should be designed carefully.展开更多
Purpose As the development of smaller accelerators technique,an X-band bi-period side-coupled accelerating structure has been designed for medical use.Methods The structure’s working frequency is 9.3 GHz.π/2 mode is...Purpose As the development of smaller accelerators technique,an X-band bi-period side-coupled accelerating structure has been designed for medical use.Methods The structure’s working frequency is 9.3 GHz.π/2 mode is chosen for the structure’s stability.There are 11 accelerating cells and 10 coupling cells,the first 5 of the accelerating cells work as non-light velocity part(βof the electron from 0.17 to 0.94),while the other 6 work as light velocity part.After CST simulation,the coupling constant between accelerating cells and coupling cells is 5%,and effi-cient shunt impedance is 142 MΩ/m.To feed power into the structure,a coupler is designed in the middle of the structure and the coupling coefficient is 1.4.Results After optimization,the particle’s capture efficiency is more than 30%,the particle energy is 2 MeV and the peak current is 60 mA,with the magnetron’s input power being 0.32 MW.Conclusion X-band side-coupled accelerator efficiency is high and is a more optimized design.This design is very meaningful for the development of smaller accelerators technique.展开更多
A cryogenic permanent magnet undulator prototype designed for Chinese High Energy Photon Source Test Facility(HEPSTF)at Institute of High Energy Physics is constructed and now commissioning.Motion precision of girders...A cryogenic permanent magnet undulator prototype designed for Chinese High Energy Photon Source Test Facility(HEPSTF)at Institute of High Energy Physics is constructed and now commissioning.Motion precision of girders is a significant parameter to guarantee gap error so as to avoid phase error and radiation intensity loss.In order to study and minimize girder parallelism errors,RADIA and SPECTRA are used to calculate qualified motion precision.Spring Modules and single motor closed-loop feedback are designed to compensate the errors.Magnetic field is finally tuned to reach specifications.Details of the study and analysis will be presented in this paper.展开更多
In this paper we report a compact and robust regenerative amplifier developed as the pump laser for a high repetition rate terahertz parametric amplifier.With properly chosen pump source and carefully designed cavity...In this paper we report a compact and robust regenerative amplifier developed as the pump laser for a high repetition rate terahertz parametric amplifier.With properly chosen pump source and carefully designed cavity,Nd∶YVO4 crystal,and laser beam collimator,a maximum output pulse energy of 480μJ has been achieved at the repetition rate of 10 kHz.The output laser has a nearly Gaussian transverse profile and a narrow bandwidth of 0.2 nm.Longterm monitoring shows an root mean square power fluctuation of about 1%.These characteristics satisfy all requirements for high repetition rate terahertz parametric amplifier.展开更多
文摘Background Nineteen undulators of various types are being fabricated for high-energy photon source(HEPS).In order to ensure the optical performance of the undulators,the girder deformation is usually carefully optimized during the structural design stage.Purpose Optimization of magnet girder deformation is one of the key points to ensure undulator magneticfield performance.To reduce magnet girder deformation,base plate,feet and strong back should be designed carefully.In the HEPS undulator design and manufacturing stage,it is found that under special circumstances,such as after the height of the feet is adjusted,or after the undulator is lifted to other place,the base plate and girder may deform more than expected.Methods Therefore based on ANSYS simulation and experimental test results,the factors causing the deformation of the girders are carefully analyzed.Base plate and feet were optimized for different types of undulators to avoid girder deformation.Related simulation and laser tracker measurement were performed tofind out the reason in this paper.Results and conclusion Results show that the base plate of C-frame undulators will collapse and deform under the action of magnetic force.Asymmetric sagged base plate is the main reason of girder deformation.Increasing the thickness of the base plate and increasing the number of feet can both reduce that deformation.Optimization of magnet girder deformation is one of the key points to ensure undulator magneticfield performance.To reduce magnet girder deformation,base plate,feet and strong back should be designed carefully.
基金Supported by National Natural Science Foundation of China(11275222).
文摘Purpose As the development of smaller accelerators technique,an X-band bi-period side-coupled accelerating structure has been designed for medical use.Methods The structure’s working frequency is 9.3 GHz.π/2 mode is chosen for the structure’s stability.There are 11 accelerating cells and 10 coupling cells,the first 5 of the accelerating cells work as non-light velocity part(βof the electron from 0.17 to 0.94),while the other 6 work as light velocity part.After CST simulation,the coupling constant between accelerating cells and coupling cells is 5%,and effi-cient shunt impedance is 142 MΩ/m.To feed power into the structure,a coupler is designed in the middle of the structure and the coupling coefficient is 1.4.Results After optimization,the particle’s capture efficiency is more than 30%,the particle energy is 2 MeV and the peak current is 60 mA,with the magnetron’s input power being 0.32 MW.Conclusion X-band side-coupled accelerator efficiency is high and is a more optimized design.This design is very meaningful for the development of smaller accelerators technique.
文摘A cryogenic permanent magnet undulator prototype designed for Chinese High Energy Photon Source Test Facility(HEPSTF)at Institute of High Energy Physics is constructed and now commissioning.Motion precision of girders is a significant parameter to guarantee gap error so as to avoid phase error and radiation intensity loss.In order to study and minimize girder parallelism errors,RADIA and SPECTRA are used to calculate qualified motion precision.Spring Modules and single motor closed-loop feedback are designed to compensate the errors.Magnetic field is finally tuned to reach specifications.Details of the study and analysis will be presented in this paper.
文摘In this paper we report a compact and robust regenerative amplifier developed as the pump laser for a high repetition rate terahertz parametric amplifier.With properly chosen pump source and carefully designed cavity,Nd∶YVO4 crystal,and laser beam collimator,a maximum output pulse energy of 480μJ has been achieved at the repetition rate of 10 kHz.The output laser has a nearly Gaussian transverse profile and a narrow bandwidth of 0.2 nm.Longterm monitoring shows an root mean square power fluctuation of about 1%.These characteristics satisfy all requirements for high repetition rate terahertz parametric amplifier.
