在高强度X射线辐照下,X射线自由电子激光(X-ray Free-electron Laser,XFEL)装置的光学元件薄膜产生的大量辐照缺陷会导致材料结构损伤,引起宏观性能退化,从而影响其服役寿命,进而影响到XFEL装置的可靠性和稳定性。为了研究材料辐照缺陷...在高强度X射线辐照下,X射线自由电子激光(X-ray Free-electron Laser,XFEL)装置的光学元件薄膜产生的大量辐照缺陷会导致材料结构损伤,引起宏观性能退化,从而影响其服役寿命,进而影响到XFEL装置的可靠性和稳定性。为了研究材料辐照缺陷过程以及方便耐辐照材料的数据积累,提供了一种基于Python语言的自动化辐照模拟程序AISL(Automatic Irradiation Simulation based on LAMMPS),以支持采用分子动力学方法模拟XFEL对材料的辐照损伤进行微观研究。AISL实现了模拟任务的自动化工作流管道,包括高通量计算任务的管理和执行,计算数据的高可靠存储和热力学信息的后处理。基于AISL在XFEL光学元件金属薄膜辐照损伤模拟的应用实例研究,表明了AISL是一种便捷开展高通量自动化的辐照模拟研究的有效方法,能够显著提高基于LAMMPS的材料辐照损伤模拟计算效率。展开更多
The linac based XFEL and ERL are advanced （or, say, 4th generation） light sources, with different electron beam parameters and different advantages. However, the linac used for XFEL and ERL should provide very advan...The linac based XFEL and ERL are advanced （or, say, 4th generation） light sources, with different electron beam parameters and different advantages. However, the linac used for XFEL and ERL should provide very advanced beams with high energy, high peak and/or average current, very low emittance and low energy spread, thus making the linac very complicated and expensive. To share the XFEL and ERL advantages and save the construction-operation budget, a proposal of using a common superconducting electron linac for hard X-ray XFEL and ERL is described in this paper. The interactions between the XFEL and ERL beams via the accelerating structure are studied and the result is positive.展开更多
The third harmonic superconducting cryomodule is being designed for the Shanghai High repetition rate XFEL and Extreme light facility(SHINE)project,which is under construction.In contrast to the European X-ray Free El...The third harmonic superconducting cryomodule is being designed for the Shanghai High repetition rate XFEL and Extreme light facility(SHINE)project,which is under construction.In contrast to the European X-ray Free Electron Laser(E-XFEL)project,the 3.9 GHz cryomodules in the SHINE project will operate in the continuous wave regime with higher radio frequency average power for both cavities and couplers.We propose a 3.9 GHz fundamental power coupler with an adjustable antenna length,for satisfying the SHINE project requirements.Here,we describe the 3.9 GHz fundamental power coupler's design considerations and power requirements for various operating modes of the SHINE Linac.We also present the results of the radio frequency simulation and optimization,including the studies on multipacting and thermal analysis of the proposed 3.9 GHz coupler.展开更多
A corrugated structure is built and tested on many FEL facilities,providing a'dechirper'mechanism for eliminating energy spread upstream of the undulator section of X-ray FELs.The wakefield effects are here st...A corrugated structure is built and tested on many FEL facilities,providing a'dechirper'mechanism for eliminating energy spread upstream of the undulator section of X-ray FELs.The wakefield effects are here studied for the beam dechirper at the Shanghai high repetition rate XFEL and extreme light facility(SHINE),and compared with analytical calculations.When properly optimized,the energy spread is well compensated.The transverse wakefield effects are also studied,including the dipole and quadrupole effects.By using two orthogonal dechirpers,we confirm the feasibility of restraining the emittance growth caused by the quadrupole wakefield.A more efficient method is thus proposed involving another pair of orthogonal dechirpers.展开更多
We present new diagnostics for use in optical laser pump-X-ray Free Electron Laser(XFEL)probe experiments to monitor dimensions,intensity profile and focusability of the XFEL beam and to control initial quality and ho...We present new diagnostics for use in optical laser pump-X-ray Free Electron Laser(XFEL)probe experiments to monitor dimensions,intensity profile and focusability of the XFEL beam and to control initial quality and homogeneity of targets to be driven by optical laser pulse.By developing X-ray imaging,based on the use of an LiF crystal detector,we were able to measure the distribution of energy inside a hard X-ray beam with unprecedented high spatial resolution(~1 mm)and across a field of view larger than some millimetres.This diagnostic can be used in situ,provides a very high dynamic range,has an extremely limited cost,and is relatively easy to be implemented in pump-probe experiments.The proposed methods were successfully applied in pump-probe experiments at the SPring-8 Angstrom Compact free electron LAser(SACLA)XFEL facility and its potential was demonstrated for current and future High Energy Density Science experiments.展开更多
The main “bottleneck” limiting the beam power in circular machines is caused by space charge effects that produce beam instabilities. To increase maximally the beam power of a “proton driver”, it is proposed to bu...The main “bottleneck” limiting the beam power in circular machines is caused by space charge effects that produce beam instabilities. To increase maximally the beam power of a “proton driver”, it is proposed to build a facility consisting solely of a 2.5 GeV injector linac (PI) and a 20 GeV pulsed superconducting linac (SCL). Such a facility could be constructed using the existing KEK accelerator infrastructure. The PI, based on the European Spallation Source (ESS) linac, would serve both as an injector to the SCL and a source of proton beams that could be used to copiously produce, e.g., muons and “cold” neutrons. Protons accelerated by the SCL would be transferred through the KEK Tristan ring in order to create neutrino, kaon and muon beams for fixed-target experiments. At a later stage, a 70 GeV proton synchrotron could be installed inside the Tristan ring. The SCL, comprising 1.3 GHz ILC-type rf cavities, could also accelerate polarized or unpolarized electron beams. After acceleration, electrons could be used to produce polarized positrons, or may traverse an XFEL undulator.展开更多
In this paper,a simple theoretical model combining Monte Carlo simulation with the enthalpy method is provided to simulate the damage resistance of B4C/Si-sub mirror under X-ray free-electron laser irradiation.Two dif...In this paper,a simple theoretical model combining Monte Carlo simulation with the enthalpy method is provided to simulate the damage resistance of B4C/Si-sub mirror under X-ray free-electron laser irradiation.Two different damage mechanisms are found,dependent on the photon energy.The optimum B4C film thickness is determined by studying the dependence of the damage resistance on the film thickness.Based on the optimized film thickness,the damage thresholds are simulated at photon energy of 0.4-25 keV and a grazing incidence angle of 2 mrad.It is recommended that the energy range around the Si K-edge should be avoided for safety reasons.展开更多
Bunch compressor is widely used in free electron laser facility.The normalized emittance dilution comes from the high order magnet components and the misalignment of dipole.This paper describes the tolerance study for...Bunch compressor is widely used in free electron laser facility.The normalized emittance dilution comes from the high order magnet components and the misalignment of dipole.This paper describes the tolerance study for the CTF first bunch compressor.展开更多
In order to study the dynamic response of the material and the physical mechanism of fluid dynamics, an accelerator scenario which can be applied to both hard X-ray free electron laser and high energy electron radiogr...In order to study the dynamic response of the material and the physical mechanism of fluid dynamics, an accelerator scenario which can be applied to both hard X-ray free electron laser and high energy electron radiography is proposed. This accelerator is mainly composed of a 12 GeV linac, an undulator branch and an eRad beamline. In order to characterize a sample＇s dynamic behavior in situ and real-time with XFEL and eRad simultaneously, the linac should be capable of accelerating the two kinds of beam within the same operation mode. Combining in-vacuum and tapering techniques, the undulator branch can produce more than 10zl photons per pulse in 0.1% bandwidth at 42 keV. Finally, an eRad amplifying beamline with 1：10 ratio is proposed as an important complementary tool for the wider view field and density identification ability.展开更多
In North China, there is a preliminary proposal for ERL-FEL light source （BXERL-FEL） with its aim at ＂one machine, two purposes＂ （the XFEL and ERL work simultaneously）. One of the key technologies is the merger ...In North China, there is a preliminary proposal for ERL-FEL light source （BXERL-FEL） with its aim at ＂one machine, two purposes＂ （the XFEL and ERL work simultaneously）. One of the key technologies is the merger section. In this paper, we give the physical design of the merger section for BXERL-FEL which merges three kinds of electron beam.展开更多
With the development of the XFEL （X-ray free electron laser）, high quality diffraction patterns from nanocrystals have been achieved. The nanocrystals with different sizes and random orientations are injected to the...With the development of the XFEL （X-ray free electron laser）, high quality diffraction patterns from nanocrystals have been achieved. The nanocrystals with different sizes and random orientations are injected to the XFEL beams and the diffraction patterns can be obtained by the so-called ＂diffraction-and-destruction＂ mode. The recovery of orientations is one of the most critical steps in reconstructing the 3D structure of nanocrystals. There is already an approach to solve the orientation problem by using the automated indexing software in crystallography. However, this method cannot distinguish the twin orientations in the cases of the symmetries of Bravais lattices higher than the point groups. Here we propose a new method to solve this problem. The shape transforms of nanocrystals can be determined from all of the intensities around the diffraction spots, and then Fourier transformation of a single crystal cell is obtained. The actual orientations of the patterns can be solved by comparing the values of the Fourier transformations of the crystal cell on the intersections of all patterns. This so-called ＂multiple-common-line＂ method can distinguish the twin orientations in the XFEL diffraction patterns successfully.展开更多
In the proposal of the Beijing Advanced Light Source, a compact combination of XERL and XFEL using a common SC linac is being considered. In the meantime, an ERL-FEL test facility is being proposed and will be used fo...In the proposal of the Beijing Advanced Light Source, a compact combination of XERL and XFEL using a common SC linac is being considered. In the meantime, an ERL-FEL test facility is being proposed and will be used for THz radiation. In this test facility, a L-band photocathode RF injector is needed. In this paper, we give the physical design of the L-band photocathode RF injector for the test facility.展开更多
文摘在高强度X射线辐照下,X射线自由电子激光(X-ray Free-electron Laser,XFEL)装置的光学元件薄膜产生的大量辐照缺陷会导致材料结构损伤,引起宏观性能退化,从而影响其服役寿命,进而影响到XFEL装置的可靠性和稳定性。为了研究材料辐照缺陷过程以及方便耐辐照材料的数据积累,提供了一种基于Python语言的自动化辐照模拟程序AISL(Automatic Irradiation Simulation based on LAMMPS),以支持采用分子动力学方法模拟XFEL对材料的辐照损伤进行微观研究。AISL实现了模拟任务的自动化工作流管道,包括高通量计算任务的管理和执行,计算数据的高可靠存储和热力学信息的后处理。基于AISL在XFEL光学元件金属薄膜辐照损伤模拟的应用实例研究,表明了AISL是一种便捷开展高通量自动化的辐照模拟研究的有效方法,能够显著提高基于LAMMPS的材料辐照损伤模拟计算效率。
文摘The linac based XFEL and ERL are advanced （or, say, 4th generation） light sources, with different electron beam parameters and different advantages. However, the linac used for XFEL and ERL should provide very advanced beams with high energy, high peak and/or average current, very low emittance and low energy spread, thus making the linac very complicated and expensive. To share the XFEL and ERL advantages and save the construction-operation budget, a proposal of using a common superconducting electron linac for hard X-ray XFEL and ERL is described in this paper. The interactions between the XFEL and ERL beams via the accelerating structure are studied and the result is positive.
基金supported by Shanghai Municipal Science and Technology Major Project(No.2017SHZDZX02)。
文摘The third harmonic superconducting cryomodule is being designed for the Shanghai High repetition rate XFEL and Extreme light facility(SHINE)project,which is under construction.In contrast to the European X-ray Free Electron Laser(E-XFEL)project,the 3.9 GHz cryomodules in the SHINE project will operate in the continuous wave regime with higher radio frequency average power for both cavities and couplers.We propose a 3.9 GHz fundamental power coupler with an adjustable antenna length,for satisfying the SHINE project requirements.Here,we describe the 3.9 GHz fundamental power coupler's design considerations and power requirements for various operating modes of the SHINE Linac.We also present the results of the radio frequency simulation and optimization,including the studies on multipacting and thermal analysis of the proposed 3.9 GHz coupler.
基金supported by the Youth Innovation Promotion Association CAS(Nos.2018300 and 2021282)the National Key Research and Development Program of China(No.2018YFE0103100)the National Natural Science Foundation of China(No.11935020)。
文摘A corrugated structure is built and tested on many FEL facilities,providing a'dechirper'mechanism for eliminating energy spread upstream of the undulator section of X-ray FELs.The wakefield effects are here studied for the beam dechirper at the Shanghai high repetition rate XFEL and extreme light facility(SHINE),and compared with analytical calculations.When properly optimized,the energy spread is well compensated.The transverse wakefield effects are also studied,including the dipole and quadrupole effects.By using two orthogonal dechirpers,we confirm the feasibility of restraining the emittance growth caused by the quadrupole wakefield.A more efficient method is thus proposed involving another pair of orthogonal dechirpers.
基金The XFEL experiments were performed at the BL3 of SACLA with the approval of the Japan Synchrotron Radiation Research Institute(JASRI)(Proposals Nos.2014A8045,and 2014B8068)This research was partially supported by grants from Grants-in-Aid for Scientific Research(Kakenhi Grant Nos.15H02153 and 17K05729)+1 种基金the Core-to-Core Program on International Alliance for Material Science in Extreme States with High Power Laser of the Japan Society for the Promotion of Science(JSPS),from the X-ray Free Electron Laser Priority Strategy Program of the MEXT,contract 12005014,and within the state assignment of FASO of Russia(theme N01201357846)The part of work was supported by the Agence Nationale de la Recherche in the frame of the ANR project TurboHEDP(ANR-15-CE30-0011).
文摘We present new diagnostics for use in optical laser pump-X-ray Free Electron Laser(XFEL)probe experiments to monitor dimensions,intensity profile and focusability of the XFEL beam and to control initial quality and homogeneity of targets to be driven by optical laser pulse.By developing X-ray imaging,based on the use of an LiF crystal detector,we were able to measure the distribution of energy inside a hard X-ray beam with unprecedented high spatial resolution(~1 mm)and across a field of view larger than some millimetres.This diagnostic can be used in situ,provides a very high dynamic range,has an extremely limited cost,and is relatively easy to be implemented in pump-probe experiments.The proposed methods were successfully applied in pump-probe experiments at the SPring-8 Angstrom Compact free electron LAser(SACLA)XFEL facility and its potential was demonstrated for current and future High Energy Density Science experiments.
文摘The main “bottleneck” limiting the beam power in circular machines is caused by space charge effects that produce beam instabilities. To increase maximally the beam power of a “proton driver”, it is proposed to build a facility consisting solely of a 2.5 GeV injector linac (PI) and a 20 GeV pulsed superconducting linac (SCL). Such a facility could be constructed using the existing KEK accelerator infrastructure. The PI, based on the European Spallation Source (ESS) linac, would serve both as an injector to the SCL and a source of proton beams that could be used to copiously produce, e.g., muons and “cold” neutrons. Protons accelerated by the SCL would be transferred through the KEK Tristan ring in order to create neutrino, kaon and muon beams for fixed-target experiments. At a later stage, a 70 GeV proton synchrotron could be installed inside the Tristan ring. The SCL, comprising 1.3 GHz ILC-type rf cavities, could also accelerate polarized or unpolarized electron beams. After acceleration, electrons could be used to produce polarized positrons, or may traverse an XFEL undulator.
基金supported by the National Natural Science Foundation of China(NSFC)(No.11875203)。
文摘In this paper,a simple theoretical model combining Monte Carlo simulation with the enthalpy method is provided to simulate the damage resistance of B4C/Si-sub mirror under X-ray free-electron laser irradiation.Two different damage mechanisms are found,dependent on the photon energy.The optimum B4C film thickness is determined by studying the dependence of the damage resistance on the film thickness.Based on the optimized film thickness,the damage thresholds are simulated at photon energy of 0.4-25 keV and a grazing incidence angle of 2 mrad.It is recommended that the energy range around the Si K-edge should be avoided for safety reasons.
文摘Bunch compressor is widely used in free electron laser facility.The normalized emittance dilution comes from the high order magnet components and the misalignment of dipole.This paper describes the tolerance study for the CTF first bunch compressor.
基金Supported by China Academy of Engineering Physics(2014A0402016)Institute of Fluid Physics(SFZ20140201)
文摘In order to study the dynamic response of the material and the physical mechanism of fluid dynamics, an accelerator scenario which can be applied to both hard X-ray free electron laser and high energy electron radiography is proposed. This accelerator is mainly composed of a 12 GeV linac, an undulator branch and an eRad beamline. In order to characterize a sample＇s dynamic behavior in situ and real-time with XFEL and eRad simultaneously, the linac should be capable of accelerating the two kinds of beam within the same operation mode. Combining in-vacuum and tapering techniques, the undulator branch can produce more than 10zl photons per pulse in 0.1% bandwidth at 42 keV. Finally, an eRad amplifying beamline with 1：10 ratio is proposed as an important complementary tool for the wider view field and density identification ability.
文摘In North China, there is a preliminary proposal for ERL-FEL light source （BXERL-FEL） with its aim at ＂one machine, two purposes＂ （the XFEL and ERL work simultaneously）. One of the key technologies is the merger section. In this paper, we give the physical design of the merger section for BXERL-FEL which merges three kinds of electron beam.
基金Supported by National Natural Science Foundation of China (10979005)National Basic Research Program of China(2009CB918600)
文摘With the development of the XFEL （X-ray free electron laser）, high quality diffraction patterns from nanocrystals have been achieved. The nanocrystals with different sizes and random orientations are injected to the XFEL beams and the diffraction patterns can be obtained by the so-called ＂diffraction-and-destruction＂ mode. The recovery of orientations is one of the most critical steps in reconstructing the 3D structure of nanocrystals. There is already an approach to solve the orientation problem by using the automated indexing software in crystallography. However, this method cannot distinguish the twin orientations in the cases of the symmetries of Bravais lattices higher than the point groups. Here we propose a new method to solve this problem. The shape transforms of nanocrystals can be determined from all of the intensities around the diffraction spots, and then Fourier transformation of a single crystal cell is obtained. The actual orientations of the patterns can be solved by comparing the values of the Fourier transformations of the crystal cell on the intersections of all patterns. This so-called ＂multiple-common-line＂ method can distinguish the twin orientations in the XFEL diffraction patterns successfully.
文摘In the proposal of the Beijing Advanced Light Source, a compact combination of XERL and XFEL using a common SC linac is being considered. In the meantime, an ERL-FEL test facility is being proposed and will be used for THz radiation. In this test facility, a L-band photocathode RF injector is needed. In this paper, we give the physical design of the L-band photocathode RF injector for the test facility.
