中国科学院高能物理研究所提出了ERL-FEL(Energy recovery linac-Free electron laser)"一机两用"的概念,通过同一直线加速器将能量回收加速器(Energy recovery linac,ERL)和自由电子激光(Free electron laser,FEL)结合到一...中国科学院高能物理研究所提出了ERL-FEL(Energy recovery linac-Free electron laser)"一机两用"的概念,通过同一直线加速器将能量回收加速器(Energy recovery linac,ERL)和自由电子激光(Free electron laser,FEL)结合到一起。本文讨论ERL-FEL两用实验装置主体屏蔽设计中,利用离散抽样的方法实现多个损失源项的整合,在同一FLUKA用户程序中实现多源抽样,并将蒙特卡罗计算结果与各源项独立处理的累积结果进行对比。计算表明,两者的结果吻合较好。基于束流损失源项整体建模的方法适用于其他小型直线加速器的整体屏蔽计算,可方便在其他装置上扩展应用。展开更多
RF superconducting cavities can work in CW mode or long pulse mode.RF superconducting technology is widely used in particle accelerators.The development of RF superconductivity is limited by the material,surface treat...RF superconducting cavities can work in CW mode or long pulse mode.RF superconducting technology is widely used in particle accelerators.The development of RF superconductivity is limited by the material,surface treatment and installation.SRF technology is improved greatly after dozens of years'researches.Lots of techniques and experiences have been accumulated by running superconducting accelerators.In recent years,researches and developments have been carried out for future large scientific project.New cavity shape and superconducting cavities made of large grain niobium are the hot frontiers in SRF field.Energy Recovery Linacs have been developed in recent years.ERLs has many advantages such as high efficiency,energy saving,good stability,low radiation level,etc.ERLs are more and more used in advanced light sources and free electron laser facilities.展开更多
BXERL is a proposal for a test facility （Beijing X-ray Energy Recovery Linac）, which requires its injector to provide an electron beam of 5 MeV, 77 pC/ bunch at a repetition rate of 130 MHz （average current of 10 m...BXERL is a proposal for a test facility （Beijing X-ray Energy Recovery Linac）, which requires its injector to provide an electron beam of 5 MeV, 77 pC/ bunch at a repetition rate of 130 MHz （average current of 10 mA）. In this paper, we present the design of the injector, which consists of a 500 kV photocathode DC gun equipped with a GaAs cathode preparation device, a 1.3 GHz normal conducting RF buncher, two solenoids, and one cryomodule containing two 1.3 GHz 2-cell superconducting RF cavities as the energy booster. The detailed beam dynamics show that the injector can generate electron bunches with a RMS normalized emittance of 1.49 πmm.mrad, a bunch length of 0.67 mm, a beam energy of 5 MeV and an energy spread of 0.72%.展开更多
The energy recovery linac test facility （ERL-TF）, which is a compact ERL-FEL （free electron laser） two-purpose machine, was proposed at the Institute of High Energy Physics, Beijing. As one important component of ...The energy recovery linac test facility （ERL-TF）, which is a compact ERL-FEL （free electron laser） two-purpose machine, was proposed at the Institute of High Energy Physics, Beijing. As one important component of the ERL-TF, the photo-injector that started with a photocathode direct-current gun has been designed. In this paper, optimization of the injector beam dynamics in low-charge operation mode is performed with iterative scans using Impact-T. In addition, the dependencies between the optimized beam quality and the initial offset at cathode and element parameters are, investigated. The tolerance of alignment and rotation errors is also analyzed.展开更多
A proposed compact ERL test facility at IHEP, Beijing, is presented in this paper, and includes the design parameters, the essential lattice, and the key components features, such as the photocathode DC gun and the CW...A proposed compact ERL test facility at IHEP, Beijing, is presented in this paper, and includes the design parameters, the essential lattice, and the key components features, such as the photocathode DC gun and the CW superconducting accelerating structures. Some important beam physics issues such as the space charge effect, the coherent synchrotron radiation （CSR） effect and the beam break-up （BBU） effect are briefly described with the simulation results.展开更多
Both the energy recovery linac （ERL） and the free electron laser （FEL） are considered to be candidate fourth generation light sources. It is proposed to combine an FEL into an ERL facility to integrate the advanta...Both the energy recovery linac （ERL） and the free electron laser （FEL） are considered to be candidate fourth generation light sources. It is proposed to combine an FEL into an ERL facility to integrate the advantages of both, and to realize a compact two-purpose light source. A test facility to verify this principle is being designed at the Institute of High Energy Physics, Beijing. One main concern is the beam breakup （BBU） instability which limits the available beam current. To this end, we developed a numerical simulation code to calculate the BBU threshold, which is found to have only a small reduction even in a high-FEL-bunch-charge operation mode, compared with that in the case with ERL bunches only. However, even with the ERL beam current far below the BBU threshold, we observed a fluctuation of the central orbit of the ERL bunches in the presence of an FEL beam. We then present a physical model of BBU and understand the mechanism of the orbit-fluctuation in an ERL-FEL two-purpose machine. We found that by choosing an appropriate FEL bunch repetition rate, the central orbit fluctuation amplitude can be well controlled.展开更多
The Beijing X-ray Energy Recovery Linac （BXERL） test facility is proposed in Institute of High Physics （IHEP）. In this proposal, the main linac requires the injector to provide an electron beam with 5 MeV energy a...The Beijing X-ray Energy Recovery Linac （BXERL） test facility is proposed in Institute of High Physics （IHEP）. In this proposal, the main linac requires the injector to provide an electron beam with 5 MeV energy and 10 mA average current. An injector based on DC gun technology is the first candidate electron source for BXERL. However, the field emission in the DC gun cavity makes it much more difficult to increase the high voltage to more than 500 kV. Another technology based on a 217 MHz normal conducting RF gun is proposed as the backup injector for this test facility. We have designed this RF gun with 2D SUPERFISH code and 3D MICROWAVE STUDIO code. In this paper, we present the optimized design of the gun cavity, the gun RF parameters and the set-up of the whole injector system. The detailed beam dynamics have been done and the simulation results show that the injector can generate electron bunches with RMS normalized emittance 1.0 7πmm-mrad, bunch length 0.77 mm, beam energy 5.0 MeV and energy spread 0.60%.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 energy recovery linac test facility （ERL-TF）, a compact ERL-FEL （free electron laser） two-purpose machine, has been proposed at the Institute of High Energy Physics, Beijing. As one important component of the ...The energy recovery linac test facility （ERL-TF）, a compact ERL-FEL （free electron laser） two-purpose machine, has been proposed at the Institute of High Energy Physics, Beijing. As one important component of the ERL-TF, the photo-injector was designed and preliminarily optimized. In this paper an evolutionary genetic method, non-dominated sorting genetic algorithm II, is applied to optimize the injector beam dynamics, especially in the high-charge operation mode. Study shows that using an incident laser with rms transverse size of 1-1.2 ram, the normalized emittance of the electron beam can be kept below 1 mm.mrad at the end of the injector. This work, together with the previous optimization of the low-charge operation mode by using the iterative scan method, provides guidance and confidence for future construction and commissioning of the ERL-TF injector.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
文摘中国科学院高能物理研究所提出了ERL-FEL(Energy recovery linac-Free electron laser)"一机两用"的概念,通过同一直线加速器将能量回收加速器(Energy recovery linac,ERL)和自由电子激光(Free electron laser,FEL)结合到一起。本文讨论ERL-FEL两用实验装置主体屏蔽设计中,利用离散抽样的方法实现多个损失源项的整合,在同一FLUKA用户程序中实现多源抽样,并将蒙特卡罗计算结果与各源项独立处理的累积结果进行对比。计算表明,两者的结果吻合较好。基于束流损失源项整体建模的方法适用于其他小型直线加速器的整体屏蔽计算,可方便在其他装置上扩展应用。
文摘RF superconducting cavities can work in CW mode or long pulse mode.RF superconducting technology is widely used in particle accelerators.The development of RF superconductivity is limited by the material,surface treatment and installation.SRF technology is improved greatly after dozens of years'researches.Lots of techniques and experiences have been accumulated by running superconducting accelerators.In recent years,researches and developments have been carried out for future large scientific project.New cavity shape and superconducting cavities made of large grain niobium are the hot frontiers in SRF field.Energy Recovery Linacs have been developed in recent years.ERLs has many advantages such as high efficiency,energy saving,good stability,low radiation level,etc.ERLs are more and more used in advanced light sources and free electron laser facilities.
基金Supported by Creative Research Foundation of Institute of High Energy Physics (H85453G0U2)Key Project of Chinese National Programs for Fundamental Research and Development (2008CB817700)
文摘BXERL is a proposal for a test facility （Beijing X-ray Energy Recovery Linac）, which requires its injector to provide an electron beam of 5 MeV, 77 pC/ bunch at a repetition rate of 130 MHz （average current of 10 mA）. In this paper, we present the design of the injector, which consists of a 500 kV photocathode DC gun equipped with a GaAs cathode preparation device, a 1.3 GHz normal conducting RF buncher, two solenoids, and one cryomodule containing two 1.3 GHz 2-cell superconducting RF cavities as the energy booster. The detailed beam dynamics show that the injector can generate electron bunches with a RMS normalized emittance of 1.49 πmm.mrad, a bunch length of 0.67 mm, a beam energy of 5 MeV and an energy spread of 0.72%.
文摘The energy recovery linac test facility （ERL-TF）, which is a compact ERL-FEL （free electron laser） two-purpose machine, was proposed at the Institute of High Energy Physics, Beijing. As one important component of the ERL-TF, the photo-injector that started with a photocathode direct-current gun has been designed. In this paper, optimization of the injector beam dynamics in low-charge operation mode is performed with iterative scans using Impact-T. In addition, the dependencies between the optimized beam quality and the initial offset at cathode and element parameters are, investigated. The tolerance of alignment and rotation errors is also analyzed.
文摘A proposed compact ERL test facility at IHEP, Beijing, is presented in this paper, and includes the design parameters, the essential lattice, and the key components features, such as the photocathode DC gun and the CW superconducting accelerating structures. Some important beam physics issues such as the space charge effect, the coherent synchrotron radiation （CSR） effect and the beam break-up （BBU） effect are briefly described with the simulation results.
文摘Both the energy recovery linac （ERL） and the free electron laser （FEL） are considered to be candidate fourth generation light sources. It is proposed to combine an FEL into an ERL facility to integrate the advantages of both, and to realize a compact two-purpose light source. A test facility to verify this principle is being designed at the Institute of High Energy Physics, Beijing. One main concern is the beam breakup （BBU） instability which limits the available beam current. To this end, we developed a numerical simulation code to calculate the BBU threshold, which is found to have only a small reduction even in a high-FEL-bunch-charge operation mode, compared with that in the case with ERL bunches only. However, even with the ERL beam current far below the BBU threshold, we observed a fluctuation of the central orbit of the ERL bunches in the presence of an FEL beam. We then present a physical model of BBU and understand the mechanism of the orbit-fluctuation in an ERL-FEL two-purpose machine. We found that by choosing an appropriate FEL bunch repetition rate, the central orbit fluctuation amplitude can be well controlled.
基金Supported by Creative Research Foundation of Institute of High Energy Physics (H85453G0U2)Key Project of Chinese National Programs for Fundamental Research and Development (2008CB817700)
文摘The Beijing X-ray Energy Recovery Linac （BXERL） test facility is proposed in Institute of High Physics （IHEP）. In this proposal, the main linac requires the injector to provide an electron beam with 5 MeV energy and 10 mA average current. An injector based on DC gun technology is the first candidate electron source for BXERL. However, the field emission in the DC gun cavity makes it much more difficult to increase the high voltage to more than 500 kV. Another technology based on a 217 MHz normal conducting RF gun is proposed as the backup injector for this test facility. We have designed this RF gun with 2D SUPERFISH code and 3D MICROWAVE STUDIO code. In this paper, we present the optimized design of the gun cavity, the gun RF parameters and the set-up of the whole injector system. The detailed beam dynamics have been done and the simulation results show that the injector can generate electron bunches with RMS normalized emittance 1.0 7πmm-mrad, bunch length 0.77 mm, beam energy 5.0 MeV and energy spread 0.60%.
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.
文摘The energy recovery linac test facility （ERL-TF）, a compact ERL-FEL （free electron laser） two-purpose machine, has been proposed at the Institute of High Energy Physics, Beijing. As one important component of the ERL-TF, the photo-injector was designed and preliminarily optimized. In this paper an evolutionary genetic method, non-dominated sorting genetic algorithm II, is applied to optimize the injector beam dynamics, especially in the high-charge operation mode. Study shows that using an incident laser with rms transverse size of 1-1.2 ram, the normalized emittance of the electron beam can be kept below 1 mm.mrad at the end of the injector. This work, together with the previous optimization of the low-charge operation mode by using the iterative scan method, provides guidance and confidence for future construction and commissioning of the ERL-TF injector.
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.
