The proton beam with energy around 100 MeV has seen wide applications in modern scientific research and in various fields.However,proton sources in China fall short for meeting experimental needs owing to the vast siz...The proton beam with energy around 100 MeV has seen wide applications in modern scientific research and in various fields.However,proton sources in China fall short for meeting experimental needs owing to the vast size and expensive traditional proton accelerators.The Institute of Nuclear Science and Technology of Sichuan University proposed to build a 3 GHz side-coupled cavity linac(SCL)for re-accelerating a 26 MeV proton beam extracted from a CS-30 cyclotron to 120 MeV.We carried out investigations into several vital factors of S-band SCL for proton acceleration,such as optimization of SCL cavity geometry,end cell tuning,and bridge coupler design.Results demonstrated that the effective shunt impedance per unit length ranged from 22.5 to 59.8 MX/m throughout the acceleration process,and the acceleration gradient changed from 11.5 to 15.7 MV/m when the maximum surface electric field was equivalent to Kilpatrick electric field.We obtained equivalent circuit parameters of the biperiodic structures and applied them to the end cell tuning;results of the theoretical analysis agreed well with the 3D simulation.We designed and optimized a bridge coupler based on the previously obtained biperiodic structure parameters,and the field distribution un-uniformness was\1.5%for a two-tank module.The radio frequency power distribution system of the linac was obtained based on the preliminary beam dynamics design.展开更多
Based on the present coupled mode theory of the photonic crystal resonator array in this paper, we propose a novel side-coupled waveguide to achieve highly efficient coupling of photonic crystal devices. It is found t...Based on the present coupled mode theory of the photonic crystal resonator array in this paper, we propose a novel side-coupled waveguide to achieve highly efficient coupling of photonic crystal devices. It is found that the coupling efficiency is sensitive to the interval, the total number and the quality factor of the resonator. Considering the coupling efficiency and the coupling region, we select five resonators with an interval of six lattice periods. By optimizing the structure parameters of the waveguide and resonator, the quality factors of the resonator can be modulated and the coupling efficiency of the side-coupled waveguide reaches 95.47% in theory. Compared with other coupling methods, the side-coupled waveguide can realize efficient coupling with a compact structure, a high level of integration and a low degree of operational difficulties.展开更多
The 10-MeV Accelerator-Driven Subcritical(ADS)system Injector-I test stand at the Institute of High Energy Physics(IHEP)is a testing facility dedicated to demonstrating the feasibility of the spoke-based super-conduct...The 10-MeV Accelerator-Driven Subcritical(ADS)system Injector-I test stand at the Institute of High Energy Physics(IHEP)is a testing facility dedicated to demonstrating the feasibility of the spoke-based super-conducting(SC)linear accelerator(linac)for the ADS project in China.The injector adopted a four-vane copper structure radio frequency quadrupole(RFQ)with an output energy of 3.2 MeV and an SC section accommodating 14 β_(g)=0.12 single spoke cavities,14 SC solenoids,and 14 cold beam position monitors(BPMs).A 10-MeV pulsed beam with a beam current of 10 mA and a 2-mA continuous wave(CW)beam were successfully shooting through.The commissioning results confirmed the feasibility of using a 325-MHz spoke-type cavity for accelerating the proton beam in the low β and medium β sections.This paper describes the results achieved,the difficulties encountered,and the experiences obtained during commissioning.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
In order to update the beam power from 100 kW to 500 kW in the China Spallation neutron source （CSNS） Phase II, one of the important measures is to replace the 80 m long beam transport line between the present 80 Me...In order to update the beam power from 100 kW to 500 kW in the China Spallation neutron source （CSNS） Phase II, one of the important measures is to replace the 80 m long beam transport line between the present 80 MeV linac injector and the rapid cycling synchrotron （RCS） to another kind of acceleration structure. In this paper, we proposed a scheme based on 324 MHz double-spoke superconducting cavities. Unlike the superconducting elliptical cavity and normal conducting coupled cavity linac （CCL） structure, the double-spoke cavity belongs to the TE mode structure and has a smaller transverse dimension compared with that of the TH mode one. It can work at base frequency as the drift tube Linac （DTL） section, so that the cost and complexity of the RF system will be much decreased, and the behaviors of the beam dynamics are also improved significantly because of the low charge density and larger longitudinal acceptance. Furthermore, because of the relatively longer interactive length between the charged particle and the electromagnetic field per cell, it needs relatively less cell numbers and it has larger velocity acceptance compared with the double frequency TH structures. The superconducting section consists of 14 periods, each of which includes 3 superconducting cavities encapsulated in one cryomodule and a doublet in room temperate. The general considerations on cavity and beam dynamics design are discussed and the main results are presented.展开更多
Continuous wave （CW） high current proton linacs have wide applications as the front end of high power proton machines. The low energy part of such a linac is the most difficult and there is currently no widely accep...Continuous wave （CW） high current proton linacs have wide applications as the front end of high power proton machines. The low energy part of such a linac is the most difficult and there is currently no widely accepted solution. Based on the analysis of the focusing properties of the CW low energy proton linac, a 10 MeV low energy normal conducting proton linac based on equidistant seven-gap Cross-bar H-type （CH） cavities is proposed. The linac is composed of ten 7-gap CH cavities and the transverse focusing is maintained by quadrupole doublets located between the cavities. The total length of the linac is less than 6 meters and the average acceleration gradient is about 1.2 MeV/m. The electromagnetic properties of the cavities are investigated by Microwave Studio. At the nominal acceleration gradient the maximum surface electric field in the cavities is less than 1.3 times the Kilpatrick limit, and the Ohmic loss of each cavity is less than 35 kW. Multi-particle beam dynamics simulations are performed with Tracewin code, and the results show that the beam dynamics of the linac are quite stable, the linac has the capability to accelerate up to 30 mA beam with acceptable dynamics behavior.展开更多
将滑模极值搜索算法引入基于腔体反射信号的SSC-LINAC射频四极场加速器(Radio Frequency Quadrupole, RFQ)腔体频率稳定系统设计中,结合Lyapunov稳定性理论和SSC-LINAC RFQ高频系统的特点,对滑模极值搜索算法的控制增益和参考信号进行改...将滑模极值搜索算法引入基于腔体反射信号的SSC-LINAC射频四极场加速器(Radio Frequency Quadrupole, RFQ)腔体频率稳定系统设计中,结合Lyapunov稳定性理论和SSC-LINAC RFQ高频系统的特点,对滑模极值搜索算法的控制增益和参考信号进行改进;通过求解微分方程,得到腔体反射信号关于时间和调谐杆位置的函数。通过软件仿真和设计硬件系统,对基于滑模极值搜索算法的调谐过程进行仿真与实际测试,结果显示,所设计的频率稳定系统能够在较短时间内实现SSC-LINAC RFQ腔体功率自动馈入过程且频率稳定度满足设计指标要求,通过了长时间稳定性试验。证明了将滑模极值搜索算法应用于高频谐振腔调谐工作的可行性。展开更多
The China ADS（C-ADS） project proposes to build a 1000 MW Accelerator Driven sub-critical System around 2032. The accelerator will work in CW mode with 10 mA in beam current and 1.5 GeV in final beam energy. The lina...The China ADS（C-ADS） project proposes to build a 1000 MW Accelerator Driven sub-critical System around 2032. The accelerator will work in CW mode with 10 mA in beam current and 1.5 GeV in final beam energy. The linac is composed of two major sections： the injector section and the main linac section. There are two diferent schemes for the injector section. The Injector-scheme is based on a 325 MHz RFQ and superconducting spoke cavities of the same RF frequency and the Injector-scheme is based on a 162.5 MHz RFQ and superconducting HWR cavities of the same frequency. The main linac design will be diferent for diferent injector choices. The two diferent designs for the main linac have been studied according to the beam characteristics from the diferent injector schemes.展开更多
基金supported by the National Natural Science Foundation of China(Nos.11375122 and 11875197)
文摘The proton beam with energy around 100 MeV has seen wide applications in modern scientific research and in various fields.However,proton sources in China fall short for meeting experimental needs owing to the vast size and expensive traditional proton accelerators.The Institute of Nuclear Science and Technology of Sichuan University proposed to build a 3 GHz side-coupled cavity linac(SCL)for re-accelerating a 26 MeV proton beam extracted from a CS-30 cyclotron to 120 MeV.We carried out investigations into several vital factors of S-band SCL for proton acceleration,such as optimization of SCL cavity geometry,end cell tuning,and bridge coupler design.Results demonstrated that the effective shunt impedance per unit length ranged from 22.5 to 59.8 MX/m throughout the acceleration process,and the acceleration gradient changed from 11.5 to 15.7 MV/m when the maximum surface electric field was equivalent to Kilpatrick electric field.We obtained equivalent circuit parameters of the biperiodic structures and applied them to the end cell tuning;results of the theoretical analysis agreed well with the 3D simulation.We designed and optimized a bridge coupler based on the previously obtained biperiodic structure parameters,and the field distribution un-uniformness was\1.5%for a two-tank module.The radio frequency power distribution system of the linac was obtained based on the preliminary beam dynamics design.
基金Project supported by the National Natural Science Foundation of China (Grant No. 60877031)
文摘Based on the present coupled mode theory of the photonic crystal resonator array in this paper, we propose a novel side-coupled waveguide to achieve highly efficient coupling of photonic crystal devices. It is found that the coupling efficiency is sensitive to the interval, the total number and the quality factor of the resonator. Considering the coupling efficiency and the coupling region, we select five resonators with an interval of six lattice periods. By optimizing the structure parameters of the waveguide and resonator, the quality factors of the resonator can be modulated and the coupling efficiency of the side-coupled waveguide reaches 95.47% in theory. Compared with other coupling methods, the side-coupled waveguide can realize efficient coupling with a compact structure, a high level of integration and a low degree of operational difficulties.
基金This work was supported by Strategic Priority Research Program of the Chinese Academy of Sciences(No.XDA03030201)the Key Laboratory of Particle Acceleration Physics and Technology Autonomous Foundation of CAS China(No.JSQ2017ZZ01).
文摘The 10-MeV Accelerator-Driven Subcritical(ADS)system Injector-I test stand at the Institute of High Energy Physics(IHEP)is a testing facility dedicated to demonstrating the feasibility of the spoke-based super-conducting(SC)linear accelerator(linac)for the ADS project in China.The injector adopted a four-vane copper structure radio frequency quadrupole(RFQ)with an output energy of 3.2 MeV and an SC section accommodating 14 β_(g)=0.12 single spoke cavities,14 SC solenoids,and 14 cold beam position monitors(BPMs).A 10-MeV pulsed beam with a beam current of 10 mA and a 2-mA continuous wave(CW)beam were successfully shooting through.The commissioning results confirmed the feasibility of using a 325-MHz spoke-type cavity for accelerating the proton beam in the low β and medium β sections.This paper describes the results achieved,the difficulties encountered,and the experiences obtained during commissioning.
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 National Nature Sciences Foundation of China(11375122,91126003)China ADS Project
文摘In order to update the beam power from 100 kW to 500 kW in the China Spallation neutron source （CSNS） Phase II, one of the important measures is to replace the 80 m long beam transport line between the present 80 MeV linac injector and the rapid cycling synchrotron （RCS） to another kind of acceleration structure. In this paper, we proposed a scheme based on 324 MHz double-spoke superconducting cavities. Unlike the superconducting elliptical cavity and normal conducting coupled cavity linac （CCL） structure, the double-spoke cavity belongs to the TE mode structure and has a smaller transverse dimension compared with that of the TH mode one. It can work at base frequency as the drift tube Linac （DTL） section, so that the cost and complexity of the RF system will be much decreased, and the behaviors of the beam dynamics are also improved significantly because of the low charge density and larger longitudinal acceptance. Furthermore, because of the relatively longer interactive length between the charged particle and the electromagnetic field per cell, it needs relatively less cell numbers and it has larger velocity acceptance compared with the double frequency TH structures. The superconducting section consists of 14 periods, each of which includes 3 superconducting cavities encapsulated in one cryomodule and a doublet in room temperate. The general considerations on cavity and beam dynamics design are discussed and the main results are presented.
基金Supported by National Natural Science Foundation of China(11375122,91126003)
文摘Continuous wave （CW） high current proton linacs have wide applications as the front end of high power proton machines. The low energy part of such a linac is the most difficult and there is currently no widely accepted solution. Based on the analysis of the focusing properties of the CW low energy proton linac, a 10 MeV low energy normal conducting proton linac based on equidistant seven-gap Cross-bar H-type （CH） cavities is proposed. The linac is composed of ten 7-gap CH cavities and the transverse focusing is maintained by quadrupole doublets located between the cavities. The total length of the linac is less than 6 meters and the average acceleration gradient is about 1.2 MeV/m. The electromagnetic properties of the cavities are investigated by Microwave Studio. At the nominal acceleration gradient the maximum surface electric field in the cavities is less than 1.3 times the Kilpatrick limit, and the Ohmic loss of each cavity is less than 35 kW. Multi-particle beam dynamics simulations are performed with Tracewin code, and the results show that the beam dynamics of the linac are quite stable, the linac has the capability to accelerate up to 30 mA beam with acceptable dynamics behavior.
文摘The China ADS（C-ADS） project proposes to build a 1000 MW Accelerator Driven sub-critical System around 2032. The accelerator will work in CW mode with 10 mA in beam current and 1.5 GeV in final beam energy. The linac is composed of two major sections： the injector section and the main linac section. There are two diferent schemes for the injector section. The Injector-scheme is based on a 325 MHz RFQ and superconducting spoke cavities of the same RF frequency and the Injector-scheme is based on a 162.5 MHz RFQ and superconducting HWR cavities of the same frequency. The main linac design will be diferent for diferent injector choices. The two diferent designs for the main linac have been studied according to the beam characteristics from the diferent injector schemes.
