为了提高滤波器的带外抑制度和选择性,首次提出了一种双阶拓扑结构的带通滤波器。采用奇偶模方法对工字型双模谐振器的特性进行了分析,通带内具有四个谐振模式。滤波器有效尺寸为13.7 mm×5.35 mm,等于0.56λ_g×0.22λ_g(λ_g...为了提高滤波器的带外抑制度和选择性,首次提出了一种双阶拓扑结构的带通滤波器。采用奇偶模方法对工字型双模谐振器的特性进行了分析,通带内具有四个谐振模式。滤波器有效尺寸为13.7 mm×5.35 mm,等于0.56λ_g×0.22λ_g(λ_g为中心频率处的波导波长)。该滤波器的中心频率为7.34 GHz,相对带宽为20.9%,通带内最小插损为1.9 d B,阻带的三个传输零点分别位于3.17,8.36和9.61 GHz,上下阻带抑制度分别大于30 d B和46 d B,一次杂散抑制度大于18 d B。该滤波器具有结构紧凑,带外抑制度与选择性较高的优点。展开更多
首次提出一种基于SIR(Stepped Impendence Resonator)的准椭圆函数微带带通滤波器。两阶SIR与I/O馈线之间采用边缘耦合的方式,在上下阻带各产生一个传输零点,在几乎不增加滤波器尺寸的情况下,有效提高了滤波器的带外抑制度与选择性,并...首次提出一种基于SIR(Stepped Impendence Resonator)的准椭圆函数微带带通滤波器。两阶SIR与I/O馈线之间采用边缘耦合的方式,在上下阻带各产生一个传输零点,在几乎不增加滤波器尺寸的情况下,有效提高了滤波器的带外抑制度与选择性,并且有效抑制了阻带的一次杂散。滤波器的有效尺寸为16 mm×3.32 mm,等于0.45λ_g×0.093λ_g(λ_g为通带中心频率的波导波长),中心频率位于4.95 GHz,带内最小插损为1.6 d B,两个传输零点分别位于2.34 GHz,6.3 GHz,下阻带边缘抑制度大于40 d B,上阻带边缘抑制度大于35 d B,阻带一阶杂散抑制度大于25 d B,大于20 d B上阻带宽度为9 GHz。展开更多
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
In this paper, we present the design and optimization of a side-coupled accelerating structure with an energy switch. The beam parameters are optimized, and the electric field asymmetry in the first cell is analyzed. ...In this paper, we present the design and optimization of a side-coupled accelerating structure with an energy switch. The beam parameters are optimized, and the electric field asymmetry in the first cell is analyzed. The new structure we designed has an improvement of 10 times in the accelerating field symmetry. Thermo-mechanical analysis is performed based on the electromagnetic results. The highest temperature is 72.5 ℃ at the nose cone, and the maximal deformation is 73 μm at the outer edge of the coupling cavity.展开更多
Based on Fabry model and finite-different time-domain(FDTD) method, the plasmonic structure composed of a metal-insulator-metal(MIM) bus waveguide and a side-coupled resonator was investigated. It is found that the tr...Based on Fabry model and finite-different time-domain(FDTD) method, the plasmonic structure composed of a metal-insulator-metal(MIM) bus waveguide and a side-coupled resonator was investigated. It is found that the transmission features can be regulated by the cavity width and coupling distance. Electromagnetically induced transparency(EIT)-like transmission can be excited by adding an identical resonator on the pre-existing structure. Combining the foregoing theoretical analysis with coupled mode theory(CMT), the formation process of the EIT-like transmission was detailedly analyzed. EIT-like transmission can also be excited in plasmonic structure with two detuned resonators. By altering the structure parameters, the transparency window can be purposefully modulated. With the merits of compact structure and simplicity in fabrication, the proposed structures may have a broad prospect of applications in highly integrated optical circuits.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
We present a theoretical study of mode evolution in high-power distributed side-coupled cladding-pumped(DSCCP)fiber amplifiers.A semi-analytical model taking the side-pumping schemes,transverse mode competition,and st...We present a theoretical study of mode evolution in high-power distributed side-coupled cladding-pumped(DSCCP)fiber amplifiers.A semi-analytical model taking the side-pumping schemes,transverse mode competition,and stimulated thermal Rayleigh scattering into consideration has been built,which can model the static and dynamic mode evolution in high-power DSCCP fiber amplifiers.The mode evolution behavior has been investigated with variation of the fiber amplifier parameters,such as the pump power distribution,the length of the DSCCP fiber,the averaged coupling coefficient,the number of the pump cores and the arrangement of the pump cores.Interestingly,it revealed that static mode evolution induced by transverse mode competition is different from the dynamic evolution induced by stimulated thermal Rayleigh scattering.This shows that the high-order mode experiences a slightly higher gain in DSCCP fiber amplifiers,but the mode instability thresholds for DSCCP fiber amplifiers are higher than those for their end-coupled counterparts.By increasing the pump core number and reducing the averaged coupling coefficient,the mode instability threshold can be increased,which indicates that DSCCP fibers can provide additional mitigation strategies of dynamic mode instability.展开更多
利用CST studio suite程序对边耦合直线加速结构的加速腔及耦合腔进行建模仿真,并进行优化。加速腔结构由11个参数决定,优化过程需平衡多个参数,包括本征模式、高频特性、最大表面电场、有效分路阻抗及渡越时间因子;耦合腔的优化基于维...利用CST studio suite程序对边耦合直线加速结构的加速腔及耦合腔进行建模仿真,并进行优化。加速腔结构由11个参数决定,优化过程需平衡多个参数,包括本征模式、高频特性、最大表面电场、有效分路阻抗及渡越时间因子;耦合腔的优化基于维持本征模式3 GHz。结果表明,在26~120 MeV整个加速过程中,加速腔的有效分路阻抗为22.5~59.8 MΩ·m^(-1),加速梯度为11~14.7 MV·m^(-1)。展开更多
文摘为了提高滤波器的带外抑制度和选择性,首次提出了一种双阶拓扑结构的带通滤波器。采用奇偶模方法对工字型双模谐振器的特性进行了分析,通带内具有四个谐振模式。滤波器有效尺寸为13.7 mm×5.35 mm,等于0.56λ_g×0.22λ_g(λ_g为中心频率处的波导波长)。该滤波器的中心频率为7.34 GHz,相对带宽为20.9%,通带内最小插损为1.9 d B,阻带的三个传输零点分别位于3.17,8.36和9.61 GHz,上下阻带抑制度分别大于30 d B和46 d B,一次杂散抑制度大于18 d B。该滤波器具有结构紧凑,带外抑制度与选择性较高的优点。
文摘首次提出一种基于SIR(Stepped Impendence Resonator)的准椭圆函数微带带通滤波器。两阶SIR与I/O馈线之间采用边缘耦合的方式,在上下阻带各产生一个传输零点,在几乎不增加滤波器尺寸的情况下,有效提高了滤波器的带外抑制度与选择性,并且有效抑制了阻带的一次杂散。滤波器的有效尺寸为16 mm×3.32 mm,等于0.45λ_g×0.093λ_g(λ_g为通带中心频率的波导波长),中心频率位于4.95 GHz,带内最小插损为1.6 d B,两个传输零点分别位于2.34 GHz,6.3 GHz,下阻带边缘抑制度大于40 d B,上阻带边缘抑制度大于35 d B,阻带一阶杂散抑制度大于25 d B,大于20 d B上阻带宽度为9 GHz。
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.
文摘In this paper, we present the design and optimization of a side-coupled accelerating structure with an energy switch. The beam parameters are optimized, and the electric field asymmetry in the first cell is analyzed. The new structure we designed has an improvement of 10 times in the accelerating field symmetry. Thermo-mechanical analysis is performed based on the electromagnetic results. The highest temperature is 72.5 ℃ at the nose cone, and the maximal deformation is 73 μm at the outer edge of the coupling cavity.
基金Project(61275174)supported by the National Natural Science Foundations of ChinaProject(20100162110068)supported by the Doctoral Program of Higher Education of China
文摘Based on Fabry model and finite-different time-domain(FDTD) method, the plasmonic structure composed of a metal-insulator-metal(MIM) bus waveguide and a side-coupled resonator was investigated. It is found that the transmission features can be regulated by the cavity width and coupling distance. Electromagnetically induced transparency(EIT)-like transmission can be excited by adding an identical resonator on the pre-existing structure. Combining the foregoing theoretical analysis with coupled mode theory(CMT), the formation process of the EIT-like transmission was detailedly analyzed. EIT-like transmission can also be excited in plasmonic structure with two detuned resonators. By altering the structure parameters, the transparency window can be purposefully modulated. With the merits of compact structure and simplicity in fabrication, the proposed structures may have a broad prospect of applications in highly integrated optical circuits.
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.
基金funded by the National Natural Science Foundation of China(NSFC)(61905226)the Youth Talent Climbing Foundation of the Research Center of Laser Fusion。
文摘We present a theoretical study of mode evolution in high-power distributed side-coupled cladding-pumped(DSCCP)fiber amplifiers.A semi-analytical model taking the side-pumping schemes,transverse mode competition,and stimulated thermal Rayleigh scattering into consideration has been built,which can model the static and dynamic mode evolution in high-power DSCCP fiber amplifiers.The mode evolution behavior has been investigated with variation of the fiber amplifier parameters,such as the pump power distribution,the length of the DSCCP fiber,the averaged coupling coefficient,the number of the pump cores and the arrangement of the pump cores.Interestingly,it revealed that static mode evolution induced by transverse mode competition is different from the dynamic evolution induced by stimulated thermal Rayleigh scattering.This shows that the high-order mode experiences a slightly higher gain in DSCCP fiber amplifiers,but the mode instability thresholds for DSCCP fiber amplifiers are higher than those for their end-coupled counterparts.By increasing the pump core number and reducing the averaged coupling coefficient,the mode instability threshold can be increased,which indicates that DSCCP fibers can provide additional mitigation strategies of dynamic mode instability.
基金Supported by the National Natural Science Foundation of China(11475201)the Youth Innovation Promotion Association of Chinese Academy of Sciences,China
