Complex function and general conformal mapping methods are used to investigate the scattering of elastic shear waves by an elliptical cylindrical cavity in a radially inhomogeneous medium. The conformal mappings are i...Complex function and general conformal mapping methods are used to investigate the scattering of elastic shear waves by an elliptical cylindrical cavity in a radially inhomogeneous medium. The conformal mappings are introduced to solve scattering by an arbitrary cavity for the Helmholtz equation with variable coefficient through the transformed standard Helmholtz equation with a circular cavity. The medium density depends on the distance from the origin with a power-law variation and the shear elastic modulus is constant. The complex-value displacements and stresses of the in.homogeneous medium are explicitly obtained and the distributions of the dynamic stress for the case of an elliptical cavity are discussed. The accuracy of the present approach is verified by comparing the present solution results with the available published data. Numerical results demonstrate that the wave number, inhomogeneous parameters and different values of aspect ratio have significant influence on the dynamic stress concentration factors around the elliptical cavity.展开更多
Background A lowβsuperconducting elliptical cavity was designed for the China Spallation Neutron Source phase II project(CSNS-II).Methods The method to improve the mechanical stability of the lowβsuperconducting ell...Background A lowβsuperconducting elliptical cavity was designed for the China Spallation Neutron Source phase II project(CSNS-II).Methods The method to improve the mechanical stability of the lowβsuperconducting elliptical cavity was introduced,and the corresponding mechanical design was given.The software COMSOL Multiphysics and ANSYS APDL were used to calculate the static Lorentz force detuning factor k_(L)(LFD)and the helium pressure sensitivity factor k_(p)(DFDP)of the bare cavity,which were−4.71 Hz(MV/m)^(−2) and−21.1 Hz/mbar,respectively.The double-ring stiffeners reinforcement scheme was adopted.Results The radii of the double-ring stiffeners were 70 and 135 mm,respectively.The structure design of the helium vessel of the cavity was given.The following is the mechanical parameters of the reinforced cavity,the tuning sensitivity is 199.8 kHz/mm,longitudinal stiffness is 4.76kN/mm,k_(L) and k_(p) were−1.39 Hz(MV/m)^(−2) and 4.67 Hz/mbar,respectively,which met the operating requirements.The tuning sensitivity and stiffness of the reinforced cavity with different wall thicknesses were optimized,and the final wall thickness was selected as 4 mm.Conclusion The mechanical design of CSNS-II 648 MHz five-cell lowβsuperconducting elliptical cavity was introduced systematically in the paper.The LFD,DFDP,and the maximum surface stress of the cavity were reduced by optimizing the cavity wall thickness and the position of the double-ring stiffeners.The reinforced cavity met operational requirements.展开更多
The polarization of traditional photonic crystal(PC) vertical cavity surface emitting laser(VCSEL) is uncontrollable,resulting in the bit error increasing easily.Elliptical hole photonic crystal can control the tr...The polarization of traditional photonic crystal(PC) vertical cavity surface emitting laser(VCSEL) is uncontrollable,resulting in the bit error increasing easily.Elliptical hole photonic crystal can control the transverse mode and polarization of VCSEL efficiently.We analyze the far field divergence angle,and birefringence of elliptical hole PC VCSEL.When the ratio of minor axis to major axis b/a = 0.7,the PC VCSEL can obtain single mode and polarization.According to the simulation results,we fabricate the device successfully.The output power is 1.7 mW,the far field divergence angle is less than 10°,and the side mode suppression ratio is over 30 dB.The output power in the Y direction is 20 times that in the X direction.展开更多
In this paper,the dynamic stress concentration and scattering of SH-waves by bi-material structures that possess an interface elliptic cavity are investigated.First,by using the complex function method,the Green's...In this paper,the dynamic stress concentration and scattering of SH-waves by bi-material structures that possess an interface elliptic cavity are investigated.First,by using the complex function method,the Green's function is constructed.This yields the solution of the displacement field for an elastic half space with a semi-elliptic canyon impacted by an anti-plane harmonic line source loading on the horizontal surface.Then,the problem is divided into an upper and lower half space along the horizontal interface,regarded as a harmony model.In order to satisfy the integral continuity condition, the unknown anti-plane forces are applied to the interface.The integral equations with unknown forces can be established through the continuity condition,and after transformation,the algebraic equations are solved numerically.Finally,the distribution of the dynamic stress concentration factor(DSCF)around the elliptic cavity is given and the effect of different parameters on DSCF is discussed.展开更多
This paper computes the conductance of an open ellipse cavity and discusses the effect of finite leads on conductance. The lead introduces mode coupling with bound states in the cavity which contributes to Fano resona...This paper computes the conductance of an open ellipse cavity and discusses the effect of finite leads on conductance. The lead introduces mode coupling with bound states in the cavity which contributes to Fano resonant line shapes in conductance. By examining the resonant states in the cavity, the effects of state mixing and annular probability distribution of wave function due to the presence of leads are found. The results have been compared with the transport properties of other systems. The finite leads result in two effects, i.e. the evanescent mode contribution and additional oscillations, to the conductance.展开更多
5-cell elliptical cavities have been selected for the main linac of the China Accelerator Driven subcritical System (C-ADS) in the medium energy section. According to the design, each cavity should be driven with ra...5-cell elliptical cavities have been selected for the main linac of the China Accelerator Driven subcritical System (C-ADS) in the medium energy section. According to the design, each cavity should be driven with radio frequency (RF) energy up to 150 kW by a fundamental power coupler (FPC). As the cavities work with high quality factor and high accelerating gradient, the coupler should keep the cavity from contamination in the assembly procedure. To fulfil the requirements, a single-window coaxial type coupler was designed with the capabilities of handling high RF power, class 10 clean room assembly, and heat load control. This paper presents the coupler design and gives details of RF design, heat load optimization and thermal analysis as well as multipacting simulations. In addition, a primary high power test has been performed and is described in this paper.展开更多
基金National Science&Technology Pillar Program under Grant No.2015BAK17B06Natural Science Foundation of Heilongjiang Province,China under Grant No.A201310+1 种基金Scientific Research Starting Foundation for Post Doctorate of Heilongjiang Province,China under Grant No.LBH-Q13040the Fundamental Research Funds for the Central Universities of China under Grant No.HEUCF150203
文摘Complex function and general conformal mapping methods are used to investigate the scattering of elastic shear waves by an elliptical cylindrical cavity in a radially inhomogeneous medium. The conformal mappings are introduced to solve scattering by an arbitrary cavity for the Helmholtz equation with variable coefficient through the transformed standard Helmholtz equation with a circular cavity. The medium density depends on the distance from the origin with a power-law variation and the shear elastic modulus is constant. The complex-value displacements and stresses of the in.homogeneous medium are explicitly obtained and the distributions of the dynamic stress for the case of an elliptical cavity are discussed. The accuracy of the present approach is verified by comparing the present solution results with the available published data. Numerical results demonstrate that the wave number, inhomogeneous parameters and different values of aspect ratio have significant influence on the dynamic stress concentration factors around the elliptical cavity.
基金Work supported by Project of Basic and Applied Basic Research Fund of Guangdong Province:Yue Guan joint fund(2019B1515120012).
文摘Background A lowβsuperconducting elliptical cavity was designed for the China Spallation Neutron Source phase II project(CSNS-II).Methods The method to improve the mechanical stability of the lowβsuperconducting elliptical cavity was introduced,and the corresponding mechanical design was given.The software COMSOL Multiphysics and ANSYS APDL were used to calculate the static Lorentz force detuning factor k_(L)(LFD)and the helium pressure sensitivity factor k_(p)(DFDP)of the bare cavity,which were−4.71 Hz(MV/m)^(−2) and−21.1 Hz/mbar,respectively.The double-ring stiffeners reinforcement scheme was adopted.Results The radii of the double-ring stiffeners were 70 and 135 mm,respectively.The structure design of the helium vessel of the cavity was given.The following is the mechanical parameters of the reinforced cavity,the tuning sensitivity is 199.8 kHz/mm,longitudinal stiffness is 4.76kN/mm,k_(L) and k_(p) were−1.39 Hz(MV/m)^(−2) and 4.67 Hz/mbar,respectively,which met the operating requirements.The tuning sensitivity and stiffness of the reinforced cavity with different wall thicknesses were optimized,and the final wall thickness was selected as 4 mm.Conclusion The mechanical design of CSNS-II 648 MHz five-cell lowβsuperconducting elliptical cavity was introduced systematically in the paper.The LFD,DFDP,and the maximum surface stress of the cavity were reduced by optimizing the cavity wall thickness and the position of the double-ring stiffeners.The reinforced cavity met operational requirements.
基金Project supported by the National High Technology Research and Development Program of China (Grant No. 2008AA03Z402)the Beijing Municipal Natural Science Foundation,China (Grant Nos. 4092007,4112006,4102003,and 4132006)+1 种基金the National Natural Science Foundation of China (Grant Nos. 61076044,61036002,61036009,and 60978067)the Doctoral Fund of the Ministry of Education of China (Grant No. 20121103110018)
文摘The polarization of traditional photonic crystal(PC) vertical cavity surface emitting laser(VCSEL) is uncontrollable,resulting in the bit error increasing easily.Elliptical hole photonic crystal can control the transverse mode and polarization of VCSEL efficiently.We analyze the far field divergence angle,and birefringence of elliptical hole PC VCSEL.When the ratio of minor axis to major axis b/a = 0.7,the PC VCSEL can obtain single mode and polarization.According to the simulation results,we fabricate the device successfully.The output power is 1.7 mW,the far field divergence angle is less than 10°,and the side mode suppression ratio is over 30 dB.The output power in the Y direction is 20 times that in the X direction.
文摘In this paper,the dynamic stress concentration and scattering of SH-waves by bi-material structures that possess an interface elliptic cavity are investigated.First,by using the complex function method,the Green's function is constructed.This yields the solution of the displacement field for an elastic half space with a semi-elliptic canyon impacted by an anti-plane harmonic line source loading on the horizontal surface.Then,the problem is divided into an upper and lower half space along the horizontal interface,regarded as a harmony model.In order to satisfy the integral continuity condition, the unknown anti-plane forces are applied to the interface.The integral equations with unknown forces can be established through the continuity condition,and after transformation,the algebraic equations are solved numerically.Finally,the distribution of the dynamic stress concentration factor(DSCF)around the elliptic cavity is given and the effect of different parameters on DSCF is discussed.
基金Project supported by the National Natural Science Foundation of China (Grant Nos 10574121, 90406024 and 10025420), Chinese Education Ministry and Chinese Academy of Sciences.
文摘This paper computes the conductance of an open ellipse cavity and discusses the effect of finite leads on conductance. The lead introduces mode coupling with bound states in the cavity which contributes to Fano resonant line shapes in conductance. By examining the resonant states in the cavity, the effects of state mixing and annular probability distribution of wave function due to the presence of leads are found. The results have been compared with the transport properties of other systems. The finite leads result in two effects, i.e. the evanescent mode contribution and additional oscillations, to the conductance.
基金Supported by China ADS Project(XDA03020000)National Natural Science Foundation of China(11475203)
文摘5-cell elliptical cavities have been selected for the main linac of the China Accelerator Driven subcritical System (C-ADS) in the medium energy section. According to the design, each cavity should be driven with radio frequency (RF) energy up to 150 kW by a fundamental power coupler (FPC). As the cavities work with high quality factor and high accelerating gradient, the coupler should keep the cavity from contamination in the assembly procedure. To fulfil the requirements, a single-window coaxial type coupler was designed with the capabilities of handling high RF power, class 10 clean room assembly, and heat load control. This paper presents the coupler design and gives details of RF design, heat load optimization and thermal analysis as well as multipacting simulations. In addition, a primary high power test has been performed and is described in this paper.