Diffraction of a two-dimensional （2D） semi-circular cavity in a half-space under incident SH-waves is studied using the classic wave function expansion method with a new de-coupling technique. This so-called ＂impro...Diffraction of a two-dimensional （2D） semi-circular cavity in a half-space under incident SH-waves is studied using the classic wave function expansion method with a new de-coupling technique. This so-called ＂improved cosine half- range expansion＂ algorithm exhibits an excellent performance in reducing displacement residual errors at two rim points of concern. The governing equations are developed in a manner that minimizes the residues of the boundary conditions. Detailed derivation and analysis procedures as well as truncation of infinite linear governing equations are presented. The semi-circular cavity model presented in this paper, due to its simple profile, is expected to be used in seismic wave propagation studies as a benchmark for examining the accuracies of various analytical or numerical methods for mixed-boundary wave propagation problems.展开更多
A higher-harmonic cavity will be used to increase the beam lifetime and suppress coupled-bunch instabilities for Hefei Light Source-II. In this paper, results simulated by the particle-tracking model confirm that tuni...A higher-harmonic cavity will be used to increase the beam lifetime and suppress coupled-bunch instabilities for Hefei Light Source-II. In this paper, results simulated by the particle-tracking model confirm that tuning in the harmonic cavity may suppress the parasitic coupled-bunch instabilities. The factors calculated for lifetime improvement are larger than 2.5. The 3rd and 4th harmonic cavities have been designed. In particular, the absorbers and antenna couplers are applied in harmonic cavities to damp the higher order modes. Finally, the 4th harmonic cavity similar to the Duke＇s RF cavity will be used for HLS-II.展开更多
A passive higher harmonic cavity （HHC） will be used in the Hefei Light Source II Project （HLS- II） to lengthen the bunch and consequently increase the beam lifetime dominated by Touschek scattering. The effects of...A passive higher harmonic cavity （HHC） will be used in the Hefei Light Source II Project （HLS- II） to lengthen the bunch and consequently increase the beam lifetime dominated by Touschek scattering. The effects of constant voltage and constant detuning have been calculated and compared over the operating current from 0.4 to 0.2 A on the bunch lengthening for the passive normal conducting harmonic cavity system in HLS-II. The results show that the bunch shape has less change and the lifetime improvement factors are not less than 2.7 over the beam currents for the constant voltage case. The constant voltage operating scheme may be applied to our machine.展开更多
文摘Diffraction of a two-dimensional （2D） semi-circular cavity in a half-space under incident SH-waves is studied using the classic wave function expansion method with a new de-coupling technique. This so-called ＂improved cosine half- range expansion＂ algorithm exhibits an excellent performance in reducing displacement residual errors at two rim points of concern. The governing equations are developed in a manner that minimizes the residues of the boundary conditions. Detailed derivation and analysis procedures as well as truncation of infinite linear governing equations are presented. The semi-circular cavity model presented in this paper, due to its simple profile, is expected to be used in seismic wave propagation studies as a benchmark for examining the accuracies of various analytical or numerical methods for mixed-boundary wave propagation problems.
基金Supported by National Natural Science Foundation of China (10675116)Major State Basic Research Development Programme of China(2011CB808301)
文摘A higher-harmonic cavity will be used to increase the beam lifetime and suppress coupled-bunch instabilities for Hefei Light Source-II. In this paper, results simulated by the particle-tracking model confirm that tuning in the harmonic cavity may suppress the parasitic coupled-bunch instabilities. The factors calculated for lifetime improvement are larger than 2.5. The 3rd and 4th harmonic cavities have been designed. In particular, the absorbers and antenna couplers are applied in harmonic cavities to damp the higher order modes. Finally, the 4th harmonic cavity similar to the Duke＇s RF cavity will be used for HLS-II.
基金Supported by National Natural Science Foundation of China (10675116)Major State Basic Research Development Programme of China (2011CB808301)
文摘A passive higher harmonic cavity （HHC） will be used in the Hefei Light Source II Project （HLS- II） to lengthen the bunch and consequently increase the beam lifetime dominated by Touschek scattering. The effects of constant voltage and constant detuning have been calculated and compared over the operating current from 0.4 to 0.2 A on the bunch lengthening for the passive normal conducting harmonic cavity system in HLS-II. The results show that the bunch shape has less change and the lifetime improvement factors are not less than 2.7 over the beam currents for the constant voltage case. The constant voltage operating scheme may be applied to our machine.
