BBU(Beam breakup)instability once appeared in the early stage of 'Dragon-Ⅰ' LIA,which was excited by TM_(110)mode stimulated when the eccentric beam passed through the multi-functional cavity(MFC).The radio f...BBU(Beam breakup)instability once appeared in the early stage of 'Dragon-Ⅰ' LIA,which was excited by TM_(110)mode stimulated when the eccentric beam passed through the multi-functional cavity(MFC).The radio frequency characteristics of MFC were analyzed with three methods such as analytic calculation,numerical computation,and measurement.The frequency of the TM_(110)mode from these methods agreed with the experimental results,while the transverse coupling impedance was different from the experimental results by some times.The main BBU exciter was the big transverse coupling impedance of the MFC which could be concluded.A grid was designed to shield the gap of the MFC.The experiments show that the BBU was compressed and the high frequency oscillation disappeared.展开更多
The light transmission properties through two-dimensional photonic crystal waveguides based on coupling of square cavities are studied by the finite-difference time-domain technique.Through interlacing the adjacent ca...The light transmission properties through two-dimensional photonic crystal waveguides based on coupling of square cavities are studied by the finite-difference time-domain technique.Through interlacing the adjacent cavities along the direction vertical to the waveguide,the coupling distance between the adjacent cavities is extended,and the group velocity of the guiding modes can be slowed by five-fold compared with that in vacuum.Because of the different spatial field distributions of various resonant modes,the corresponding group velocities are also different for the same CROW structure.展开更多
文摘BBU(Beam breakup)instability once appeared in the early stage of 'Dragon-Ⅰ' LIA,which was excited by TM_(110)mode stimulated when the eccentric beam passed through the multi-functional cavity(MFC).The radio frequency characteristics of MFC were analyzed with three methods such as analytic calculation,numerical computation,and measurement.The frequency of the TM_(110)mode from these methods agreed with the experimental results,while the transverse coupling impedance was different from the experimental results by some times.The main BBU exciter was the big transverse coupling impedance of the MFC which could be concluded.A grid was designed to shield the gap of the MFC.The experiments show that the BBU was compressed and the high frequency oscillation disappeared.
基金supported by the National Natural Science Foundation of China(Grant Nos.10904176 and 11004169)the Fundamental Research Funds for the Central Universities+1 种基金the "985 Project"(Grant No.985-07012009)the "211 Project" of the Ministry of Education of China
文摘The light transmission properties through two-dimensional photonic crystal waveguides based on coupling of square cavities are studied by the finite-difference time-domain technique.Through interlacing the adjacent cavities along the direction vertical to the waveguide,the coupling distance between the adjacent cavities is extended,and the group velocity of the guiding modes can be slowed by five-fold compared with that in vacuum.Because of the different spatial field distributions of various resonant modes,the corresponding group velocities are also different for the same CROW structure.
