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Chao, H. C.

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MOOAAB04 Quadruple-bend Achromatic Low Emittance Lattice Studies 86
  • M.-H. Wang, H.-P. Chang, H. C. Chao, P. J. Chou, C.-C. Kuo
    NSRRC, Hsinchu
  • S.-Y. Lee, F. Wang
    IUCF, Bloomington, Indiana
  A quadruple-bend-achromatic (QBA) cell, defined as a super cell made of two double-bend (DB) cells with different outer and inner dipole bend angles, is found to provide a factor of two in lowering the beam emittance of electron synchrotron light sources. The ratio of bending angles of the inner dipoles to that of the outer dipoles is numerically found to be about 1.51.6 for an optimal low beam emittance in the isomagnetic condition. The QBA lattice provides an advantage over the double-bend achromat or the double-bend non-achromat in performance by providing some zero dispersion straight-sections and a small natural beam emittance. A lattice with 12 QBA cells with a preliminary dynamic aperture study serves as an example. The effects of the different types of insertion devices (ID) on the emittance in dispersive long straight and non-dispersive long straight are also simulated and reported.  
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TUPMN072 Current Status of Lattice Design and Accelerator Physics Issues of the 3 GeV Taiwan Synchrotron Light Source 1085
  • C.-C. Kuo, H.-P. Chang, H. C. Chao, P. J. Chou, W. T. Liu, G.-H. Luo, H.-J. Tsai, M.-H. Wang
    NSRRC, Hsinchu
  In the past years, we have been conducting a design work for a synchrotron light facility with low emittance storage ring in the intermediate energy range in NSRRC. A number of design options with different lattice structure types, circumferences, etc., are compared. We present one design case with 24-cell DBA structure and 486 m circumference. The associated accelerator physics issues are discussed.  
  • W. T. Liu, H.-P. Chang, H. C. Chao, P. J. Chou, C.-C. Kuo, G.-H. Luo, H.-J. Tsai, M.-H. Wang
    NSRRC, Hsinchu
  The demanding design features of Taiwan Photon Source (TPS), low emittance and small gap undulator vacuum vessels, cause Touschek scattering and gas scattering to play a major limitation role for beam lifetime. We calculate the Touschek lifetime based on the tracking procedure determining energy acceptance. The nonlinear synchrotron oscillation due to large second-order momentum compaction factor is included in the energy acceptance calculations. Small vertical ID gaps are imposed in the tracking procedure. Besides, the gas scattering lifetime is estimated with varying gas pressure. The possible improvement solutions for lifetime will be addressed.