Author: Carvelli, J.
Paper Title Page
MOPLM17 Longitudinal Impedance Modeling of APS Particle Accumulator Ring with CST 140
  • C. Yao, J. Carvelli, K.C. Harkay, L.H. Morrison
    ANL, Lemont, Illinois, USA
  • D. Hui
    University of Arizona, Tucson, Arizona, USA
  • J.S. Wang
    Dassault Systems Simulia, Waltham, Massachusetts, USA
  Funding: Work supported by the U.S. Department of Energy, Office of Science, under Contract No. DE-AC02-06CH11357.
The APS-U (APS upgrade) ring plans implement a "swap out" injection scheme, which requires a injected beam of 15.6 nC single-bunch beam. The Particle Accumulator Ring (PAR), originally designed for up to 6 nC charge, must be upgraded to provide 20 nC single bunch beam. Our studies have shown that bunch length of the PAR beam, typically 300 ps at lower charge, increases to 800 ps at high charge due to longitudinal instabilities, which causes low injection efficiency of the downstream Booster ring. We completed beam impedance of all the PAR vacuum components recently with CST wakefield solver. 3D CAD models are directly imported into CST and various techniques were explored to improve and verify the results. The results are also cross-checked with that from GdfidL and Echo simulation. We identified 23 bellow- and 24 non-bellow flanges that contribute to as much as 50% of the total loss factor. We are considering upgrade options to reduce over all beam loading and longitudinal impedance. Beam tracking simulation is in progress that including the longitudinal impedance results from the simulations. We report the results and methods of the CST impedance simulations.
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About • paper received ※ 22 August 2019       paper accepted ※ 05 September 2019       issue date ※ 08 October 2019  
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