Keyword: higher-order-mode
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WEPRB081 Design Study on Higher Harmonic Cavity for ALS-U cavity, impedance, simulation, wakefield 3011
  • H.Q. Feng, K.M. Baptiste, S. De Santis, D. Li, T.H. Luo
    LBNL, Berkeley, California, USA
  • H.Q. Feng, W.-H. Huang, Z.N. Liu, C.-X. Tang
    TUB, Beijing, People’s Republic of China
  Funding: Director of Office of Science of the U.S. Department of Energy under Contract No. DE-AC02-05CH11231
The ALS upgrade (ALS-U) to a diffraction-limited light source [1] depends on the ability to lengthen the stored bunches to limit the emittance growth and increase the beam life time. Higher harmonic cavities (HHCs), also known as Landau cavities, have been proposed to in-crease beam lifetime and Landau damping by lengthen-ing the bunch. We present an optimized 1.5 GHz normal conducting HHC design for the ALS-U with a supercon-ducting-like geometry using multi-objective genetic algorithm (MOGA) for lower R/Q. The optimization goal is to reach the required shunt impedance while maintain-ing a relatively high Q value of the cavities. To minimize the coupled bunch instabilities, higher-order mode (HOM) of the HHC as well as corresponding impedance are explored and characterized.
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About • paper received ※ 16 May 2019       paper accepted ※ 21 May 2019       issue date ※ 21 June 2019  
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