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Design Study on Higher Harmonic Cavity for ALS-U

Authors
  • Feng, Hanqi
  • Baptiste, Kenneth
  • De Santis, Stefano
  • Huang, Wenhui
  • Li, Derun
  • Liu, Zening
  • Luo, Tianhuan
  • Tang, Chuanxiang
Publication Date
Jun 24, 2019
Source
INSPIRE-HEP
Keywords
License
Unknown
External links

Abstract

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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