• Y.D. Joo, T. Ha, C. Kim, C.D. Park, S.J. Park
  PAL, Pohang, Kyungbuk

A superconducting RF cavity is used in the storage ring of the Pohang Light Source (PLS) upgrade project (PLS-II) at Pohang Accelerator Laboratory (PAL) for increasing the electron beam current and energy from 2.5GeV/200mA to 3.0GeV/400mA. In order to meet the requirement of lower beam emittance and higher photon energies, as well as more straight sections for insertion devices, the vacuum chambers in the storage ring need to be reconstructed. To control the spurious harmonic resonances' effect to beam position monitors (BPMs) in the PLS and PLS-II storage ring vacuum chamber, the TE mode distribution in vacuum chambers has been analyzed by both numerical simulation and experiment. Based on this analysis, the proper method to control the strength of TE mode at the position of BPMs is suggested.