We analyse higher order modes in the 3.9 GHz bunch shaping cavities recently installed in the FLASH facility at DESY. We report on recent experimental results on the frequency spectrum from probe based measurements made at CMTB at DESY. These are compared to those predicted by finite difference and finite element computer codes. This study is focused mainly on the dipole component of the multi-pole expansion of the wakefield.. The modes are readily identifiable as single-cavity modes provided the frequencies of these modes are below the cut-off of the inter-connecting beam pipes. The modes above cut-off are coupled to the 4 cavities and are distinct from single cavity modes
@article{arxiv.1006.0085,
title = {Higher Order Modes in Third Harmonic Cavities for XFEL/FLASH},
author = {I. R. R. Shinton and N. Baboi and N. Eddy and T. Flisgen and H. W. Glock and R. M. Jones and N. Juntong and T. N. Khabiboulline and U van Rienen and P. Zhang},
journal= {arXiv preprint arXiv:1006.0085},
year = {2014}
}
Comments
Presented at First International Particle Accelerator Conference, IPAC'10, Kyoto, Japan, from 23 to 28 May 2010