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@INPROCEEDINGS{Chae:405413,
      author       = {Chae, Yong-Chul and Keil, Joachim and Sahoo, Gajendra Kumar
                      and Wanzenberg, Rainer and Ebert, Michael and Novokshonov,
                      Artem and Kube, Gero and Falkenberg, Gerald and Sprung,
                      Michael and Dzhigaev, Dmitry and Westermeier, Fabian},
      title        = {{M}icrowave instability and energy spread measurement via
                      vertical dispersion bump in {PETRA} {III}},
      reportid     = {PUBDB-2018-02151},
      pages        = {3},
      year         = {2018},
      abstract     = {The recent measurement of bunch length versus current
                      indicated that the longitudinal impedance (Z/n) is 0.15 Ohm
                      in close agreement with the impedance model [1]. Naïve
                      application of Keil-Schnell criteria predicts that the
                      threshold of microwave instability at 0.25 mA. Since the
                      single bunch intensity is in the range of 0.2 – 2.5 mA
                      depending on the fill pattern of PETRA III, we expect to
                      observe the fill-pattern dependent energy spread according
                      to the theory. However, the 3rd generation light sources
                      comparable to PETRA III often reported the observation which
                      was much greater than the theoretical one. In order to
                      induce the beam size variation we had used skew quadrupoles
                      to generate the dispersion in vertical plane. In particular
                      we made dispersion bump at the undulator sector so that we
                      were able to use the x-ray optics for the precise
                      determination of small vertical beam size. In this paper we
                      report the experimental setup and measurement data with the
                      estimate on the instability threshold. We also report the
                      vertical emittance and energy spread based on the x-ray beam
                      size measurement as well as the rf signal which was excited
                      by the beam at the longitudinal feedback cavity.},
      month         = {Apr},
      date          = {2018-04-29},
      organization  = {9th International Particle Accelerator
                       Conference, Vancouver (Canada), 29 Apr
                       2018 - 4 May 2018},
      cin          = {MPY / FS-PE / MPE},
      cid          = {I:(DE-H253)MPY-20120731 / I:(DE-H253)FS-PE-20120731 /
                      I:(DE-H253)MPE-20120731},
      pnm          = {631 - Accelerator R $\&$ D (POF3-631) / 6G3 - PETRA III
                      (POF3-622)},
      pid          = {G:(DE-HGF)POF3-631 / G:(DE-HGF)POF3-6G3},
      experiment   = {EXP:(DE-H253)PETRAIII(machine)-20150101},
      typ          = {PUB:(DE-HGF)8},
      doi          = {10.3204/PUBDB-2018-02151},
      url          = {https://bib-pubdb1.desy.de/record/405413},
}