Poster

PUBDB-2018-02057

http://join2-wiki.gsi.de/foswiki/pub/Main/Artwork/join2_logo100x88.png Microwave instability and energy spread measurement via vertical dispersion bump in PETRA III

Keil, J.DESY* ; Sahoo, G.DESY* ; Wanzenberg, R.DESY* ; Novokshonov, A.DESY* ; Kube, G.DESY* ; Falkenberg, G.DESY* ; Chae, Y.-C. (Corresponding author)DESY* ; Ebert, M.DESY*

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.

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Contributing Institute(s):

1. Beschleunigerphysik (MPY)
2. Diagnose und Instrumentierung (MDI)
3. PETRA (MPE)
4. Experimentebetreuung PETRA III (FS-PE)
5. HF-Technik Elektronen (MHFe)

Research Program(s):

1. 631 - Accelerator R & D (POF3-631) (POF3-631)
2. 6G3 - PETRA III (POF3-622) (POF3-622)

Experiment(s):

1. Facility (machine) PETRA III

Appears in the scientific report 2018

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Linked articles:

http://join2-wiki.gsi.de/foswiki/pub/Main/Artwork/join2_logo100x88.png Contribution to a conference proceedings Chae, Y.-C. (Corresponding author)DESY* ; Keil, J.DESY* ; Sahoo, G. K.DESY* ; Wanzenberg, R.DESY* ; Ebert, M.DESY* ; Novokshonov, A.DESY* ; Kube, G.DESY* ; Falkenberg, G.DESY* ; Sprung, M.DESY* ; Dzhigaev, D.DESY* ; Westermeier, F.DESY*
Microwave instability and energy spread measurement via vertical dispersion bump in PETRA III
20189th International Particle Accelerator Conference, IPAC'18, VancouverVancouver, Canada, 29 Apr 2018 - 4 May 20182018-04-292018-05-04 3 pp. (2018) [10.3204/PUBDB-2018-02151]2018     Files BibTeX | EndNote: XML, Text | RIS

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