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Nagaoka, R.

Paper Title Page
MOPAN009 Transverse Feedback Development at SOLEIL 161
  • R. Nagaoka, L. Cassinari, J.-C. Denard, J.-M. Filhol, N. Hubert, M.-P. Level, P. Marchand, C. Mariette, F. Ribeiro, R. Sreedharan
    SOLEIL, Gif-sur-Yvette
  • K. Kobayashi, T. Nakamura
    JASRI/SPring-8, Hyogo-ken
  With reduced vertical chamber aperture adopted all around the machine, the transverse impedance for the SOLEIL ring is enhanced both in its resistive-wall and broadband content. The predicted instability threshold currents being significantly low as compared to the nominal current in multibunch and in several single bunch modes, a decision was taken to install a digital bunch by bunch feedback system, with an aim to make it operational since the beginning of the storage ring operation. The system implemented comprises components developed elsewhere, particularly the FPGA processor of SPring-8, chosen among different possible solutions. Using a BPM and a stripline in the diagonal mode, a single unit of the FPGA processor board has shown to successfully suppress resistive-wall and ion induced multibunch instabilities in either one or both transverse planes. On top of the system characteristics, the paper discusses details of the obtained performance, as well as future extensions to overcome the encountered limitations.  
WEOBC01 Beam Instability Observations and Analysis at SOLEIL 2019
  • R. Nagaoka, L. Cassinari, M.-E. Couprie, M. Labat, M.-P. Level, C. Mariette, R. Sreedharan
    SOLEIL, Gif-sur-Yvette
  Due to reduced vertical chamber aperture around the machine, the impedance was systematically evaluated and optimized 3D-wise at SOLEIL during the design stage, whose budget was then utilized to predict instability thresholds for multi and single bunches. These theoretical calculations are compared with observed instabilities. Transverse multibunch current thresholds are followed as a function of chromaticity, identifying the transition of different head-tail regimes that reflects the broadband impedance spectrum. Although low thresholds due to resistive-wall are basically confirmed, its combined effect with ion-induced instability is found to be significant, exhibiting a strong beam filling pattern dependence. To analyse the involved dynamics, a multibunch tracking code is developed in a structure that allows parallel computations with a cluster of processors. The obtained results are compared with empirical data. Analysis of single bunch instabilities is also made with an aim to identify the enhanced reactive impedance due to NEG coating.  
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TUPMN009 Commissioning of the SOLEIL Synchroton Radiation Source 932
  • A. Nadji, J. C. Besson, F. Bouvet, P. Brunelle, A. Buteau, L. Cassinari, M.-E. Couprie, J.-C. Denard, J.-M. Filhol, C. Herbeaux, J.-F. Lamarre, V. Le Roux, P. Lebasque, M.-P. Level, A. Loulergue, P. Marchand, L. S. Nadolski, R. Nagaoka, B. Pottin, M.-A. Tordeux
    SOLEIL, Gif-sur-Yvette
  The French 3rd generation synchrotron light source, SOLEIL, was successfully commissioned in 2006. The Linac and the Booster are operational at their design performances. During the early phase of the storage ring commissioning, the essential design parameters were reached very quickly while the project incorporates some innovative techniques such as the use of a superconducting RF cavity, solid state RF amplifiers, NEG coating for all straight parts of the storage ring and new BPM electronics. Prior to the start of the commissioning, some insertion devices and most of the insertion devices low gap vacuum vessels, including 10 mm inner vertical aperture vessels for the Apple-II type, were installed on the ring. The main results of the commissioning will be reviewed here, including discussion on diagnostics performances, orbit stability and control, optics correction, Top-up and the challenges in achieving operational status. The 10 beamlines of phase 1 are now under commissioning and regular user operation will start by spring 2007.