WEA3 —  Oral Presentations (MC5)   (12-Oct-16   14:00—15:30)
Chair: V. Litvinenko, BNL, Upton, Long Island, New York, USA
Paper Title Page
WEA3IO01 Emittance Growth from Modulated Focusing in Bunched Beam Cooling 833
 
  • M. Blaskiewicz
    BNL, Upton, Long Island, New York, USA
  
  The low energy RHIC electron cooling (LEReC) project at Brookhaven employs a linac to supply electrons with kinetic energies from 1.6 to 2.6 MeV. Along with cooling the stored ion beam the electron bunches create a coherent space charge field which can cause emittance growth. This is the primary source of heating when the cooling is well tuned. An analytic theory of this process is presented and compared with simulations.  
slides icon Slides WEA3IO01 [4.160 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2016-WEA3IO01  
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WEA3IO02 Start-to-End Beam Dynamics Optimization of X-Ray FEL Light Source Accelerators 838
 
  • J. Qiang
    LBNL, Berkeley, California, USA
  
  State-of-the-art tools have been developed that allow start-to-end modeling of the beam formation at the cathode, to its transport, acceleration, and delivery to the undulator. Algorithms are based on first principles, enabling the capture of detailed physics such as shot-noise driven micro-bunching instabilities. The most recent generation of the IMPACT code, using multi-level parallelization on massively parallel supercomputers, now enables multi-objective parametric optimization. This is facilitated by recent advances such as the unified differential evolution algorithm*. The most recent developments will be described, together with applications to the modeling of LCLS-II**.
*J. Qiang, et al, http://www.optimization-online.org/DBFILE/2015/03/4796.pdf, submitted
**J. Qiang, et al, in preparation
 		 
slides icon Slides WEA3IO02 [10.928 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2016-WEA3IO02  
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WEA3CO03
 Efficiency of Feedbacks for Suppression of Transverse Instabilities of Bunched Beams  
 
  • A.V. Burov
    Fermilab, Batavia, Illinois, USA
  
  Which gain and phase have to be set for a bunch-by-bunch transverse damper, and at which chromaticity it is better to stay? How high are the remaining growth rates for the given gain and beam parameters? These questions are addressed by means of two Vlasov solvers: for high energy beams, the Nested Head Tail solver is used, while for strong space charge case, a new SChargeV code is exploited.  
slides icon Slides WEA3CO03 [6.007 MB]  
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WEA3CO04 Impedance Characterization and Collective Effects in the MAX IV 3 GeV Ring 843
 
  • G. Skripka, Å. Andersson, P.F. Tavares
    MAX IV Laboratory, Lund University, Lund, Sweden
  • F.J. Cullinanpresenter, R. Nagaoka
    SOLEIL, Gif-sur-Yvette, France
  
  Collective instabilities in the MAX IV 3 GeV storage ring are enhanced by the combination of high beam current, ultralow emittance and small vacuum chamber aperture. To mitigate instabilities by Landau damping and improve lifetime three passive harmonic cavities are installed to introduce synchrotron tune spread and bunch lengthening respectively. We present the results of studies of collective effects driven by the machine impedance. Bunch lengthening and detuning were measured to characterize the effective impedance and estimate the effect of the harmonic cavity potential. Investigations of collective effects as a function of parameters such as beam current and chromaticity are discussed.  
slides icon Slides WEA3CO04 [3.845 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2016-WEA3CO04  
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