TUA1WB —  WG-B   (06-Mar-18   09:00—10:30)
Chair: M. Borland, ANL, Argonne, Illinois, USA
Paper Title Page
Survey of Injection Schemes for Next-generation Light Source Rings  
  • Z. Duan
    IHEP, Beijing, People's Republic of China
  Next-generation storage ring-based light sources will be based on the multi-bend achromat (MBA) lattice, as successfully demonstrated in MAX-IV. Such designs promise substantial brightness improvements compared to third-generation light sources, while there is likely to be a trade-off between the optimized brightness, available dynamic aperture for injection and local momentum acceptance related to beam lifetime. Different injection schemes have been proposed for these designs with different requirements on the ring dynamic aperture. In fact, the choice of injection schemes will significantly affect the figure of merit in the lattice optimisation and even the overall design of the facility. This talk will survey these injection schemes, their merits and challenges, and the R&D efforts involved.  
slides icon Slides TUA1WB01 [3.490 MB]  
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Compensation of Transient RF Voltage in a Double RF System Using a Kicker Cavity  
  • N. Yamamoto, S. Sakanaka, T. Takahashi
    KEK, Ibaraki, Japan
  In quasi diffraction-limited synchrotron light sources especially in the low-to-medium energy range, emittance growth due to intrabeam scattering (IBS) is a serious concern. To mitigate the IBS, a double rf system is used to lengthen the beam bunches. In the double RF system, the performance of bunch lengthening is limited by the transient beam-loading effect which is induced by bunch gaps in the fill pattern. Even if the superconducting (SC) harmonic cavities (HCs) are used, the performance of bunch lengthening is limited when the bunch gap is large. To improve their performances, we propose the use of a single "kicker" cavity having low loaded Q. The "kicker" cavity provides an rf voltage that is comparable to the fluctuating rf voltages in the main and harmonic cavities, and mitigates the phase shift of beam bunches over the bunch train, while keeping its required generator power modest. As a results of our numerical investigation, the significantly improvement of the bunch lengthening performance can be expected. We will present the concept of this technique and show expected bunch-lengthening performances.  
slides icon Slides TUA1WB02 [11.854 MB]  
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Injection Transient Observation via Bunch-by-bunch Beam Size Measurement System  
  • H.J. Chen, J. Chen, B. Gao, Y.B. Leng
    SINAP, Shanghai, People's Republic of China
  A bunch-by-bunch beam size measurement system has been developed at SSRF as a sub-system of 6-dimension bunch-by-bunch diagnostic system, which is an attempt for global bunch information capturing during instabilities by SSRF BI group. The system is composed of direct-imaging optical front-end, high-speed photomultiplier array detector, signal amplifiers and high sampling rate oscilloscope as signal acquisition method. An injection transient process has been successfully captured based on 4-channels signal with strongly bunch position and horizontal beam size oscillation after injection point as betatron oscillation of SSRF storage ring. It demonstrates the bunch-by-bunch measurement capability of the system, which will be used for other fast instabilities monitoring and analysis. Further 16 channels detection using synchronized digitizers and other optimizations is also under developing for high size resolution.  
slides icon Slides TUA1WB03 [8.636 MB]  
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