Author: Blednykh, A.
Paper Title Page
MOPPP090 Spectral Performance of Segmented Adaptive-Gap In-Vacuum Undulators for Storage Rings 765
  • O.V. Chubar, J. Bengtsson, A. Blednykh, C.A. Kitegi, G. Rakowsky, T. Tanabe
    BNL, Upton, Long Island, New York, USA
  • J.A. Clarke
    STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom
  Funding: US DOE, Contract No. DE-AC02-98CH10886.
We propose an approach to the optimization of segmented in-vacuum undulators, in which different segments along an undulator may have different gaps and periods. This enables close matching between the gaps and the vertical "envelope" of electron beam motion in a storage ring straight section (carefully satisfying the associated vertical "stay clear" constraint) and, at the same time, precise tuning of all the segments to the same fundamental photon energy. Thanks to this, the vertical gaps in segments located closer to straight section center can be smaller than at extremities, and so the entire undulator structure can offer better magnetic performance, compared to the case of a standard undulator with constant gap (and period) over its length. We will present magnetic field, radiation flux, brightness and intensity calculation results for such segmented adaptive-gap in-vacuum undulators and demonstrate their gain in spectral performance over standard in-vacuum undulators, both for room-temperature and cryo-cooled realizations.
TUPPP042 Passive Landau Cavity Effects in the NSLS-II Storage Ring 1701
  • G. Bassi, A. Blednykh, S. Krinsky
    BNL, Upton, Long Island, New York, USA
  Funding: Work supported by DOE contract No: DE-AC02-98CH10886.
In new 3rd generation synchrotron light sources with small transverse emittance, higher harmonic cavities (Landau cavities) are installed for bunch lengthening to increase the Touschek lifetime, and to provide Landau damping for beam stability. In this contribution we study the effects of passive Landau cavities in the NSLS-II storage ring for arbitrary fill-patterns with the OASIS tracking code.
TUPPP043 Analysis of Coupled Bunch Instabilities in the NSLS-II Storage Ring with a 7-cell PETRA-III RF Structure 1704
  • G. Bassi, A. Blednykh, S. Krinsky, J. Rose
    BNL, Upton, Long Island, New York, USA
  Funding: Work supported by DOE contract No: DE-AC02-98CH10886.
A 7-cell PETRA-III cavity is considered to be installed for the commissioning Phase 1 in the NSLS-II storage ring at an average current of 25mA. In this contribution we study transverse and longitudinal coupled-bunch instabilities that may be driven by the higher order modes of the 7-cell PETRA-III cavity. The instability thresholds are calculated with the OASIS tracking code, with parameters of the bare lattice (no damping wigglers and Landau cavities). We study multibunch configurations with arbitrary fill-patterns and discuss the slow head-tail effect at positive chromaticity to increase the transverse instability thresholds.
WEPPR098 Two Dimensional Impedance Analysis of Segmented IVU 3168
  • A. Blednykh, G. Bassi, J. Bengtsson, O.V. Chubar, C.A. Kitegi, T. Tanabe
    BNL, Upton, Long Island, New York, USA
  Funding: Work supported by DOE contract No: DE-AC02-98CH10886
Segmented Adaptive-Gap In-Vacuum Undulator (IVU) with variable magnetic gap along z-axis is considered as an alternative to the Constant Gap IVU (7mm gap) for the NSLS-II storage ring. The length of the Constant Gap IVU for a given minimum gap is limited by the beam stay clear aperture. With the new conceptual design of IVU the magnetic gap can be varied along z-axis and its minimum gap can be reduced down to 5.25mm in the center of the structure for the same stay clear aperture. Beam impedance becomes an important issue since the new design consists of several magnet gaps. Wakepotentials and impedances have been analyzed for a new type of IVU and the results compared with data for the reference geometry which is the Constant Gap IVU.