Author: Sigrist, M.J.
Paper Title Page
MOPPP061 Using RADIA to Model Superconducting Wigglers at the Canadian Light Source 699
  • C.K. Baribeau, L.O. Dallin, M.J. Sigrist, W.A. Wurtz
    CLS, Saskatoon, Saskatchewan, Canada
  The Canadian Light Source operates two superconducting wigglers: a 2 Tesla, 63 pole wiggler, and a 4 Tesla, 27 pole wiggler. Both SCWs have a negative impact on the injection efficiency. Beam based measurements indicate a larger than expected sextupole moment, and the 4T wiggler produces a large horizontal tune shift. To better understand these effects, computer models were developed for the SCWs using the magnetic modelling software package, RADIA. The RADIA models accurately predict the wiggler on-axis field strength and vertical tune shift. By introducing physical misalignments, the models can produce sextupole moments of the same order of magnitude as the measured quantities. However, the modelled horizontal tune shift is orders of magnitude smaller than the 4T wiggler’s observed tune shift. Various model parameters were investigated for their effect on horizontal tune shift, but the cause of the 4T wiggler’s large horizontal tune shift remains unknown.  
TUPPP001 Beam Based Measurements with Superconducting Wigglers at the Canadian Light Source with Applications to Nonlinear Beam Dynamics 1599
  • W.A. Wurtz, L.O. Dallin, M.J. Sigrist
    CLS, Saskatoon, Saskatchewan, Canada
  The Canadian Light Source (CLS) employs two superconducting wigglers for the production of hard x-rays. These wigglers cause a large decrease in injection efficiency. While such a decrease is not unexpected due to the large distortion to the linear optics, a correction to the linear optics does not restore injection efficiency. This inability to restore injection is not predicted by a kickmap model of the wiggler. We performed beam based measurements to construct a phenomenological, nonlinear model of the wiggler. Particle tracking with this wiggler model shows that the reduction in dynamic aperture is due to the amplitude dependent tune shift crossing a resonance, even with the linear optics corrected. Moving the tunes allows us to avoid this resonance and measurements at these tunes show that injection efficiency is not greatly affected by the wigglers.