Dynamic Aperture Considerations for Large Superconducting Synchrotrons

  • F. Willeke
Part of the Ettore Majorana International Science Series book series (EMISS, volume 53)


Nonlinear forces introduce a limit for stable betatron oscillation amplitudes of the particles of an accelerator beam. Beyond this limit, the particle amplitudes will grow until the wall of the beam pipe is reached and loss occurs. That is why the focussing and guide fields of accelerators are designed to be as linear as possible. On the other hand, a perfectly linear machine would not work. Nonlinear sextupole fields have to be installed in order to compensate chromatic effects1. This turns the linear lenses effectively into achromats. The impact of the nonlinearity of these sextupoles and corresponding performance limitations have to be tolerated. Thus in every large accelerator there is a limit for the amplitude of stable betatron oscillations. Chromaticity correcting sextupoles present a natural scale to determine limitations for additional nonlinearities which arise from imperfections of the magnetic guide and focussing fields. Unfortunately, the strength of these parasitic nonlinearities becomes comparable to or even larger than the chromaticity sextupoles if the synchrotrons become considerable larger than existing machines.


Persistent Current Beam Pipe Nonlinear Force Quadrupole Magnet Field Error 
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Copyright information

© Plenum Press, New York 1990

Authors and Affiliations

  • F. Willeke
    • 1
  1. 1.Deutsches Elektronen-Synchrotron DESYHamburg 52Germany

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