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Masaki, M.

Paper Title Page
THPC026 Measurement of Complex Coupling Driving Term of Linear Difference Resonance Using Turn-by-turn Beam Position Monitors 3035
 
  • M. Masaki, K. Soutome, S. Takano, M. Takao
    JASRI/SPring-8, Hyogo-ken
 
  X-Y emittance coupling is one of the important measures of beam quality in an electron storage ring for high brilliant light source. We have developed a method of measuring complex coupling driving term C of linear difference resonance using turn-by-turn beam position monitors (BPMs), assuming the perturbation theory with the single resonance approximation. Since both amplitude and phase of the driving term are derived, we can uniquely determine the strength of two-degree-of-freedom skew quadrupole magnets for correction of the linear resonance coupling. Before the correction, the driving term was measured by the developed method at the SPring-8 storage ring where small skew quadrupole components are distributed as error magnetic fields. On the other hand, the linear resonance coupling was corrected using the counter skew quadrupole magnets, the strength of which was adjusted to minimize vertical beam size near the linear difference resonance. The measured driving term C was broadly consistent with the counter term calculated from the adjusted strength of skew quadrupole magnets for the coupling correction.