Practical method for measurement and compensation of linear coupling driving term
We demonstrated a method with practical value for the measurement and global compensation of a complex coupling driving term C of linear difference resonance, using a turn-by-turn beam position monitor (BPM) at the SPring-8 storage ring. The method is based on the perturbation theory with the single...
| Main Authors: | , , , |
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| Format: | Article |
| Language: | English |
| Published: |
American Physical Society
2009-02-01
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| Series: | Physical Review Special Topics. Accelerators and Beams |
| Online Access: | http://doi.org/10.1103/PhysRevSTAB.12.024002 |
| Summary: | We demonstrated a method with practical value for the measurement and global compensation of a complex coupling driving term C of linear difference resonance, using a turn-by-turn beam position monitor (BPM) at the SPring-8 storage ring. The method is based on the perturbation theory with the single-resonance approximation. The accurate complex C was obtained from coefficients of the eigenmode expansion of the coupled betatron oscillation observed near a target linear difference resonance. The global compensation for the measured C was successfully carried out by determining optimal strengths of the two independent correcting skew quadrupoles for generating a counterterm -C without using empirical methods. Meanwhile, we then confirmed that the determined optimal strengths gave a minimum vertical beam size by scanning the strength of the correcting skew quadrupole field. To demonstrate the validity of our method, C was also measured while varying the strengths of the correcting magnets around the optimal values to generate deliberate skew quadrupole error fields. We confirmed that the measured values of C agreed with those coming from the deliberate error fields. |
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| ISSN: | 1098-4402 |