| Paper |
Title |
Page |
| WEPC130 |
Shimming Correction of Dynamic Multipole Effects on Apple-II Type EPUs at the ALS
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2311 |
| |
- C. Steier, A. Madur, S. Marks, S. Prestemon, T. Scarvie, D. Schlueter, W. Wan
LBNL, Berkeley, California
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Elliptically Polarizing Undulators that provide full photon polarization control also have fast, intrinsic transverse roll-off of the magnetic field. The roll-off is particularly fast for vertical polarization settings, and can have big detrimental effects on the nonlinear single particle dynamics. Particularly low and medium energy light sources and long period EPUs are prone to those effects. The three existing 50mm period EPUs at the ALS have been retrofitted with shims to correct for these dynamic multipole effects and a new 90mm period device which otherwise would have caused a huge reduction in dynamic aperture has been shimmed before installation. Simulations and beam measurements will be presented, including frequency map measurements.
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| WEPC155 |
Experimental Characterization of Permanent Magnet Harmonic Corrector Rings
|
2371 |
| |
- A. Madur, S. Marks, S. Prestemon, D. Schlueter
LBNL, Berkeley, California
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| |
A total of three permanent magnet chicane magnets have been installed at the Advanced Light Source (ALS) at the Lawrence Berkeley National Laboratory. The magnet design incorporates counter-rotating permanent magnet pairs with trim coils. The purpose is to provide a fixed angular separation between two successive elliptically polarizing undulator (EPU) photon fans and to correct steering perturbation resulting from EPU polarization state and gap changes. This paper presents a method for the determination of the permanent magnets parameters and setting relative orientations of the rotors by performing magnetic measurements with rotating coils. The measurement method will be developed and illustrated with experimental data from the measurement of a 16 cylinder permanent magnet harmonic corrector ring.
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