Speaker
Description
The Rapid Cycling Synchrotron (RCS) of the Electron–Ion Collider (EIC) will accelerate polarized electrons up to 18 GeV at a rate of 1 Hz. Dynamic multipoles driven by eddy currents in the vacuum chamber can significantly affect beam dynamics and degrade polarization transmission and therefore require careful study. We begin with the well-known solution by S. Y. Lee for dynamic multipoles driven by eddy currents in the vacuum chamber of a ramped normal-conducting dipole magnet, modeled as a pair of infinitely permeable, non-conducting parallel plates. Using conformal transformations, we derive compact expressions for dynamic multipoles in higher-order ramped magnets, i.e., quadrupoles, sextupoles, etc., restricting attention to axially symmetric vacuum chambers. We then compare these results with FEM simulations and study the effects of practical yoke geometry and chamber-to-magnet misalignment. Finally, we estimate the relevant dynamic multipoles expected in the RCS magnets and discuss their implications for beam dynamics and polarization preservation during the energy ramp.
Funding Agency
Work supported by Brookhaven Science Associates, LLC under Contract No. DE-SC0012704 with the US Department of Energy
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