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Update on design of final TALs in the CLIC Drive Beam. R. Apsimon, J. Esberg. Optimisation techniques. Local optimisation Each cell optimised separately Easy to tune Poor energy acceptance Sextupoles don’t help a lot Global optimisation Match all sextupoles and quadrupoles
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Update on design of final TALs in the CLIC Drive Beam R. Apsimon, J. Esberg
Optimisation techniques • Local optimisation • Each cell optimised separately • Easy to tune • Poor energy acceptance • Sextupoles don’t help a lot • Global optimisation • Match all sextupoles and quadrupoles • Very good energy acceptance • Very weak sextupoles needed
20 sextupoles used • 4 sextupoles per arc cell • Maximum pole-tip field ~0.018 T
Emittance growth vs sextupole strength: MADX-PTC tracking Horizontal Vertical Longitudinal
PLACET tracking: longitudinal phase space: no synchrotron radiation
Emittance growth vs sextupole strength: PLACET tracking Horizontal Vertical Longitudinal