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PS2 FODO Lattice. PS2 Meeting, 22-Aug-07 Wolfgang Bartmann. Outline. Actual Lattice with 2 dipoles per halfcell Motivation for n bend = 2 Cell design Performance Suppressor Design Parameters Lattice with additional quadrupole families: Asymmetric Symmetric Conclusion.
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PS2 FODO Lattice PS2 Meeting, 22-Aug-07 Wolfgang Bartmann
Outline • Actual Lattice with 2 dipoles per halfcell • Motivation for nbend = 2 • Cell design • Performance • Suppressor Design • Parameters • Lattice with additional quadrupole families: • Asymmetric • Symmetric • Conclusion PS2 Meeting: FODO Lattice
Initial Lattice – Motivation • Former lattice had three dipoles per halfcell with 6 LSS cells at least one cell more for beam transfer and the beam dump was required • FODO cell with two dipoles per halfcell showed up to meet best the new conditions: 7 LSS cells for the same circumference enforces smaller cell lengthes which is provided by nbend = 2 nbend = 3 nbend = 2 nbend = 3 nbend = 2 PS2 Meeting: FODO Lattice
ss1 = 1.6 m ss1 = 1.6 m Actual Lattice – Cell design and improvement • Lattice with nbend = 2 and standard dispersion suppressor was dispersion free in the LSS for μ = 103 deg high tune! • By swapping the longer and shorter drift spaces in the lattice, the phase advance was lowered while keeping the dispersion free sections; the longer drift of 1.6 m is now after the quadrupoles: • The lattice is tunable between Q = 14.1 – 14.9, i.e. around 90 deg phase advance PS2 Meeting: FODO Lattice
Actual Lattice – Performance • 7 LSS cells, 22 arc cells, 2 dipoles per half cell • 2 quadrupole families • μ = 88 deg, gammatr = 11.4 • Missing magnet suppressor, positions of dipoles adjusted to get working point below 90 deg for the phase advance PS2 Meeting: FODO Lattice
Actual Lattice – Suppressor Design PS2 Meeting: FODO Lattice
Actual Lattice - Parameters PS2 Meeting: FODO Lattice
Additional quadrupole families (Asym.) • Actual lattice used, μ = 89 deg • 10 quadrupole families: • 2 fam. for the LSS • 2 fam. for the arc • 6 fam. to match the optical functions from the LSS to the arc PS2 Meeting: FODO Lattice
Additional quadrupole families (Sym.) • Lattice with symmetric arrangement of the dipoles in the cell shows the ideal behaviour of the dispersion in the arc • μ = 78 deg, 10 quadrupole families PS2 Meeting: FODO Lattice
Conclusion Three variants: • Actual FODO Lattice with 2 quadrupole families provides dispersion free LSS at about 90 deg phase advance (Q = 14.1 - 14.9) • Actual FODO Lattice (asymmetric) with additional quadrupole families (in total 10) allows perfect matching of the dispersion at 90 degThe asymmetric Lattice with additional quadrupole families gives only slightly better dispersion performance in the arc than the FODO Lattice with two families which may not justify the increase in cost and operation complexity • FODO Lattice with symmetric arrangement of the dipoles in the cells and 10 quadrupole fam. matches dispersion exactly to zero at 78 deg The symmetric Lattice looses the long drift space close to the quadrupoles which could be used to place correctors PS2 Meeting: FODO Lattice