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Detailed analysis of orbit and chromaticity correction techniques for optimizing dynamic aperture in particle accelerator systems. Results and recommendations included.
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Orbit and Chromaticity Correction andDynamic Aperture J. Barranco, W. Bartmann, Y. Papaphilippou PS2 meeting 11/02/2009
Outline • Orbit Correction • Error assignment • Positions of correctors and BPMs • Results for the orbit before/after correction • Chromaticity Correction • Positions of sextupoles • Off-momentum β-beating • Tuneshifts (amplitude, δp/p) • Dynamic Aperture and non-linear dynamics
Error Assignment • MisalignmentsDipoles: 0.3 mm shift and 0.3 mrad angle for all axes Quadrupoles: 0.2 mm shift for all axes • Field ErrorsDipoles ΔBL/Bρ : 0.510-3 All errors are Gaussian distributed with a cut-off at 3σ PS2 Orbit Correction
Positions of Correctors and BPMs (1/3) NMC Module MKH (black) MKV(red) • BPMs for both planes at each corrector. • 3 MKH + 4 MKV per module. • Non-symmetric distribution inside the module (Right-hand side MKH missing)
Positions of Correctors and BPMs (2/3) Dispersion Suppressor MKH (black) MKV(red) • 3 MKH + 3 MKV per Dispersion Suppressor. • BPMs for both planes at each corrector.
Positions of Correctors and BPMs (3/3) LSS MKH (black) MKV(red) • 6 MKH + 6MKV per LSS. • BPMs for both planes at each corrector.
Summary • Distribution of correctors • A total of 118 correctors and 118 BPMs will be installed.
Results before/after correction • Calculated with a sample of 500 machines • Qx = 13.25, Qy = 8.25 • Corrector kicks are below 1 mrad • All BPMs and Correctors are used PS2 Orbit Correction
Orbit before correction, hor.500 machines PS2 Orbit Correction
Orbit after correction, hor.500 machines PS2 Orbit Correction
Orbit before correction, vert.500 machines PS2 Orbit Correction
Orbit after correction, vert.500 machines PS2 Orbit Correction
Chromaticity Correction • 4 families of sextupoles of 0.4 m long. • First and Second order chromaticity corrected (PTC script used). • Three configurations studied • 4 families (MS1,MS2,MS3,MS4) • 2 families (MS2, MS3) • 2 families in series (MS1=-MS3,MS2=-MS4) • Max. sextupole strength 0.333 m-3 when correcting → max. 0.362 T pole tip field
Positions of Sextupoles NMC Module MS.1 MS.3 MS.2 MS.4 • 7 Sextupoles per module. • Non-symmetric distribution inside the module (Left-hand side Sextupole missing) • 2 families correcting horizontal (MS2 & MS4) • 2 families correcting vertical (MS1 & MS3)
Beta Beating 4 families 2 families 2 families in series
Tuneshift with amplitude 4 families 2 families (MS2/MS3) 2 families (Series) anhx(1,0,0,0) -259.806 -262.093781 -149.6878797 anhy(1,0,0,0) -9.5114 -22.911 40.0640378 anhx(0,1,0,0) -9.5114 -22.911 40.0640378 anhy(0,1,0,0) 165.417718 73.49865 216.5084655
Dynamic Aperture 4 families 2 families 2 families in series
Next Steps • Effect of the failure of monitors and correctors on orbit correction. • Introduce non-linear correction schemes. • Optimise sextupole strength and working point for optimal dynamic aperture. • Off-momentum dynamic aperture.