Post on 05-Jan-2016
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NSLS-II Lattice Design
1. TBA-24 Lattice Design - Advantages and shortcomings
Low emittance -> high chromaticity -> small DA from nonlinear dynam.
TBA dispersion region major limitation for reducing sextupole strength
2. DBA-32 Lattice Design - Damping Wigglers for Emittance Control
Linear design with working point for non-linear DA optimization
ID’s eXtra long (15m) and standard Length (6m)
Dipole designed for damping wigglers
DA and frequency map for bare lattice with 11 sextupole families
DA with alignment tolerances
3. Summary of Lattice Parameters for DBA-32(8)
S. Kramer, J. Bengtsson, S. Krinsky, T. Shaftan, D. Wang, L. Yun, I. Pinayev
May 11,2006
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TBA-24 Lattice Design
TBA-24 Lattice Design worked on for ~2 years
Reached 1.5 nm emittance in 630m but DA small, 2.2nm 758m
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TBA-24 Lattice Features
TBA-24 Lattice very flexible
Lower emittance per period than DBA, 24 period εx >0.38 nm
Tune variable over big range for constant emittance
α1 variable without breaking symmetry of lattice, i.e. isochronous tune
TBA-24 Lattice has small dispersion like DBA-48
Even with low chromaticity (~2.2/period) sextupoles strong
DA low and challenging to expand without giving up on low emittance
Minimum number of ID’s for users
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Reconsider DBA Lattice Option
Higher emittance/period more periods, more ID’s
Use extra ID’s for emittance control with damping wigglers
Wigglers have potentially less DA impact and counter users changes
Optimize emittance damping with low field dipoles
Dispersion region has freedom to increase dispersion, reducing chromatic sextupole strength
Lesson from TBA-24 study of ID Quadruplet for phase and beta functions matching for undulators
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Basic DBA-32 Cell 6m ID
Qx= 1.09 (1.13), ξx = -3.38 (-3.6) εx =1.66 (1.74)nm (ESRF@3GeV)
Qy= 0.72 (0.35), ξy = -1.25 (-1.01) C= 868 (845)m +35.2m in dipoles
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Two Types of ID with SP=8
ID’s = 15m +3* 6m C=929.8m εx =1.66 nm ξx,y = -3.26,-1.13/per
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Emittance vs Damping Wiggler B-field
Energy Spread vs Wiggler Field
Lw = 54m
ρw = 1.4*Bρ/Bw
Bdipole=0.33T
Bdipole=0.66TBdipole=0.66T
Bdipole=0.33T
Emittance change vs Wiggler Field
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Damping Wigglers in 4-15m ID
Power radiated could exceed 125KW in one 15 ID, canting will reduce threat to front end components and yield 3 or more user beams
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DBA32 Working Point SP=8
Tune selected from DA scan and optimized for reduced Closed Orbit Amplification
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Closed Orbit Amplification Factors
Quadrupole alignment tolerance reduced by small Beta functions and tune
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DBA32 Tune Scan for Cell
At each tune value: driving terms were optimized to 3rd order and DA area calculated yields peak near (4.29,2.615)
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DA for Tune and 11 Sext. Families
Frequency map shows diffusion at high order resonances and tune shifts
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Alignment tolerances on Quads and Sextupoles <100μm corrected
DA and momentum aperture for constant momentum error adequate for injection
Asymmetry in momentum aperture from high order chromaticity and dispersion
Tolerances on BPM to sextupole centering okay for < 30μm
7 BPM and 7 Corrector magnets / period
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Adding Synchrotron Oscillations Adding Synchrotron Oscillations
DA maintains reasonable values but momentum aperture more symmetric
For random alignment tolerances < 100 μm with correction injection okay
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NSLS-II Lattice ParametersNSLS-II Lattice Parameters
Energy 3 3.6 GeV
Io (Total Current) 0.500 0.241 Amps
Circumference 929.805 929.805 meters
fo (revolution freq) 0.3224 0.3224 MHz
Harmonic No. 1560 2*3*4*5*13
α1 , α2 , α1/ α2 3.32*10-4 -1.82*10-4 -1.81
Uo (Dipole) 234.5 486.2 KeV
Uo (Dip.+1.8T) 1231.2 1921.8 KeV
εcrit1.96 3.287 KeV
εx (bare) 1.66 2.39 nm
εx (54m 1.8T) 0.47 0.687 nm
δe bare (+1.8T) 0.046 (0.10) 0.0558 (0.12) %
Lb (bare, 3%RF) 2.7 (9) 3.11 (10.34) mm (psec)
x,y,e (bare) 79.5,79.4, 39.7 46, 45.9, 23 msec
(Qx, Qx) =
(34.38, 20.68) (ξx, ξx) = (-104.4, -36.2)
βx, βy (6m ID) = 6.2, 1.42 βx, βy (15m ID) = 15.1, 16.2
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NSLS-II Lattice SummaryNSLS-II Lattice Summary
DBA-32 lattice has advantage of dispersion region optimized to reduce sextupole strengths and nonlinear driving terms
Extra ID’s used for damping wigglers to lower emittance and control user changes of the emittance from changing gaps
Damping wigglers provide high flux, brilliance beams for users missing from dipoles, dipole beam great VUV sources
Dynamic aperture with tolerances, first look appears achievable
Quadruplet in ID’s essential for control of linear optics from undulators