NSLSII Lattice Design S Kramer J Bengtsson S
NSLS-II Lattice Design S. Kramer, J. Bengtsson, S. Krinsky, T. Shaftan, D. Wang, L. Yun, I. Pinayev May 11, 2006 1. 2. TBA-24 Lattice Design - Advantages and shortcomings 1. Low emittance -> high chromaticity -> small DA from nonlinear dynam. 2. TBA dispersion region major limitation for reducing sextupole strength DBA-32 Lattice Design - Damping Wigglers for Emittance Control Linear design with working point for non-linear DA optimization ID’s e. Xtra long (15 m) and standard Length (6 m) 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) 1 BROOKHAVEN SCIENCE
TBA-24 Lattice Design worked on for ~2 years Reached 1. 5 nm emittance in 630 m but DA small, 2. 2 nm 758 m 2 BROOKHAVEN SCIENCE
TBA-24 Lattice Features TBA-24 Lattice very flexible Lower emittance period than DBA, 24 period εx >0. 38 nm Tune variable over big range for constant emittance α 1 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 3 BROOKHAVEN SCIENCE
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 4 BROOKHAVEN SCIENCE
Basic DBA-32 Cell 6 m ID Qx= 1. 09 (1. 13), ξx = -3. 38 (-3. 6) εx =1. 66 (1. 74)nm Qy= 0. 72 (0. 35), ξy = -1. 25 (-1. 01) C= 868 (845)m +35. 2 m in dipoles 5 (ESRF@3 Ge. V) BROOKHAVEN SCIENCE
Two Types of ID with SP=8 ID’s = 15 m +3* 6 m C=929. 8 m εx =1. 66 nm ξx, y = -3. 26, -1. 13/per 6 BROOKHAVEN SCIENCE
Emittance vs Damping Wiggler B-field Lw = 54 m ρw = 1. 4*Bρ/Bw Energy Spread vs Wiggler Field Emittance change vs Wiggler Field Bdipole=0. 66 T Bdipole=0. 33 T 7 BROOKHAVEN SCIENCE
Damping Wigglers in 4 -15 m ID Power radiated could exceed 125 KW in one 15 ID, canting will reduce threat to front end components and yield 3 or more user beams 8 BROOKHAVEN SCIENCE
DBA 32 Working Point SP=8 Tune selected from DA scan and optimized for reduced Closed Orbit Amplification 9 BROOKHAVEN SCIENCE
Closed Orbit Amplification Factors Quadrupole alignment tolerance reduced by small Beta functions and tune 10 BROOKHAVEN SCIENCE
DBA 32 Tune Scan for Cell At each tune value: driving terms were optimized to 3 rd order and DA area calculated yields peak near (4. 29, 2. 615) 11 BROOKHAVEN SCIENCE
DA for Tune and 11 Sext. Families Frequency map shows diffusion at high order resonances and tune shifts 12 BROOKHAVEN SCIENCE
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 13 BROOKHAVEN SCIENCE
Adding Synchrotron Oscillations DA maintains reasonable values but momentum aperture more symmetric For random alignment tolerances < 100 μm with correction injection okay 14 BROOKHAVEN SCIENCE
NSLS-II Lattice Parameters Energy 3 3. 6 Ge. V Io (Total Current) 0. 500 0. 241 Amps Circumference 929. 805 meters fo (revolution freq) 0. 3224 MHz Harmonic No. 1560 2*3*4*5*13 α 1 , α 2 , α 1/ α 2 3. 32*10 -4 -1. 81 Uo (Dipole) 234. 5 486. 2 Ke. V Uo (Dip. +1. 8 T) 1231. 2 1921. 8 Ke. V εcrit 1. 96 3. 287 Ke. V εx (bare) 1. 66 2. 39 nm εx (54 m 1. 8 T) 0. 47 0. 687 nm δe bare (+1. 8 T) 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) = βx, βy (6 m ID) = (ξx, ξx) = (34. 38, 20. 68) βx, βy (15 m ID) = 6. 2, 1. 42 15 (-104. 4, -36. 2) 15. 1, 16. 2 BROOKHAVEN SCIENCE
NSLS-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 16 BROOKHAVEN SCIENCE
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