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Final Focus optics for Possible New B-Line

This study discusses the development of new optics for the B-Line system, focusing on sub-picosecond bunch compression and final focus adjustments. The proposed system aims to enhance beam compression efficiency and optimize the final focus for improved performance. The design includes local chromaticity correction and shorter L* for compactness, while adhering to specific constraints for compatibility with short bunch operations. Performance evaluations show promising results for both SPPS and LCLS beams. Further optimizations to reduce aberrations for the SPPS beam and potential changes in the optics design are suggested for enhanced performance. The study also addresses considerations such as space allocation for undulators, shield wall relocation, magnet standardization, and angle adjustments for optimal tunnel fit. Overall, the proposed new B-Line system offers the potential for significant improvements in beam compression and focus adjustment capabilities.

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Final Focus optics for Possible New B-Line

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  1. Final Focus optics for Possible New B-Line A. Seryi, P. Emma, R. Erickson, T. Fieguth, M. Hogan, et al. 4 October 2004 NLC BDS meeting

  2. spps g Sub-picosecond bunchcompression Final Focus and beam dump FF IP

  3. Shielding wall Shielding wall

  4. 50-line B-line sec-30 Q30 B1 FF-system starts here B2 sext. e-meas. Q31 MAD optics outputplot Notes on Possible New B-Line Slide from P. Emma, R. Erickson, T. Fieguth, M. Hogan, A. Seryi, et al. Sep. 29, 2004

  5. Dyx,y= 120 -I energy centroid and spread meas. 3 wire-scanner e-meas. section Notes on Possible New B-Line Slide from P. Emma, R. Erickson, T. Fieguth, M. Hogan, A. Seryi, et al. Sep. 29, 2004

  6. Longitudinal tracking through B-line, but prior to FF-system (SPPS mode at 28.5 GeV) R56 = -2.3 mm T566 = -35 mm Notes on Possible New B-Line Slide from P. Emma, R. Erickson, T. Fieguth, M. Hogan, A. Seryi, et al. Sep. 29, 2004

  7. Possible New B-line Parameters (SPPS-B) Notes on Possible New B-Line Slide from P. Emma, R. Erickson, T. Fieguth, M. Hogan, A. Seryi, et al. Sep. 29, 2004

  8. Final Focus Energy Collimation Betatron Collimation NLC NLC Beam Delivery System Final focus with local chromaticity correction

  9. New B-Line Final Focus • Same design concept as NLC FF (also adopted for ILC FF) • Local chromaticity correction in FD • Shorter L*, to be compact, but same chromaticity as in ILC • B-Line FF: L*=1m, bY*=0.1mm • ILC FF: L*=4m, bY*=0.4mm • Additional constraints to be compatible with short bunch operation • Limit R56 and T566 terms • The tentative optics shown below is designed with these constraints • The optics is tentative (ver.10), and is being improved

  10. New B-Line with sub picosecond bunch compression New Final Focus

  11. New FF for B-Line, version SHRTFF10.mad L*=1m, and IP bx=4mm, by=0.1mm (same chromaticity as present ILC parameters)

  12. Final Doublet of New FF for B-Line, with sextupoles for local chromaticity correction, optics version SHRTFF10.mad

  13. Survey of New B-Line with FF Optics till FF is in blue, FF optics is in red z=0 at the end of BLINE0

  14. Survey of New B-Line with FF FF shown in red, dashed line show straight line from FF entrance

  15. with B-Line Evolution of FF optics performance versus version number Beam size shown is obtained with Turtle tracking Versions 8,9,10 include New B-Line bunch compression system

  16. Performance of B-Line+FF optics version 10 Beam size shown is obtained with Turtle tracking Already rather good for LCLS beam, can be further improved for SPPS beam

  17. New B-Line + FF short bunch performance • Complete system (B-Line + FF ver.10): • R56= -2.29 mm, T566= -77.18 mm • For beamline up to beginning of FF: • R56= -2.185 mm, T566= -31.29 mm • => FF does not change R56 but ~ doubles T566 • => With SPPS beam (sE~1.5%), bunch length at IP will be lengthened by about 17mm which is still smaller than the SPPS beam goal of sz= 50mm

  18. New B-Line + FF tracking cross-checks and Synchrotron Radiation • Tracking of the full system (B-Line + FF ver.10) with Turtle and with Dimad agree to better than 5% in terms of the IP beam size • Effects of SR (tracking by Dimad) on IP size increase: • LCLS beam: Dsx~2.8% , Dsy~0.8% • SPPS beam: Dsx~6% , Dsy~14% • => SR effects are reasonably small

  19. B-line +FF Parameters and Performance

  20. Tracked beam at IP of FF for SPPS and LCLS beam parameters on the same scale IP beam size of the tracked (SR included) beam in a complete B-Line +FF system : LCLS parameters: sx / y = 0.44 / 0.070 mm SPPS parameters: sx / y = 4.5 / 0.160 mm Further optimization of FF optics may allow further reduction of the IP beam size in SPPS case LCLS beam, zoom in

  21. Changes needed in FF optics ver.10 • Provide space (3m?) for undulators in the beginning of FF • will lead to some lengthening of the system • Take into account present shield wall • Will shift FF about 7m downstream, if the wall is kept • Can the shield wall be removed or relocated? • Lengthen Final Doublet quads QF1 and QD0 about twice (for 30 GeV beam) • will lead to minor lengthening of overall beamline • Determine length needed for beam dump, if there is space left, use it for FF or undulators • Continue optimization, possibly, further reduce aberrations for SPPS beam • Standardize magnets, possibly use existing • Adjust angles in B-Line to fit to tunnel optimally • Look for ways to reduce T566

  22. Survey of New B-Line with FF z=0 at the end of BLINE0 If the shield wall remains, need to lengthenbeginning of FF (will also help to create space for undulators) Note that the top plot is versus z and bottom versus s which are 1-1.5m different => location correspondence is approximate

  23. Summary • New B-Line with sub-picosecond bunch compressor and with compact final focus may have the following capabilities in terms of the IP beam size: • sx,y,z~ 4.5 * 0.16 * 50 mm for 30 GeV SPPS beam • sx,y,z~ 0.45 * 0.07 * 20 mm for 14 GeV LCLS beam

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