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Matching section layout vs. crab-cavity voltage

This presentation discusses the reduction of crab cavity voltage by 30-40% through an optimized matching section layout for the High-Luminosity Large Hadron Collider (HL-LHC). Key topics include the new Matching Section layout's properties, injection optics, squeeze-ability, and chromatic properties. The focus is on increasing beta functions at the crab cavity location and ensuring compatibility with injection optics. The findings aim to enhance lattice flexibility and improve chromatic correction while addressing potential challenges in injection optics with higher beta values.

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Matching section layout vs. crab-cavity voltage

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  1. Matching section layout vs. crab-cavity voltage Barbara Dalena A. Chancé, J. Payet R. De Maria, S. Fartoukh

  2. Contents • introduction and motivation • reduction of crab voltage • new IR1/5 Matching Section (MS) layout (except Inner Triplet (IT), see R. De Maria’s talk) • properties of the new layout • injection optics • squeeze-ability • chromatics properties 2nd joint HiLumi LHC-LARP Annual Meeting, 15 November 2012 Frascati

  3. INTRODUCTION 2nd joint HiLumi LHC-LARP Annual Meeting, 15 November 2012 Frascati

  4. Crab cavity voltage Reduce the voltage of the crab cavity: V  1/(*)1/2 D2 CRAB Q4 Q5 Q6 Q7 • increasing the beta • functionat the CRAB • using • MS quadrupole types • MS quadrupole positions 2nd joint HiLumi LHC-LARP Annual Meeting, 15 November 2012 Frascati

  5. Optimization desiderata Higher  function at crab cavity location Compatible with injection optics (at * as low as possible) pre-squeeze within and possibly beyond the chromatic limits squeezable to very low * to back-up ATS Optics used for this study is the option with the triplet gradient of 170 T/m 2nd joint HiLumi LHC-LARP Annual Meeting, 15 November 2012 Frascati

  6. New matching section layout D2 CRAB Q4 Q5 Q6 Q7 Q7+ D2 CRAB Q4 Q5 Q6 Q7 22.1 m 22.1 m new 2nd joint HiLumi LHC-LARP Annual Meeting, 15 November 2012 Frascati

  7. INJECTION 2nd joint HiLumi LHC-LARP Annual Meeting, 15 November 2012 Frascati

  8. Injection optics • possibility to build injection • optics with * of 2.0-3.0 m • w and w/o ATS R/L phases • difficult to build injection • optics with *  4.0 m, • because the added • quadrupole Q7+ becomes • too weak * = 2.5 m 2nd joint HiLumi LHC-LARP Annual Meeting, 15 November 2012 Frascati

  9. Injection apertures • aperture problem in Q6 •  can be cured by changing • the MQML in MQYL type • apertures of the additional • Q7 magnet not modeled but • should be the same as Q7, • due to same  constraints • apertures in the triplet are • scaled to 150 mm * = 2.5 m 2nd joint HiLumi LHC-LARP Annual Meeting, 15 November 2012 Frascati

  10. COLLISION 2nd joint HiLumi LHC-LARP Annual Meeting, 15 November 2012 Frascati

  11. Pre-squeeze optics new layout HL-LHC baseline • optimum values of beta’s at crab cavity can be found by optimizing the distance of • the outer triplet quadrupoles Q4/Q5/Q6, and optimizing the strength of the new Q7 2nd joint HiLumi LHC-LARP Annual Meeting, 15 November 2012 Frascati

  12. Squeeze optics • possibility to build squeeze • optics with the ATS scheme at • * =20, 15 cm • some sextupoles run at • maximum current *= 15cm 2nd joint HiLumi LHC-LARP Annual Meeting, 15 November 2012 Frascati

  13. Squeeze apertures • no major aperture problems • up to *=15 cm in the • MatchingSection magnets • Q5 aperture closer to the n1=7 • limit than the other magnets •  can be improved by • re-orienting the beam screen • apertures in the triplet are • scaled to 150 mm 2nd joint HiLumi LHC-LARP Annual Meeting, 15 November 2012 Frascati

  14. Crab-cavity voltage gain possibility to reduce the crab voltage of about 30-40% 2nd joint HiLumi LHC-LARP Annual Meeting, 15 November 2012 Frascati

  15. Lattice squeeze-ability • possibility to build squeeze • optics in non ATS mode • at *  13 cm • chromaticity correction • strategy not known yet * = 14 cm 2nd joint HiLumi LHC-LARP Annual Meeting, 15 November 2012 Frascati

  16. apertures • no aperture problems for the • Matching Section magnets • apertures in the triplet are • scaled to 150 mm * = 14 cm 2nd joint HiLumi LHC-LARP Annual Meeting, 15 November 2012 Frascati

  17. CHROMATICS PROPERTIES 2nd joint HiLumi LHC-LARP Annual Meeting, 15 November 2012 Frascati

  18. Chromaticity correction • the ATS scheme gives good • chromaticity correction • in the horizontal plane * = 15 cm • the relative tune variation • (fractional part) changes from 1% • to 2% in the vertical plane 2nd joint HiLumi LHC-LARP Annual Meeting, 15 November 2012 Frascati

  19. Geometric aberrations compensation Detuning with amplitude (IP1, * = 15 cm) 3Qx = 187 4Qy-Qx = 179 3Qx-6Qy = 175 3Qx+6Qy = 549 • stop band width of the 3Qx resonance is increased • new ninth order coupling resonances are excited 2nd joint HiLumi LHC-LARP Annual Meeting, 15 November 2012 Frascati

  20. Conclusion & Outlook • possibility to reduce crab cavity voltageby 30-40% • possibility to gain some lattice flexibility in collision and injection •  chromatic correction needs to be tuned • work out solutions for injection optics at *  4 m • integrate the proposed solution with the new Inner Triplet 2nd joint HiLumi LHC-LARP Annual Meeting, 15 November 2012 Frascati

  21. Crab cavity voltage • reduce the voltage of the crab cavity: V  1/(*)1/2 by increasing the beta functions in Q4 IT MS-ARC 2nd joint HiLumi LHC-LARP Annual Meeting, 15 November 2012 Frascati

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