Matching section layout vs crab cavity voltage
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Matching section layout vs. crab-cavity voltage. Barbara Dalena A. Chancé , J. Payet R. De Maria, S. Fartoukh. Contents. introduction and motivation reduction of crab voltage new IR1/5 Matching S ection (MS) layout (except Inner Triplet (IT), see R. De M aria’s talk)

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Matching section layout vs crab cavity voltage

Matching section layout vs. crab-cavity voltage

Barbara Dalena

A. Chancé, J. Payet

R. De Maria, S. Fartoukh


Contents

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


Matching section layout vs crab cavity voltage

INTRODUCTION

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


Crab cavity voltage

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


Optimization desiderata

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


New matching section layout

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


Matching section layout vs crab cavity voltage

INJECTION

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


Injection optics

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


Injection apertures

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


Matching section layout vs crab cavity voltage

COLLISION

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


Pre squeeze optics

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


Squeeze optics

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


Squeeze apertures

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


Crab cavity voltage gain

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


Lattice squeeze ability

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


Apertures

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


Matching section layout vs crab cavity voltage

CHROMATICS PROPERTIES

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


Chromaticity correction

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


Geometric aberrations compensation

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


Conclusion outlook

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


Crab cavity voltage1

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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