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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) - PowerPoint PPT Presentation
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The HiLumi LHC Design Study is included in the High Luminosity LHC project and is partly funded by the European Commission within the Framework Programme 7 Capacities Specific Programme, Grant Agreement 284404.
Matching section layout vs. crab-cavity voltage
Barbara Dalena
A. Chancé, J. Payet
R. De Maria, S. Fartoukh
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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
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INTRODUCTION
2nd joint HiLumi LHC-LARP Annual Meeting, 15 November 2012 Frascati
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Crab cavity voltage
2nd joint HiLumi LHC-LARP Annual Meeting, 15 November 2012 Frascati
D2 CRAB Q4 Q5 Q6 Q7
LHC HL-LHC baseline
Q4MQY, G=160 T/m @4.5 K = 70 mm, L = 3.4 m
MQYY, G=120 T/m @1.9 K = 90 mm, L = 3.5 m
Q5MQML, G=160 T/m @4.5 K = 56 mm, L = 4.8 m
MQYL, G=160 T/m @4.5 K = 70 mm, L = 4.8 m
Q6MQML, G=160 T/m @4.5 K = 56 mm, L = 4.8 m
MQML, G=160 T/m @4.5 K = 56 mm, L = 4.8 m
Q72MQM, G=200 T/m @1.9 K = 56 mm, L = 3.4 m
2MQM, G=200 T/m @1.9 K= 56 mm, L = 3.4 m
Þ increasing the beta function at the CRAB
using • MS quadrupole types • MS quadrupole
positions
Reduce the voltage of the crab cavity: V 1/(*)1/2
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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
2nd joint HiLumi LHC-LARP Annual Meeting, 15 November 2012 Frascati
Optics used for this study is the option with the triplet gradient of 170 T/m
62nd joint HiLumi LHC-LARP Annual Meeting, 15 November 2012 Frascati
New matching section layoutD2 CRAB Q4 Q5 Q6 Q7
D2 CRAB Q4 Q5 Q6 Q7
new
Q7+
22.1 m 22.1 m
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INJECTION
2nd joint HiLumi LHC-LARP Annual Meeting, 15 November 2012 Frascati
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Injection optics
2nd joint HiLumi LHC-LARP Annual Meeting, 15 November 2012 Frascati
• 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
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Injection apertures
2nd joint HiLumi LHC-LARP Annual Meeting, 15 November 2012 Frascati
* = 2.5 m
• aperture problem in Q6 Þ 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
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COLLISION
2nd joint HiLumi LHC-LARP Annual Meeting, 15 November 2012 Frascati
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Pre-squeeze optics
2nd joint HiLumi LHC-LARP Annual Meeting, 15 November 2012 Frascati
• 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
HL-LHC baseline new layout
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Squeeze optics
2nd joint HiLumi LHC-LARP Annual Meeting, 15 November 2012 Frascati
• possibility to build squeeze optics with the ATS scheme at * =20, 15 cm
• some sextupoles run at maximum current
*= 15cm
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Squeeze apertures
2nd joint HiLumi LHC-LARP Annual Meeting, 15 November 2012 Frascati
• no major aperture problems up to *=15 cm in the Matching Section magnets
• Q5 aperture closer to the n1=7 limit than the other magnets Þ can be improved by re-orienting the beam screen
• apertures in the triplet are scaled to 150 mm
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Crab-cavity voltage gain
CRAB side and beamHL-LHC baseline [MV]
Best optimization [MV]
Horizontal L5 Beam 1 11.8 8.0
Horizontal R5 Beam 1 13.4 8.2
Horizontal L5 Beam 2 13.4 8.2
Horizontal R5 Beam 2 11.8 8.0
Vertical L1 Beam 1 13.1 8.1
Vertical R1 Beam 1 11.9 8.0
Vertical L1 Beam 2 11.9 8.0
Vertical R1 Beam 2 13.1 8.1
2nd joint HiLumi LHC-LARP Annual Meeting, 15 November 2012 Frascati
possibility to reduce the crab voltage of about 30-40%
152nd joint HiLumi LHC-LARP Annual Meeting, 15 November 2012 Frascati
Lattice squeeze-ability
• possibility to build squeeze optics in non ATS mode at * 13 cm
• chromaticity correction strategy not known yet
* = 14 cm
162nd joint HiLumi LHC-LARP Annual Meeting, 15 November 2012 Frascati
apertures
• no aperture problems for the Matching Section magnets
• apertures in the triplet are scaled to 150 mm
* = 14 cm
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CHROMATICS PROPERTIES
2nd joint HiLumi LHC-LARP Annual Meeting, 15 November 2012 Frascati
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Chromaticity correction
2nd joint HiLumi LHC-LARP Annual Meeting, 15 November 2012 Frascati
• the ATS scheme gives good chromaticity correction in the horizontal plane
• the relative tune variation (fractional part) changes from 1% to 2% in the vertical plane
* = 15 cm
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Geometric aberrations compensation
2nd joint HiLumi LHC-LARP Annual Meeting, 15 November 2012 Frascati
• stop band width of the 3Qx resonance is increased• new ninth order coupling resonances are excited
Detuning with amplitude (IP1, * = 15 cm)
3Qx = 187 3Qx-6Qy = 175 3Qx+6Qy = 5494Qy-Qx = 179
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Conclusion & Outlook
2nd joint HiLumi LHC-LARP Annual Meeting, 15 November 2012 Frascati
LHC HiLumi baseline Proposed layout
Q4MQY, G=160 T/m @4.5 K = 70 mm, L = 3.4 m
MQYY, G=120 T/m @1.9 K = 90 mm, L = 4.5 m
MQYY, G=120 T/m @1.9 K = 90 mm, L = 3.5 m
Q5MQML, G=160 T/m @4.5 K = 56 mm, L = 4.8 m
MQYL, G=160 T/m @4.5 K = 70 mm, L = 4.8 m
MQYL, G=160 T/m @4.5 K = 70 mm, L = 4.8 m
Q6MQML, G=160 T/m @4.5 K = 56 mm, L = 4.8 m
MQML, G=160 T/m @4.5 K = 56 mm, L = 4.8 m
MQYL, G=160 T/m @4.5 K = 70 mm, L = 4.8 m
Q72MQM, G=200 T/m @1.9K = 56 mm, L = 3.4 m
2MQM, G=200 T/m @1.9 K= 56 mm, L = 3.4 m
2MQM, G=200 T/m @1.9 K= 56 mm, L = 3.4 m
Q7+2MQM, G=160 T/m @4.5 K= 56 mm, L = 3.4 m
• possibility to reduce crab cavity voltage by 30-40%• possibility to gain some lattice flexibility in collision and injection Þ chromatic correction needs to be tunedÞ work out solutions for injection optics at * 4 mÞ integrate the proposed solution with the new Inner Triplet
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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