Matching section layout vs. crab-cavity voltage

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

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


4

Crab cavity voltage


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

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


New matching section layoutD2 CRAB Q4 Q5 Q6 Q7

D2 CRAB Q4 Q5 Q6 Q7

new

Q7+

22.1 m 22.1 m

7

INJECTION


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

9

Injection apertures


* = 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

10

COLLISION


11

Pre-squeeze optics


• 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

12

Squeeze optics


• possibility to build squeeze optics with the ATS scheme at * =20, 15 cm

• some sextupoles run at maximum current

*= 15cm

13

Squeeze apertures


• 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


14

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


possibility to reduce the crab voltage of about 30-40%


Lattice squeeze-ability

• possibility to build squeeze optics in non ATS mode at * 13 cm

• chromaticity correction strategy not known yet

* = 14 cm


apertures

• no aperture problems for the Matching Section magnets


* = 14 cm

17

CHROMATICS PROPERTIES


18

Chromaticity correction


• 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

19

Geometric aberrations compensation


• 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

20

Conclusion & Outlook


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

22

Crab cavity voltage• reduce the voltage of the crab cavity: V 1/(*)1/2

by increasing the beta functions in Q4

IT MS-ARC


Matching section layout vs. crab-cavity voltage

Documents

Transcript of Matching section layout vs. crab-cavity voltage