squeeze optics and power converter settings

LHCCWG - November 29th 2006 1

Squeeze optics and power Squeeze optics and power converter settingsconverter settings

S. Fartoukh, M. Giovannozzi, J. Jowett, Y. Papaphilippou

Questions addressed:Questions addressed:

• Can we ramp at constant optics and crossing scheme?Can we ramp at constant optics and crossing scheme?

• Behaviour of optical parameters during squeeze of IR1 Behaviour of optical parameters during squeeze of IR1 and/or IR5and/or IR5

• Number of matched optics during squeezeNumber of matched optics during squeeze

• Status of squeeze optics for IR2 and 8Status of squeeze optics for IR2 and 8


IntroductionIntroduction

• The material concerning the squeeze for IR1 and 5 can be found at:– S. Fartoukh -> 23 LTC meeting, 31/03/04.

• The material concerning the crossing scheme for IR1 and 5 during the squeeze can be found at:– S. Fartoukh -> LOC meeting, 11/10/05.

• All the optics files are stored in the official database under V6.5


Can we ramp at constant optics and Can we ramp at constant optics and crossing scheme? - Icrossing scheme? - I

• IR1 and 5:– Optics: injection optics can be ramped up to 7

TeV– Crossing scheme:

• for beta* = 11 m, = 200 rad, par. sep. = 2 mm, MCBYs at Q4 (mainly for par. Sep.) are at 107% of nominal at 7 TeV -> the injection crossing scheme can be ramped (tight, but feasible).

• For beta* = 17 m , = 160 rad, par. sep. = 2.5 mm, the same correctors are at 132% of nominal at 7 TeV -> the injection crossing scheme has to be changed at about 5 TeV.


Can we ramp at constant optics and Can we ramp at constant optics and crossing scheme? - IIcrossing scheme? - II

• IR2 and 8:– Optics: injection optics can be ramped up to 7TeV.

Important point: strength of triplets is 220 T/m instead of 205 T/m (due to the injection contraints of phase advance between septum and kicker)!

– Crossing scheme:• IR2: the MCBY correctors in Q4 are limited in strength. In

principle the injection crossing scheme cannot be ramped up to 7TeV. This issue should be studied in more details to assess whether alternative solution is possible…

• IR8: no strength limitation is present, even though the strengh requirements for MCBYs at Q4 are tight (due to par. sep.). Injection crossing scheme can be ramped up to 7TeV.


Behaviour of optical parameters Behaviour of optical parameters during squeeze of IR1 and/or IR5during squeeze of IR1 and/or IR5 - I- I

• Status of squeeze optics:– 12 matched optics for various beta* are available.– Solutions provide smooth variation of the quadrupole

gradients during squeeze.– A crossing scheme is implemented for each of the

matched optics.– Criteria imposed on crossing scheme during squeeze:

• Parallel separation kept constant

• Scaling of the X-angles:

• Scaling law for the IP shift:

r

mcolinj

colcolcolyx **

**

*

**

, 1)(

colyxyxs )(mm5.0)( *,

*,

S. Fartoukh LOC meeting, 11/10/2005S. Fartoukh LOC meeting, 11/10/2005


Squeeze (3/4)

Quadrupole gradients [T/m] in the Dispersion Suppressor (Q7-Q10) as a function of : beam1 (left) beam2 (right)

Rather smooth except for 1 m << 2 m

S. Fartoukh, 23 LTC meetingS. Fartoukh, 23 LTC meeting


Squeeze (4/4)

Quadrupole gradient [T/m] in the trim quadrupoles (QTL11,-QT12,QT13) as a function of : beam1 (left) beam2 (right)

Smooth/monotonous for beam1 but more “erratic’’ for beam2, with unavoidable zero-crossing for both beams (matching procedure could be optimised if needed)

S. Fartoukh, 23 LTC meetingS. Fartoukh, 23 LTC meeting


Behaviour of optical parameters during Behaviour of optical parameters during squeeze of IR1 and/or IR5squeeze of IR1 and/or IR5 - III- III

S. Fartoukh LOC meeting, 11/10/2005S. Fartoukh LOC meeting, 11/10/2005


Behaviour of optical parameters during Behaviour of optical parameters during squeeze of IR1 and/or IR5squeeze of IR1 and/or IR5 - IV- IV

• Simulation conditions:– Plain V6.5 layout with nominal optics.– No errors (alignment or magnetic) included.– The 12 matched optics are used (collision tunes –

0.31/0.32, and chromaticities set to 2 with SF/SD circuits).

– In between two matched optics the gradients are obtained by linear interpolation.

– For intermediate optics relevant beam parameters are evaluated.


Behaviour of optical parameters during Behaviour of optical parameters during squeeze of IR1 - Isqueeze of IR1 - I

-2.0E-03

-1.5E-03

-1.0E-03

-5.0E-04

0.0E+00

0.0 1.0 2.0 3.0 4.0 5.0 6.0 7.0 8.0 9.0 10.0 11.0 12.0

Horizontal beta* (m)

Del

ta t

un

e

9.990E-03

1.009E-02

1.019E-02

1.029E-02

1.039E-02

1.049E-02

Tu

ne

split

DQ Hor. (Beam 1)

DQ Ver. (Beam 1)

Tune split


Behaviour of optical parameters during Behaviour of optical parameters during squeeze of IR1 - IIsqueeze of IR1 - II

2.0

2.1

2.2

0.0 1.0 2.0 3.0 4.0 5.0 6.0 7.0 8.0 9.0 10.0 11.0 12.0


Ch

rom

atic

ity

Chrom. Hor. (Beam 1) Chrom. Ver. (Beam 1)


Behaviour of optical parameters during Behaviour of optical parameters during squeeze of IR1 - IIIsqueeze of IR1 - III

-5.5E-03

-4.5E-03

-3.5E-03

-2.5E-03

-1.5E-03

-5.0E-04

5.0E-04

1.5E-03

2.5E-03

0.0 1.0 2.0 3.0 4.0 5.0 6.0 7.0 8.0 9.0 10.0 11.0 12.0


Del

ta t

un

e

9.00E-03

1.40E-02

1.90E-02

2.40E-02

2.90E-02

Tu

ne

split

DQ Hor. (Beam 2)DQ Ver. (Beam 2)Tune split

Beam 2 seems to be more Beam 2 seems to be more critical than critical than Beam 1Beam 1! ! However, no problem down However, no problem down to beta* = 2m.to beta* = 2m.

Critical region for Critical region for Beam 2Beam 2: smoothing : smoothing should improve itshould improve it


Behaviour of optical parameters during Behaviour of optical parameters during squeeze of IR1 - IVsqueeze of IR1 - IV

1.4

1.5

1.6

1.7

1.8

1.9

2.0

2.1

2.2

0.0 1.0 2.0 3.0 4.0 5.0 6.0 7.0 8.0 9.0 10.0 11.0 12.0


Ch

rom

atic

ity


Beam 2 seems to be more Beam 2 seems to be more critical than critical than Beam 1Beam 1! ! However, no problem down However, no problem down to beta* = 2m.to beta* = 2m.



Behaviour of optical parameters during Behaviour of optical parameters during squeeze of IR1 - Vsqueeze of IR1 - V

-1.0

-0.5

0.0

0.5

1.0

0.0 1.0 2.0 3.0 4.0 5.0 6.0 7.0 8.0 9.0 10.0 11.0 12.0


Bet

a b

eati

ng

(%

)

Hor. Plane (Beam 1)Ver. Plane (Beam 1)

Computed outside IR1/5Computed outside IR1/5


Behaviour of optical parameters during Behaviour of optical parameters during squeeze of IR1 - VIsqueeze of IR1 - VI

-0.10

-0.05

0.00

0.05

0.10

0.0 1.0 2.0 3.0 4.0 5.0 6.0 7.0 8.0 9.0 10.0 11.0 12.0


Clo

sed

orb

it (

sig

ma)




Behaviour of optical parameters during Behaviour of optical parameters during squeeze of IR1 - VIIsqueeze of IR1 - VII

-10.0

-5.0

0.0

5.0

10.0

0.0 1.0 2.0 3.0 4.0 5.0 6.0 7.0 8.0 9.0 10.0 11.0 12.0


Bet

a b

eati

ng

(%

)


Computed outside IR1/5Computed outside IR1/5Critical region for Critical region for Beam 2Beam 2: smoothing : smoothing should improve itshould improve it


Behaviour of optical parameters during Behaviour of optical parameters during squeeze of IR1 - VIIIsqueeze of IR1 - VIII

-0.10

-0.05

0.00

0.05

0.10

0.0 1.0 2.0 3.0 4.0 5.0 6.0 7.0 8.0 9.0 10.0 11.0 12.0


Clo

sed

orb

it (

sig

ma)

Hor. Plane (Beam 2) Ver. Plane (Beam 2)




-0.0006

-0.0004

-0.0002

0.0000

0.0002

0.0004

0.0006

0.0 1.0 2.0 3.0 4.0 5.0 6.0 7.0 8.0 9.0 10.0 11.0 12.0


Po

siti

on

(m

)

-1.5E-04

-1.0E-04

-5.0E-05

0.0E+00

5.0E-05

1.0E-04

1.5E-04

Ver

. cro

ssin

g a

ng

le (

rad

)

Beam 1 - Hor. Pos. Beam 2 - Hor. Pos.

Beam 1 - Ver. Pos. Beam 2 - Ver. Pos.

Beam 1 - Ver. Crossing angle Beam 2 - Ver. Crossing angle

Behaviour of optical parameters during Behaviour of optical parameters during squeeze of IR1 - IXsqueeze of IR1 - IX

No impact of the squeeze on the No impact of the squeeze on the beam parameters at IP.beam parameters at IP.

7TeV crossing parameters. 7TeV crossing parameters. Matching with injection Matching with injection crossing to be discussed.crossing to be discussed.


Number of matched optics during Number of matched optics during squeezesqueeze - I- I

• Two test cases considered:– Removal of two matched optics (beta* = 4 m and 2.5

m).• Beta* = 4 m: whenever removed the optical parameters

remain bounded, e.g., tune variation below 1E-3.• Beta* = 2.5 m: whenever removed the optical parameters

grow, e.g., tune variation above 4E-3.

– Academic case: remove successive points below 11 m to determine behaviour of optical parameters.


Number of matched optics during Number of matched optics during squeezesqueeze - II- II

-5.0E-03

-4.5E-03

-4.0E-03

-3.5E-03

-3.0E-03

-2.5E-03

-2.0E-03

-1.5E-03

-1.0E-03

-5.0E-04

0.0E+00

0.0 1.0 2.0 3.0 4.0 5.0 6.0 7.0 8.0 9.0 10.0 11.0 12.0


De

lta

tun

e

9.990E-03

1.004E-02

1.009E-02

1.014E-02

1.019E-02

Tu

ne

sp

lit

DQ Hor. (Beam 1) - nom.

DQ Ver. (Beam 1) - nom.

DQ Hor. (Beam 1)DQ Ver. (Beam 1)

Tune split - nom.

Tune split


Number of matched optics during Number of matched optics during squeezesqueeze - III- III

-3.0E-02

-2.5E-02

-2.0E-02

-1.5E-02

-1.0E-02

-5.0E-03

0.0E+00

0.0 1.0 2.0 3.0 4.0 5.0 6.0 7.0 8.0 9.0 10.0 11.0 12.0


Del

ta t

un

e

9.80E-03

9.90E-03

1.00E-02

1.01E-02

1.02E-02

1.03E-02

1.04E-02

1.05E-02

Tu

ne

split

DQ Hor. (Beam 1)

DQ Ver. (Beam 1)

Tune split


Number of matched optics during Number of matched optics during squeezesqueeze - IV- IV

2.0

2.5

3.0

3.5

4.0

4.5

5.0

5.5

6.0

0.0 1.0 2.0 3.0 4.0 5.0 6.0 7.0 8.0 9.0 10.0 11.0 12.0


Ch

rom

atic

ity



Behaviour of optical parameters during Behaviour of optical parameters during squeeze of IR5squeeze of IR5

• Whenever IR5 is squeezed the results are very much the same as for IR1 (taking into account the exchange of the crossing plane): no particular new issue observed.


Behaviour of optical parameters during Behaviour of optical parameters during combined squeeze of IR1 and 5 - Icombined squeeze of IR1 and 5 - I

• Larger variations of the optical parameters are observed. In particular:– Horizontal and vertical planes have equal behaviour for

closed orbit leakage < 0.1 .– Beam 1:

• Factor 2 larger tune variations -> Q ~ 3E-3• Chromaticities almost unaffected -> Q’ ~ 0.15• Factor 1.5 in beta-beating -> / ~ 1.5%• Orbit leakage almost unaffected < 0.1

– Beam 2 (similar values as of Beam 1, except for 1 m <beta* < 2 m):• Factor 2 larger tune variations -> Q ~ 6E-3 • Chromaticities strongly affected -> Q’ ~ 2• Factor 1.5 in beta-beating -> / ~ 10-15%• Orbit leakage almost unaffected < 0.1


Behaviour of optical parameters during Behaviour of optical parameters during combined squeeze of IR1 and 5 - IIcombined squeeze of IR1 and 5 - II

-7.0E-03

-5.0E-03

-3.0E-03

-1.0E-03

1.0E-03

3.0E-03

5.0E-03

0.0 1.0 2.0 3.0 4.0 5.0 6.0 7.0 8.0 9.0 10.0 11.0 12.0


Del

ta t

un

e

8.00E-03

1.30E-02

1.80E-02

2.30E-02

2.80E-02

Tu

ne

split

DQ Hor. (Beam 2)DQ Ver. (Beam 2)Tune split



Behaviour of optical parameters during Behaviour of optical parameters during combined squeeze of IR1 and 5 - IIIcombined squeeze of IR1 and 5 - III

0.00.10.20.30.40.50.60.70.80.91.01.11.21.31.41.51.61.71.81.92.02.12.2

0.0 1.0 2.0 3.0 4.0 5.0 6.0 7.0 8.0 9.0 10.0 11.0 12.0


Ch

rom

atic

ity




Status of squeeze optics for IR2 Status of squeeze optics for IR2 and 8and 8

• As far as the other insertions are concerned:– IR8:

• it is foreseen to be squeezed down to beta* = 2 m (1 m is excluded due to aperture issues).

• Optics files present, but not optimized, yet (quadrupoles variation not smooth enough). Once the optical solutions will be in final form, the approach presented should be repeated. The crossing scheme needs also to be implemented during the squeeze.

– IR2: • it is foreseen to be un-squeezed for protons and squeezed down to

beta* = 0.5 m for ions. • Optics files for the un-squeeze are still missing, while those for the

ions are available. In both cases the crossing scheme needs to be computed.

– IR2 and 8: transition from beta* = 10 m and MQX strength from 220 T/m to 205 T/m.


Summary and outlookSummary and outlook• MADX tool developed to qualify the squeeze.• Ramping with constant optics (injection) up to 7TeV is feasible (for

IR2 and 8 it will depend on performance of triplet quadrupoles).• Ramping with constant crossing scheme (injection) up to 7TeV is

problematic for IR2 (to be re-computed) and thigh, but feasible for IR1, 5, and 8.

• Strength issues will not impose the choice of when to change optics/crossing scheme.

• Squeeze with one insertion at a time (IR1 or 5) is not an issue in terms of optical parameters (and for a perfect machine). – Impact of errors to be assessed.– Behaviour of Beam 2 to be analyzed in details (possibly fixed by

smoothing transition between beta* 1 m and 2 m).• Squeeze with both insertions at a time (IR1 and 5) is feasible,

provided situation of Beam 2 is fixed.• Optics squeeze of other insertions (IR2 and 8) to be

computed/finalized. Their contribution should be assessed.• Transition from injection to collision crossing scheme to be

studied.

squeeze optics and power converter settings

Documents

injection optics

injection crossing scheme

nominal optics

constant optics

optics files

tevcrossing scheme

fartoukh loc meeting

fartoukh loc meeting