EXT Beam Measurements & Corrections

M. Woodley

EXT Beam Measurements & Corrections

Dispersion, Coupling, Beta Matching

10th ATF2 Project Meeting, June 30 2010 1/31

M. Woodley10th ATF2 Project Meeting, June 30 2010

-100 -80 -60 -40 -20 0 20-60

-50

-40

-30

-20

-10

0

10

20

30

Z (m)

X (

m)

120 m

S-bandRF Gun

1.3 GeV S-band Linac

DampingRing Beam

Transport

Inflector

CouplingCorrectionβ-matchFinal Focus

Dump

FinalDoublet

EXT

INJLaserwire

XSR

Laserwire

e-

IPBSM10 μ W wires

(x/y)screen

EmittanceMeasurement

5 × WS, 4 × OTR10 μ W wires

(x/y/+10°/-10°)

PIP WS10 μ W wires

(x/y/45°)5 μ C wires

(y/+1.3°/-1.3°)

ATF / ATF2 Schematic Layout

FOBO

2/31


Injector system and Damping Ring can provide single-bunch beam or multi-bunch beam• up to Q=2×1010

• 1-20 bunches per train• 1, 2, or 3 trains

Minimum Damping Ring emittances achieved (c.2004)• εx = 1.5 nm• εy = 4 pm• Y. Honda, et al., PRL92(2004)054802

Parametersparameter design May 2010 unit

frep 1.56 1.56 Hz

Q 2-10 ~5 109 e-/bunch

E 1.3 1.282 GeV

γεx (DR) 3.0 4.8 10-6 m

γεy (DR) 3.0 3.1 10-8 m

εx (EXT) 1.2 1.9 nm

εy (EXT) 12.0 12.5 pm

σz 8 8 mm

σδ 0.08 0.08 %

βx* 4.0 40.0 mm

βy* 0.1 1.0 mm

η'x* 0.1394 0.1394 rad

σx* 2.2 8.7 μm

σy* 37 112 nm3/31

M. Woodley 410th ATF2 Project Meeting, June 30 2010

EMITTANCE & COUPLINGMEASUREMENT & CORRECTION


XSR SRIF

LW

00 modeσy = 4.1 μm

01 modeσy = 3.2 μm

ATF2design

σy ~ 5 μm σy ~ 5 μm

5/31


QM7R: pole-tip radius = 16 mm … extracted beam offset = 22.5 mm

Tokin 3393 (Ф = 32 mm)

6/31


K1L

K0L

K2L

QM7R replaced with larger bore (Ф = 42 mm) quadrupole in January 2009

K1L = 0.3 m-1 = 0.76 nominal optics mismatch

K2L = 46.6 m-2

x-y coupling for vertically off-axis beam: factor ~ 2-3 × y for y = 1 mm (εx:εy = 100:1)

Tokin 3393 (Ф = 32 mm)

PRIAM simulation

K1L = 0.392 m-1 = 0.99 × nominal K2L = 1 m-2

Tokin 3581 (Ф = 42 mm)

Measured

7/31


0 2 4 6 8 10 12 14-1.2

-1

-0.8

-0.6

-0.4

-0.2

0

0.2

Y

(m

m)

S (m)

KE

X1

QM

6R

QM

7R

BS

1X

BS

2X

BS

3X

BH

1X

QS

1X

Q

F1X

QD

2X

QF

3X

ZV

100R

X

ZV

1X

ZV

2X

ZV

3X

BS3X roll = 4.66 mrad

BS3X roll = 4.66 mradIzv1 = -6.918 (-6.976) ampIzv2 = 1.270 ( 0.965) ampchi2 = 0.3102

Observed that first 2 EXT vertical correctors (ZV1X and ZV2X) needed to be strong to properly launch into EXT (since before EXT rebuild for ATF2 … )

• hypothesize that correctors are compensating for a kick error in extraction channel• simulate error kick by rolling individual elements; use ZV1X and ZV2X to correct orbit• find error that gives best fit to actual ZV1X/ZV2X values → BS3X septum magnet roll• BS3X was physically rolled ~ -4 mrad (March 17, 2010) to relieve ZV1X and ZV2X• projected vertical emittance in EXT before coupling correction was improved

(~20-40 pm before → ~10-20 pm after)

-9 -8 -7 -6 -5 -4 -3 -2 -1 0 1-0.6

-0.4

-0.2

0

0.2

0.4

0.6

0.8

1

1.2

1.4SET-file values (April 2009 - May 2010)

ZV

2X C

urre

nt (

A)

ZV1X Current (A)

before March 17, 2010

after March 17, 2010

8/31


Date Nwire Emit (nm) BMAG

May 18 2010 4 1.905 ± 0.078 1.08 ± 0.03

Apr 21 2010 4 1.212 ± 0.065 1.26 ± 0.03

Mar 17 2010 BS3X rolled ~4 mrad (CCW)

Feb 25 2010 4 1.868 ± 0.336 1.15 ± 0.12

Feb 17 2010 4 negative

Feb 3 2010 4 1.626 ± 0.095 1.10 ± 0.06

Jan 28 2010

Dec 8 2009 3 2.921 ± 0.129 1.05 ± 0.03

Date Nwire Emit (pm) BMAG

May 18 2010 5 11.7 ± 2.3 1.43 ± 0.25

Apr 21 2010 5 15.4 ± 2.0 1.78 ± 0.17

Mar 17 2010 BS3X rolled ~4 mrad (CCW)

Feb 25 2010 5 38.33 ± 1.1 1.10 ± 0.02

Feb 17 2010 5 22.6 ± 1.4 1.15 ± 0.04

Feb 3 2010 5 16.1 ± 0.7 1.06 ± 0.03

Jan 28 2010 5 31.6 ± 1.2 1.03 ± 0.01

Dec 17 2009 5 28.4 ± 1.7 1.01 ± 0.01

Dec 8 2009 4 32.2 ± 1.9 1.35 ± 0.13

Horizontal EXT Emittance Measurements Vertical EXT Emittance Measurements

Anomalous DR → EXT vertical emittance growth fixed (?)

9/31


25 30 35 40 45 500

2

4

6

8

10

12

14

16

18

20

Be

ta (

m)

S (m)

EXT Diagnostic Section (version 4.2a)

SQ SQ WS WS WS WS WS

90°90°

180°90°

90°90°

– x– y

11°17°

28°29°

42°43°

29°29°

78.210.3

151.26.9

86.312.0

149.36.8

84.312.1σ (μm)

7 < σx/σy < 2210° wire orientation is optimal

for beam tilt measurement

SQ SQ

OTR OTR OTR OTR

Δψ

ILC “orthonormal”coupling correction

system

10/31


• projected vertical emittance (εy) reduced to 11.5 pm using QK1X• required 57 individual wire scans per QK1X setting

– X (MW1X / MW2X / MW3X / MW4X) × 3– Y (MW0X / MW1X / MW2X / MW3X / MW4X) × 3– +10° (MW0X / MW1X / MW2X / MW3X / MW4X) × 3– -10° (MW0X / MW1X / MW2X / MW3X / MW4X) × 3

• elapsed time: 7 hours for 5-point scan (!) … need multi-OTR to speed up• realistically: 90 minutes for one 5-point QK scan (4 Y wires × 3 scans at each point)

EmitY

(pm

)

Coupling correction: single skew quadrupole scan

11/31

M. Woodley

○ 100°* 80°

Coupling reconstruction• Projected beam size measurements at x, 80o, y and

100o at 4 wire-scanner positions varying the

strength of the QK1X skew quadrupole

• Coupling reconstruction using:

• Verification of the consistency of 80o and 100o measurements

• Search for an algorithm to reconstruct the beam matrix at QK1X position:

The more reliable method consists of:

Coupling measurements in ATF2 EXT (1) [Cecile Rimbault]

cos2

sin

sin2

cos

sincos23311

2

13

a. Constrain 6 elements with s33 fitsb. Constrain 3 elements with s13 fitsc. Constrain the last one with s11 fits

ARk

ABRRRk

CABRRRR

QK

QKQK

QKQKQKM

11234

2

14234133433

244

23434343333

23333

2)(2

2

ARk

ABRRRk

CABRRRR

QK

QKQK

QKQKQKM

33212

2

23212131211

222

21212121111

21111

2)(2

2

ARRk

ABRRRRRRk

CABRRRRRRRR

QK

QKQKQKQK

QKQKQKQKM

1334122

34123412333312113411

224341223123314341113331113

2))((


M. Woodley

Coupling measurements in ATF2 EXT (2) [Cecile Rimbault]

Comparison between measurements and beam matrix reconstruction result propagation

s33 s13

at QK1X

- physical results but large error bars (not to mention imaginary εy!) - large number of data sets is required to minimize statistical errors- analysis algorithm must guarantee positive-definite beam matrix



4. All 4 OTRs installed as of June 15. Target inserters, movers, cameras,

controls, software … all OK6. All 4 OTR targets melted during checkout!

• thin aluminized mylar target (1200 Å Al)• Prosilica camera (3.75 μm / pixel)

14/31


pixe

lspi

xels

pixels

ATF2 EXT OTR1

ok …

… melted

• June 2, 2010• single bunch beam• Q ≈ 4×109 e-/bunch (0.64 nC)• 1.56 Hz• σx ≈ 140 μm ; σy ≈ 10 μm• 2 μm nitrocellulose / 1200 Å Al• ~4 minutes in beam until damage

• damaged targets will be replaced> 6 μm kapton / 1200 Å Al> 100 μm Al foil

• 10 μm tungsten X/Y wires will be added to target holders

scribeline

15/31


DISPERSIONMEASUREMENT & CORRECTION


Flight Simulator DispersionMeasurement / Correction

17/31


Before Correction After Correction

ηx

η'x

IQF1X (amp) IQF6X (amp)

Response Matrix Measurement

HorizontalDispersionCorrection

18/31


0

10

20

1/2

XY

-0.75-0.5

-0.250

0.250.5

0.75

0 5 10 15 20-1

0

1

S (m)

KE

X1

BS

1X

BS

2X

BS

3X

BH

1X

BH

2X

BH

3X

KE

X2

QM

6R

QM

7R

QF

1X

QD

2X

QF

3X

QF

4X

QD

5X

QF

6X

QF

7X

QD

8X

QS1X QS2X

“Sum-Knob”: IQS1X = IQS2X

Simulated ηy* (right) and η'y* (right),back-propagated from IP

Vertical Dispersion Correction(FD-phase)

Δ Sum-Knob = -0.15 A

IP-phase FD-phase

19/31


2010/ 2/ 18 10mm at IP

The old orbit had a large offset around QF21X, QM16FF.I applied careful orbit tuning around QF21X, QM16FF with FF mover.

2010/ 2/ 25 1mm at IP

2010/ 3/ 18 2mm at post-IP

We used the fast kicker for the beam extraction.

We switched back to SLAC kicker.

2010/ 4/ 7 3.8mm at post-IP

2010/ 4/ 8 3.6mm at post-IP 3.6mm at IP

Dispersion for 4/7 QS1X= -1A QS2X= -1A

Dispersion for 4/8 QS1X= -2.8A QS2X= -2.8A

Summary of Vertical Dispersion at IP

IP dispersion is not sensitive to Sum-knob

From Okugi-san’s presentation (ATF Ops 2010.04.09)

20/31


BETA MATCHING


*

*

* *

100 01 cos sin11

00 1 sin cos00

ms

m

RI =

waist shift magnification phase shift (α* 0)

alphaknob

betaknob

phaseknob

“Irwin Knobs” for β-matching : R = RI × R0

“Irwin Knobs”

40 45 50 55 60 65 70 75 80 85-2.5

-2.25

-2

-1.75

-1.5

-1.25

-1

-0.75

-0.5

-0.25

0

(ra

d/2

)

S (m)

B5

FF

B2

FF

B1

FF

QD

18

X

QF

19

X

QD

20

X

QF

21

X

QM

16

FF

QM

15

FF

QM

14

FF

QM

13

FF

QM

12

FF

QM

11

FF

QD

10

BF

F

QD

10

AF

F

QF

9B

FF

QF

9A

FF

QD

8F

F

QF

7F

F

QD

6F

F

QF

5B

FF

QF

5A

FF

QD

4B

FF

QD

4A

FF

QF

3F

F

QD

2B

FF

QD

2A

FF

QF

1F

F

QD

0F

F

SF

6F

F

SF

5F

F

SD

4F

F

SF

1F

F

SD

0F

F

ATF2 pulse-to-pulse feedback devices (v3.7)

XY

R0

Final Focus

22/31


• get initial magnet strengths from control system, compute R0

• for a desired knob type, compute RI(n) for a small step in s, m, or ψ– small steps required due to nonlinear ΔKLQ/ΔKnob

• set R=RI(n)*R0 to make one knob step• use MAD matching to fit to desired elements of R using FF matching quadrupoles• changes to magnet strengths tend to be symmetric in the knob value … computed

strengths for quadrupoles that start at zero tend to go bipolar• tried waist shift and magnification knobs during tuning week … seem OK

23/31


-4 -2 0 2 419.6

19.8

2020.2

20.420.6

20.8

QM

16

FF

(a

mp

s)

-4 -2 0 2 427

27.2

27.4

QM

15

FF

(a

mp

s)

-4 -2 0 2 455

56

57

58

QM

14

FF

(a

mp

s)

-4 -2 0 2 436

36.5

37

37.5

QM

13

FF

(a

mp

s)

-4 -2 0 2 4

14

15

16

17

QM

12

FF

(a

mp

s)

Wy (mm)

-4 -2 0 2 4

-0.2

0

0.2

QM

11

FF

(a

mp

s)

QM*FF Currents (amps)IP Twiss Parameters

-4 -2 0 2 4

3.8

4

4.2

4.4

x (cm

)

-4 -2 0 2 4-1

-0.5

0

0.5

1

x

-4 -2 0 2 4-1

-0.5

0

0.5

1

x (

de

g)

-4 -2 0 2 4

5

10

15

20

25

y (m

m)

-4 -2 0 2 4

-4

-2

0

2

4

y

Wy (mm)

-4 -2 0 2 4

-10

-5

0

5

10

y (

de

g)

Vertical Waist Scan (±5β*) [BX10BY10 optics]

24/31


Vertical Magnification Scan (0.5-2) [BX10BY10 optics]


0.5 1 1.5 2

3.8

4

4.2

4.4

x (cm

)

0.5 1 1.5 2-1

-0.5

0

0.5

1 x

0.5 1 1.5 2-1

-0.5

0

0.5

1

x (

de

g)

0.5 1 1.5 20.5

1

1.5

y (m

m)

0.5 1 1.5 2-1

-0.5

0

0.5

1

y

My

0.5 1 1.5 2-1

-0.5

0

0.5

1

y (

de

g)

0.5 1 1.5 2

18

20

22

24

QM

16

FF

(a

mp

s)

0.5 1 1.5 2

26

27

28

29

QM

15

FF

(a

mp

s)

0.5 1 1.5 2

55

60

65

QM

14

FF

(a

mp

s)

0.5 1 1.5 2

34

36

38

QM

13

FF

(a

mp

s)

0.5 1 1.5 2

10

15

20

QM

12

FF

(a

mp

s)

My

0.5 1 1.5 2-1

0

1

QM

11

FF

(a

mp

s)

0

*

y y y*M My

y

m

25/31



Vertical Phase Scan (0-90°) [BX10BY10 optics]

0 50

3.8

4

4.2

4.4

x (cm

)

0 50-1

-0.5

0

0.5

1

x

0 50

-500

0

500

x (

de

g)

0 500.9

0.95

1

1.05

y (m

m)

0 50-1

-0.5

0

0.5

1

y

y (deg)

0 500

20

40

60

80

y (

de

g)

0 50

22

24

26

28

30

QM

16

FF

(a

mp

s)

0 50

28

30

32

34

36

QM

15

FF

(a

mp

s)

0 5060

80

100

QM

14

FF

(a

mp

s)

0 50

38

40

42

QM

13

FF

(a

mp

s)

0 50

8

10

12

14

16

QM

12

FF

(a

mp

s)

y (deg)

0 500

0.5

1

1.5

QM

11

FF

(a

mp

s)

26/31


30 40 50 60 70 800

5

10

15

20

25

30

35

40

B5F

F

B2F

F

B1F

F

QF

9X

QD

10X

QF

11X

QD

12X

QF

13X

QD

14X

QF

15X

QD

16X

QF

17X

QD

18X

QF

19X

QD

20X

QF

21X

QM

16F

F

QM

15F

F

QM

14F

F

QM

13F

F

QM

12F

F

QM

11F

F

QD

10B

FF

Q

D10

AF

F

QF

9BF

F

Q

F9A

FF

QD

8FF

QF

7FF

QD

6FF

QF

5BF

F

Q

F5A

FF

QD

4BF

F

Q

D4A

FF

QF

3FF

QD

2BF

F

QD

2AF

F

QF

1FF

QD

0FF

SF

6FF

SF

5FF

SD

4FF

SF

1FF

SD

0FF

R0

QK1X QK2X QK3X QK4X

RI =

0

0

0

0

h c d

h a b

b d h

a c h

2

2

,

cos and sin when 0

cosh and sinh when 0

skewH axy bxy cx y dx y

H Hy y

y y

h ad bc

h

“Irwin Knobs” for coarse coupling correction: R = RI × R0

27/31


Summary (1)• improvements made to both hardware and diagnostics may have cured the

anomalous vertical emittance growth at extraction from the Damping Ring that has been observed for many years– QM7R replacement– BS3X roll– DR emittance diagnostics (XSR, SRIF, LW)

• the new EXT multi-OTR system should improve our ability to measure and correct emittance– faster emittance measurement and skew quad optimization– possibility of 4D beam-matrix measurement / reconstruction / correction

• Flight Simulator dispersion measurement / correction software seems to work– excellent improvements in BPM resolution and reliability make it possible– propagation of dispersion fits to wire scanners, IP, PIP, etc.– correction of FD-phase ηy with sum-knob

– model-based ηx correction with QF1X/QF6X sometimes has trouble, but “manual” correction works

– jitter-based (SVD) dispersion measurement / monitoring still a possibility

28/31


Summary (2)• Flight Simulator “Irwin” knobs provide possibility of orthogonal “manual” β-

matching– QM*FF only … FF / FD magnets can remain at design strengths– orthogonal waist and β control– orthogonal phase control … intriguing possibilities (vertical dispersion, feedback, … )– control of IP x-y and x'-y coupling may also be possible

29/31


Ongoing Work (1)• need to archive future EXT multi-wire and multi-OTR emittance measurements

– raw beam sizes, raw dispersion data, wire-to-wire and IEX to MW0X R-matrices– analysis results (with errors)

• coupling measurement / 4D beam reconstruction– acquire full data set (X/Y/U/+10/-10) plus raw data files for all EXT wires– cross-check raw data normalization and who’s who … is everything OK now?– acquire OTR beam images for all EXT OTRs and extract lengths of semi-major and semi-

minor axes and ellipse tilt angles– try 4D reconstruction … Ilya Agapov’s “Cholesky decomposition” method?

• consistency checks for emittance and Twiss– forward propagate from EXT– backward propagate from IP

• Flight Simulator computer control of Damping Ring RF frequency ramp

30/31


Ongoing Work (2)

• find a better “coarse” IP-phase ηy knob– closed bump in FF matching quadrupole region?– generate in Damping Ring?– is there a way to use the “Kubo bump” to control IP-phase vertical dispersion?

• Flight Simulator “Irwin” knob development– GUI– FF optics with all QM*FF ON at reasonable currents– coupling knobs

• revisit SLAC epoxy kicker multipoles (if we don’t switch to fast stripline extraction permanently)– are observed EXT BMAG values consistent?– why are vertical bumps at KEX1 closed? are the kickers identical?– is there a way to use the “Kubo bump” to control IP-phase vertical dispersion?

• and on and on …

31/31

EXT Beam Measurements & Corrections

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Transcript of EXT Beam Measurements & Corrections