Commissioning Status of the LCLS Accelerator and Undulator Systems

1 Henrik [email protected]

1LCLS Commissioning StatusPulse Seminar 4/3/2009

Commissioning Status of the LCLS Accelerator and Undulator Systems

Henrik Loos

for the LCLS Commissioning Team



Overview

LCLS IntroductionAccelerator Commissioning

EmittanceLaser HeaterBunch CompressionFeedbackStability

Undulator CommissioningDiagnosticsBeam Based AlignmentSpontaneous Radiation

Outlook



Linac Coherent Light Source at Linac Coherent Light Source at SLACSLAC

Injector (35Injector (35ºº))at 2-km pointat 2-km point

Existing 1/3 Linac (1 km)Existing 1/3 Linac (1 km)(with modifications)(with modifications)

Near Experiment HallNear Experiment Hall

Far ExperimentFar ExperimentHallHall

Undulator (130 m)Undulator (130 m)

X-FEL based on last 1-km of existing linacX-FEL based on last 1-km of existing linacX-FEL based on last 1-km of existing linacX-FEL based on last 1-km of existing linac

New New ee Transfer Line (340 m) Transfer Line (340 m)

1.5-15 Å1.5-15 Å1.5-15 Å1.5-15 Å

X-ray X-ray Transport Transport Line (200 m)Line (200 m)



X-rays in spring 2009X-rays in spring 2009SLAC linac tunnelSLAC linac tunnel research yardresearch yard

Linac-0Linac-0L L =6 m=6 m

Linac-1Linac-1L L 9 m9 m

rf rf 25°25°

Linac-2Linac-2L L 330 m330 mrf rf 41°41°

Linac-3Linac-3L L 550 m550 mrf rf 0° 0°

BC1BC1L L 6 m6 m

RR5656 39 mm39 mm

BC2BC2L L 22 m22 m

RR5656 25 mm25 mm DL2 DL2 L L =275 m=275 mRR56 56 0 0

DL1DL1L L 12 m12 mRR56 56 0 0

undulatorundulatorL L =130 m=130 m

6 MeV6 MeVz z 0.83 mm 0.83 mm 0.05 %0.05 %

135 MeV135 MeVz z 0.83 mm 0.83 mm 0.10 %0.10 %

250 MeV250 MeVz z 0.19 mm 0.19 mm 1.6 %1.6 %

4.30 GeV4.30 GeVz z 0.022 mm 0.022 mm 0.71 %0.71 %

13.6 GeV13.6 GeVz z 0.022 mm 0.022 mm 0.01 %0.01 %

Linac-Linac-XXL L =0.6 m=0.6 mrfrf= =

21-1b,c,d

...existinglinac

L0-a,b

rfrfgungun

21-3b24-6dX

25-1a30-8c

undulatorundulator

Commission Mar-Aug 2007Commission Mar-Aug 2007 Commission Jan-Aug 2008Commission Jan-Aug 2008 Dec 2008…Dec 2008…

be

am

pa

rked

he

reb

ea

m p

arke

d h

ere

LCLS Accelerator Layout



LCLS Beam Diagnostics

BC2BC24.3 GeV4.3 GeV

BSYBSY14 GeV14 GeV

TCAV3TCAV35.0 GeV5.0 GeV

BC1BC1250 MeV250 MeV

L1SL1S

3 wires3 wires2 OTR2 OTR

L1XL1X4 wire4 wire

scannersscanners

L2-linacL2-linac L3-linacL3-linacDL1DL1

135 MeV135 MeV

L0L0gungun TCAV0TCAV0 oldold

screenscreen3 OTR3 OTR

zz11 zz223 wires3 wires3 OTR3 OTR stopperstopper

heaterheater

w

all

wal

l

DL2DL214 GeV14 GeV

undulatorundulator14 GeV14 GeV

4 wire4 wirescanners +scanners +

4 collimators4 collimators vert.vert.dumpdump

2 Transverse RF cavities (135 MeV & 5 GeV)2 Transverse RF cavities (135 MeV & 5 GeV)

~195 BPMs and toroids~195 BPMs and toroids

7 YAG screens (at 7 YAG screens (at EE 135 MeV)135 MeV)

12 OTR screens at 12 OTR screens at EE 135 MeV 135 MeV

15 wire scanners (each with x & y wires)15 wire scanners (each with x & y wires)

CSR/CER pyroelectric bunch length monitors at BC1 & BC2CSR/CER pyroelectric bunch length monitors at BC1 & BC2

4 beam phase monitors (2856 – 51 MHz)4 beam phase monitors (2856 – 51 MHz)

Gun spectrometer line + injector spectrometer lineGun spectrometer line + injector spectrometer line

• YAG screensYAG screens• OTR screensOTR screens• Wire scannersWire scanners

• YAG screensYAG screens• OTR screensOTR screens• Wire scannersWire scanners



Injector Emittance Commissioning

-8 -7 -6 -50

50

100

150

Bea

m S

ize

( m

)

-1 -0.5 0 0.5 1

-1

-0.5

0

0.5

1

Nor

m. A

ngle

-8 -7 -6 -50

50

100

150

QUAD:IN20:525:BDES (kG)

Bea

m S

ize

( m

)

-1 -0.5 0 0.5 1

-1

-0.5

0

0.5

1

Norm. Position

Nor

m. A

ngle

-8 -7 -6 -50

50

100

150

Bea

m S

ize

( m

)

-1 -0.5 0 0.5 1

-1

-0.5

0

0.5

1

Nor

m. A

ngle

-8 -7 -6 -50

50

100

150

QUAD:IN20:525:BDES (kG)

Bea

m S

ize

( m

)

-1 -0.5 0 0.5 1

-1

-0.5

0

0.5

1

Norm. Position

Nor

m. A

ngle

Q = 250 pCE = 135 MeV

Q = 250 pCE = 135 MeV

γεy = 0.86 μmγεy = 0.86 μm

γεx = 0.83 μmγεx = 0.83 μm

Emittance measured at OTR screen with upstream quad scanfor 95% charge

Emittance measured at OTR screen with upstream quad scanfor 95% charge

For 1 nCγεx= 1.07 μmγεy= 1.11 μm

For 1 nCγεx= 1.07 μmγεy= 1.11 μm

Iterative Optimization with gun solenoid & quads, steering correctors, and matching to design Twiss

Iterative Optimization with gun solenoid & quads, steering correctors, and matching to design Twiss

Measured emittance meets requirement for FELMeasured emittance meets requirement for FEL



New LTU Wire-Scanners Working Well

Emittance to upstream of undulator (mostly) preservedEmittance to upstream of undulator (mostly) preserved

-40 -20 0 20 40 60 800

10

20

30

40

Position (m)

Bea

m S

ize

(m

)

Emittance Scan on WIRE:LTU1:735 19-Jan-2009 20:20:43 Gaussian

E = 13.634 GeVQ = 0.250 0.01 nC

y = 0.99 0.01 ( 1.00) m

y = 47.74 0.59 (46.23) m

y = 1.12 0.02 ( 1.08)

y = 1.00 0.00 ( 1.00)

2/NDF = 0.06

-1 -0.5 0 0.5 1

-1

-0.5

0

0.5

1

Norm. Position

Nor

m. A

ngle

Normalized Phase Space

-40 -20 0 20 40 60 800

10

20

30

40

Position (m)

Bea

m S

ize

(m

)

Emittance Scan on WIRE:LTU1:735 19-Jan-2009 20:20:43 Gaussian

E = 13.634 GeVQ = 0.250 0.01 nC

y = 0.99 0.01 ( 1.00) m

y = 47.74 0.59 (46.23) m

y = 1.12 0.02 ( 1.08)

y = 1.00 0.00 ( 1.00)

2/NDF = 0.06

-1 -0.5 0 0.5 1

-1

-0.5

0

0.5

1

Norm. Position

Nor

m. A

ngle

Normalized Phase Space

Emittance horizontal 1.1umEmittance horizontal 1.1um



YAGS2YAGS2

Laser Laser OFFOFFσσEE//EE < 12 keV < 12 keV

RF deflector RF deflector ONON

timetimeenergyenergy

Dec. 10, 2008Dec. 10, 2008

Laser-Heater Working Well

YAGS2YAGS2

Laser: Laser: 40 40 µµJJσσEE//EE 45 keV 45 keV

YAGS2YAGS2

Laser: Laser: 230 230 µµJJσσEE//EE 120 keV 120 keV



Double-horn is Double-horn is consistent with consistent with laser beam laser beam presently ~50% presently ~50% larger in larger in transverse size transverse size than electron than electron beambeam

Laser energy 230 Laser energy 230 µµJJσσEE//EE 120 keV 120 keV

YAGS2YAGS2 YAGS2YAGS2

Laser OFFLaser OFF

Laser-Heater Working Well



-35 -30 -25 -20 -15 -10 -5 00

20

40

60

80

100

120

BC2 R56 (mm)

s ( m

)

MeasuredElegant

-35 -30 -25 -20 -15 -10 -5 00

20

40

60

80

100

120

BC2 R56 (mm)

s ( m

)

MeasuredElegant

Bunch Compression in BC2

Q = 0.25 nCσz ≈ 2 μm

Q = 0.25 nCσz ≈ 2 μm

89.6 89.8 90 90.2

-2000

-1500

-1000

-500

0

500

1000

1500

2000

TCAV Phase (Degree)

Bea

m p

ositi

on (

m)

5515.20244.23 m/degree

89.6 89.8 90 90.2

-2000

-1500

-1000

-500

0

500

1000

1500

2000

TCAV Phase (Degree)

Bea

m p

ositi

on (

m)

5515.20244.23 m/degree

-1 -0.5 0 0.5 10

50

100

150

200

250

300

TCAV Gradient (norm.)

Bea

m S

ize

( m

)

y = 242.49 0.95 m

z = 7.2870.452 m

-1 -0.5 0 0.5 10

50

100

150

200

250

300

TCAV Gradient (norm.)

Bea

m S

ize

( m

)

y = 242.49 0.95 m

z = 7.2870.452 m

CalibrationCalibration MeasurementMeasurement

VV00 ≤≤ 20 MV 20 MV

ee

zz

2.44 m2.44 m

cc pp 90°90°

VV((tt)) yy

RFRF‘‘streak’streak’

SS-band-band

Bunch Length vs. CompressionBunch Length vs. Compression



CSR Emittance Growth in BC2

Beam emittance can grow due to coherent synchrotron radiation effects during bunch compression

Compare measurements with simulation code

Confirms 100% projected emittance growth at nominal compression

Slice emittance not effected at operating point

Emittance growth mechanisms well understood

Beam emittance can grow due to coherent synchrotron radiation effects during bunch compression

Compare measurements with simulation code

Confirms 100% projected emittance growth at nominal compression

Slice emittance not effected at operating point

Emittance growth mechanisms well understood -35 -30 -25 -20 -15 -10 -5 0

0

1

2

3

4

5

BC2 R56 (mm)

x (

m)

MeasuredElegant projectedElegant slice

0

20

40

60

80

100

120

s ( m

)

MeasuredElegant

-35 -30 -25 -20 -15 -10 -5 00

1

2

3

4

5

BC2 R56 (mm)

x (

m)

MeasuredElegant projectedElegant slice

0

20

40

60

80

100

120

s ( m

)

MeasuredElegant

Y. Ding, Z. HuangY. Ding, Z. Huang



Longitudinal Loops Stabilize:Longitudinal Loops Stabilize:DL1 energyDL1 energyBC1 energyBC1 energyBC1 bunch lengthBC1 bunch lengthBC2 energyBC2 energyBC2 bunch lengthBC2 bunch lengthFinal energyFinal energy

Transverse Loops Stabilize:Transverse Loops Stabilize:Laser spot on cathodeLaser spot on cathodeGun launch angleGun launch angleInjector trajectoryInjector trajectoryX-band cavity positionX-band cavity positionLinac & LTU trajectory (5)Linac & LTU trajectory (5)Undulator trajectoryUndulator trajectory

Laser & Electron-Based Feedback Systems

L0L0

gungun

L3L3L2L2XX

DL1 BC1 DL2L1L1

zz11

1111 VV11

zz22

2222 VV22

33

VV33

00VV00

D. Fairley,D. Fairley,J. WuJ. Wu BC2

BPMsBPMsCER detectorsCER detectors

Steering LoopSteering LoopLaserLaser



LCLS Beam Stability

-1 0 1-1

0

1

x

x'

-1 0 1-1

0

1

yy'

-1 0 1-1

0

1

x

x'

-1 0 1-1

0

1

y

y'-1 0 1

-1

0

1

x

x'

-1 0 1-1

0

1

yy'

-1 0 1-1

0

1

x

x'

-1 0 1-1

0

1

y

y'

Linac

InjectorBeam positionLaser: 3%Injector: 4% at 250 MeVLinac: 10-15% at 9 GeVUndulator: ~20%Goal is 10%

Bunch lengthBC1: 5% at 250 ABC2: 8% at 3000 A

Charge & EnergyΔQ/Q ≈ 1.5%ΔE/E ≈ 0.03% at 13.6 GeV

Beam positionLaser: 3%Injector: 4% at 250 MeVLinac: 10-15% at 9 GeVUndulator: ~20%Goal is 10%

Bunch lengthBC1: 5% at 250 ABC2: 8% at 3000 A

Charge & EnergyΔQ/Q ≈ 1.5%ΔE/E ≈ 0.03% at 13.6 GeV

1-1- beam beam sizesize

D. RatnerD. Ratner

Feedback system keep machine stable for short-term …Feedback system keep machine stable for short-term …



Electron Beam Reaches Brightness for 1.5 Å

Gain length and saturation power calculated from measured electron beam parameters

07/07 07/08 07/09 07/10 07/11 07/12 07/13 07/140

2

4

6

8

10

12

Time

L Gai

n (m

), P

Sat

(G

W),

(

Å)

07/07 07/08 07/09 07/10 07/11 07/12 07/13 07/140

2

4

6

8

10

12

Time

L Gai

n (m

), P

Sat

(G

W),

(

Å)

FEL Power Prediction3D Gain Length

FEL Power Prediction3D Gain Length

… and for long-term!… and for long-term!



LCLS Undulator Configuration

33 Undulator segments on individual girders (21 installed)Undulator, Quad, BPM, BFW move with girderBeam Finder Wire (BFW) retractableGirder alignment with BFW at upstream and BBA at downstream end

In/Out

Scan

Beam

Undulator Quad RF BPM

Girder

BFW

Corr

Girder Movers



22ndnd shot (all the shot (all the way to dump)way to dump)

11stst shot (stops in shot (stops in just into undulator)just into undulator)

BPMs mistimedBPMs mistimed

First Beam to Main Dump



……also emittance measured using 4 BFW’salso emittance measured using 4 BFW’s

Centering Works WellCentering Works Well

66 Beam Finder Wires (BFW) Tested and Aligned



Undulator Re-Pointing is Tested

Enables motion of the entire undulator to steer electron beam and X-rays to a new axis

Enables motion of the entire undulator to steer electron beam and X-rays to a new axis



using girder motion vs. BPM readingusing girder motion vs. BPM reading

6% rms scale variation in X (will be improved)6% rms scale variation in X (will be improved)

6% rms scale variation in Y (will be improved)6% rms scale variation in Y (will be improved)

fixedfixed

Undulator Cavity BPMs Calibrated with Beam



Beam Based Alignment Schematic

Δq1 Δq3Δq2

Δb1 Δb3Δb2

Δy1 Δy3Δy2Δy0 Δy4

Δb0Δb0

E1

E2

BPM Offsets Δbi

Quad Offsets Δqi

x,x’

E1 < E2

BPM and quadrupole offsets are unknownVary energy, measure orbit to determine straight line



Final Final Round of Round of Beam-Beam-Based Based AlignmentAlignment

40 40 µµmm

100 100 µµmm RMS = 64 RMS = 64 µµmm

RMS = 26 RMS = 26 µµmm

Earth’s field Earth’s field patternpattern

Verify Verify alignment alignment with quad with quad strength strength variationsvariations

Undulator Beam-Based Alignment Converged



Dispersion-Free (from 4.3 to 13.6 GeV)Dispersion-Free (from 4.3 to 13.6 GeV)

Undulator Beam-Based Alignment Converged

20 20 mm

5 5 mm



Photo is just an Photo is just an example, and example, and not U-25not U-25

Undulator Magnet Installed at U-25 (of 33)



20 BPMs in a 6-parameter fit (X0, X0', Y0, Y0', Xkick, Ykick) has a 0.5 20 BPMs in a 6-parameter fit (X0, X0', Y0, Y0', Xkick, Ykick) has a 0.5 µµm Xrms fit residual and a 0.3 µm Yrms fit residual (NAVG=25).m Xrms fit residual and a 0.3 µm Yrms fit residual (NAVG=25).

High resolution RF-BPMs

RF-BPMs Resolve 10 nrad Kicks (~300 nm resolution)



Beam-Based Measurements (U25)Beam-Based Measurements (U25)

MMF Measurements (U25)MMF Measurements (U25)

IX1IX1IY1IY1

IX1IX1

IY1IY1

Beam-Based Measured Field Integrals

Beam-based measurement agrees with MMF data



0.7 0.7 mmbacklasbacklas

hh

yy = 30 nrad kick due to quad = 30 nrad kick due to quad

±±4 4 mm

3-parameter fit 3-parameter fit to 20 cavity to 20 cavity BPMs along the BPMs along the undulator (undulator (yy00, ,

yy00, and , and yy))

Feb. 7, 2009Feb. 7, 2009

((yy00, , yy00))

Measured Undulator Girder Backlash (<1 mm)



Wakefield Energy-Loss in the LCLS Undulator

Wake field energy loss agrees well with theory

Important to adjust taper of undulator correctly

Wake field energy loss agrees well with theory

Important to adjust taper of undulator correctly



84 meters of Undulator Installed



Observation of Undulator Radiation

Spontaneous X-Rays (U25 undulator only)Spontaneous X-Rays (U25 undulator only)

Radiation from dump bendsRadiation from dump bends

Used to measure X-ray energy at K-edge of YAG crystal absorption



Gas Detector

Gas Attenuator

Direct Imager(Scintillator)

FEL Offset Mirror Systems

Beam Direction

SolidAttenuators

K-Monochromator

Thermal Sensor

Slit

Collimators

Pop-in cameras

Pop-in cameras

Reticule

C0 collimator (in e- beam dump

Fixed Mask

GasDetector

X-Ray Diagnostics in the Front End Enclosure



Summary

Accelerator commissioned mostly to design goalsAccelerator commissioned mostly to design goals

Laser heater commissioned and working well (does not salvage OTR Laser heater commissioned and working well (does not salvage OTR screen quantitative use – many MPS problems)screen quantitative use – many MPS problems)

Beam-based alignment converged to required level (should improve Beam-based alignment converged to required level (should improve after undulators installed due to after undulators installed due to µµ-shielding of Earth’s field)-shielding of Earth’s field)

New LTU wire scanners working routinelyNew LTU wire scanners working routinely

Cavity BPMs commissioned and working fantasticallyCavity BPMs commissioned and working fantastically

One undulator field integrals confirmed with beamOne undulator field integrals confirmed with beam

21 undulators installed21 undulators installed

Full motion control on all girders (+ 21 undulators) working wellFull motion control on all girders (+ 21 undulators) working well

All beam finder wires (BFW) checked out and aligned with beamAll beam finder wires (BFW) checked out and aligned with beam

BFW’s also used successfully to measure emittanceBFW’s also used successfully to measure emittance

Full 6x6 feedback running (some over-sensitivity to machine setup Full 6x6 feedback running (some over-sensitivity to machine setup still)still)

Soon hopefully to observe first FEL lightSoon hopefully to observe first FEL light



Tune up and run extended time (2 wks) at 4.3 GeV in Tune up and run extended time (2 wks) at 4.3 GeV in preparation for AMO runpreparation for AMO runStreamline energy change for users and for rapid beam-Streamline energy change for users and for rapid beam-based alignmentbased alignmentInstall, set up, and verify new MPS system (controls)Install, set up, and verify new MPS system (controls)Commission remaining undulatorsCommission remaining undulatorsMeasure FEL gainMeasure FEL gainCommission FEECommission FEEOptimize FELOptimize FEL

To Do



Re-establishRe-establishee to SL2 to SL2

LTU/LTU/UndUnd

Comm. Comm.

Firs

t Li

ght

in

Firs

t Li

ght

in

FEE

FEE

Firs

t Li

ght

in F

EH

Firs

t Li

ght

in F

EH

NEH Ops & NEH Ops & CommissioningCommissioning

JJJJ FFFF MMMM AAAA MMMM JJJJ JJJJ AAAA SSSS DDDD JJJJ FFFF MMMM AAAA MMMM JJJJ JJJJ AAAA SSSS OOOO NNNN DDDD JJJJ FFFF MMMM AAAA MMMM JJJJ JJJJOONNAA

2008 2009 20102008 2009 2010 2008 2009 20102008 2009 2010DownDownPPS

PPS

Linac/BC2 Linac/BC2 CommissioninCommissionin

g g FEL/FEEFEL/FEECommissioniCommissioni

ng ng Nov. 3, 2008Nov. 3, 2008

Inst

all

Inst

all U

ndula

tors

Undula

tors

MMDD

LTU

/Und

In

stall

LTU

/Und

In

stall

PEP-I

I ru

n

PEP-I

I ru

n

ends

ends

FEE/N

EH

In

stall

FEE/N

EH

In

stall

PPS C

ert

. LT

U/D

um

pPPS C

ert

. LT

U/D

um

p

CD-4

CD-4

(7

/31

/201

0)

(7/3

1/2

01

0)

X-R

ays

in N

EH

X-R

ays

in N

EH

no

wn

ow

DDDown?Down?

FEH

Hutc

h B

OFE

H H

utc

h B

O

LCLS Installation and Commissioning Time-Line



Undulator Trajectory Jitter

Energy (GeV) σx (μm) σy (μm) Beam size (μm)

13.64 9 7 33

9.25 7 7 33

7 12 6 33

4.3 18 23 36

Documents

Commissioning Status of the LCLS Accelerator and Undulator Systems