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1 Zhirong [email protected]

1LCLS First LasingUCLA, May 2009

LCLS First Lasing ResultsLCLS First Lasing Results

Z. Huang, for the Z. Huang, for the LCLSLCLS Commissioning TeamCommissioning Team

UCLAUCLA Workshop onWorkshop on"X"X--ray Science at the ray Science at the FemtosecondFemtosecond

to to AttosecondAttosecond FrontierFrontier

May 18May 18--20, 2009 20, 2009



Linac Coherent Light Source at Linac Coherent Light Source at SLACSLAC

Injector (35Injector (35ºº))at 2at 2--km pointkm 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 linacXX--FEL based on last 1FEL based on last 1--km of existing linackm of existing linac

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

1.5-15 Å1.51.5--15 15 ÅÅ

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

LLNLLLNL

UCLAUCLA



LCLS Accelerator Layout

SLAC linac tunnelSLAC linac tunnel research yardresearch yard

LinacLinac--00L L =6 m=6 m

LinacLinac--11L L ≈≈9 m9 mϕϕrf rf ≈≈ −−2525°°

LinacLinac--22L L ≈≈330 m330 mϕϕrf rf ≈≈ −−4141°°

LinacLinac--33L L ≈≈550 m550 mϕϕrf rf ≈≈ 00°°

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 MeVσσz z ≈≈ 0.83 mm0.83 mmσσδδ ≈≈ 0.05 %0.05 %



4.30 GeV4.30 GeVσσz z ≈≈ 0.022 mm0.022 mmσσδδ ≈≈ 0.71 %0.71 %

13.6 GeV13.6 GeVσσz z ≈≈ 0.022 mm0.022 mmσσδδ ≈≈ 0.01 %0.01 %

LinacLinac--XXL L =0.6 m=0.6 mϕϕrfrf= = −−160160°°

21-1b,c,d

...existinglinac

L0-a,b

rfrfgungun

21-3b24-6dX 25-1a

30-8c

undulatorundulator

Commission MarCommission Mar--Aug 2007Aug 2007 Commission JanCommission Jan--Aug 2008Aug 2008 Nov 2008Nov 2008……

First lasing at 1.5 Å: April 10, 2009 (first try!)



Injector Transverse Projected Emittance <0.5 μm

135 MeV135 MeV0.25 nC0.25 nC

35 A35 A

γεγεxx ≈≈ 0.43 0.43 μμmm

γεγεyy ≈≈ 0.46 0.46 μμmm

Exceptional beam Exceptional beam quality from Squality from S--band band CuCu--cathcath. RF gun. RF gun……

TimeTime--sliced emittance: 0.3sliced emittance: 0.3--0.4 0.4 μμmm

D. DowellD. Dowell



σσzz > 25 > 25 μμmm

BC2BC2(4.3 GeV)(4.3 GeV)

BSYBSY(14 GeV)(14 GeV)

TCAVTCAV(5.0 GeV)(5.0 GeV)

550 m550 m

σσzz < 5 < 5 μμmm

old screen usedold screen used

L2L24 wires4 wires

σσzz ≈≈ 2 2 μμmmno

min

alno

min

al

Bunch compression and CSR after BC2 (0.25 nC)



Undulator Girder with Motion Control + IN/OUT

Cavity BPM (<0.5 μm)Cavity BPM (<0.5 μm)QuadrupolemagnetQuadrupolemagnet

3.4-mundulatormagnet

3.4-mundulatormagnet

Beam Finder Wire (BFW)Beam Finder Wire (BFW)

CAM-based 5-DOF motion control

CAM-based 5-DOF motion control

beamdirectionbeamdirection

X-translation

(in/out)

X-translation

(in/out)

Wire Position MonitorWire Position Monitor

Hydraulic Level SystemHydraulic Level System

sand-filled, thermally isolated supports

sand-filled, thermally isolated supports



BeamBeam--Based Undulator AlignmentBased Undulator AlignmentMeasure undulator trajectory at 4 energies (4.3, 7.0, 9.2, & 13.Measure undulator trajectory at 4 energies (4.3, 7.0, 9.2, & 13.6 GeV)6 GeV)Scale all linac & upstream transport line magnets each timeScale all linac & upstream transport line magnets each timeDo not change Do not change anythinganything in the undulatorin the undulatorCalculateCalculate…… ((MatlabMatlab GUI)GUI)Move quads and adjust BPM offsets for dispersion free trajectoryMove quads and adjust BPM offsets for dispersion free trajectoryIterateIterate……

RESULTRESULT: vary energy by factor of 3 : vary energy by factor of 3 ⇒⇒ trajectory changes by <10 trajectory changes by <10 μμmm

H. LoosH. Loos



First Lasing (April 10, 2009)First Lasing (April 10, 2009)

LCLS installed 12 undulator sections and a temporary YAG LCLS installed 12 undulator sections and a temporary YAG screen 50 m downstream (FEE not ready until June)screen 50 m downstream (FEE not ready until June)10 or 11 sections spontaneous (first and third 10 or 11 sections spontaneous (first and third harmonics) + FEL radiation (harmonics) + FEL radiation (IIpkpk = 500 A)= 500 A)

All 12 sections FEL radiation All 12 sections FEL radiation peak current (peak current (IIpkpk = 3000 A)= 3000 A)



Undulator Gain Length Measurement at 1.5 Undulator Gain Length Measurement at 1.5 ÅÅ

γεγεx,yx,y = 0.4 = 0.4 μμm (slice)m (slice)IIpkpk = 3.0 kA= 3.0 kAσσEE//EE = 0.01% (slice)= 0.01% (slice)

Recent Results!Recent Results!(25 of 33 undulators (25 of 33 undulators installed)installed)

LLGG ≈≈ 3.3 m3.3 m

1.5 1.5 ÅÅ FEL saturation observed: FEL saturation observed: April 14, 2009April 14, 2009 (after BBA)(after BBA)

Measurement is done by Measurement is done by kicking ekicking e--beam to disrupt beam to disrupt FEL along undulatorsFEL along undulators



FEL Energy (YAG)FEL Energy (YAG)

FELFEL--inducedinducedEnergy Loss (BPMs)Energy Loss (BPMs)

←← ~100 meters ~100 meters →→

4.6 MeV4.6 MeV

Pixel sum of xPixel sum of x--ray ray YAG screen CCD YAG screen CCD camera vs undulator camera vs undulator KK--tapertaper

4.6 MeV at 0.25 nC 4.6 MeV at 0.25 nC = 1.1 mJ or = 1.1 mJ or 0.80.8××10101212

photons/pulse (15 photons/pulse (15 GW at 75GW at 75--fs FWHM fs FWHM pulse length)pulse length)

1.5 1.5 ÅÅ

Dumpline Dumpline BPMsBPMs

Undulator Undulator ‘‘Taper ScanTaper Scan’’ Shows 1.1 Shows 1.1 mJmJ of Xof X--raysrays

DogDog--Leg Leg BPMsBPMs



YAGS2YAGS2

Laser Laser OFFOFFσσEE//EE << 12 keV12 keV

RF deflector RF deflector ONON

timetimeenergyenergy

Laser Heater Laser Heater Working WellWorking Welladds Landau dampingadds Landau damping

YAGS2YAGS2

Laser: Laser: 40 40 µµJJσσEE//EE ≈≈ 45 keV45 keV YAGS2YAGS2

Laser: Laser: 230 230 µµJJσσEE//EE ≈≈ 120 keV120 keV



Laser Heater Improves FEL Power

Laser heater OFFLaser heater OFF

Laser heater OFFLaser heater OFF

20 30 40 50 60 70

106

107

108

109

Active undulator length (m)

FEL

inte

nsity

(a. u

.)

Laser heater offLaser heater at 6.5 uJ

20 30 40 50 60 70

106

107

108

109


FEL

inte

nsity

(a. u

.)

Laser heater offLaser heater at 6.5 uJ

Laser Laser optimaloptimal

heater offheater offheater onheater on

FEL Gain:FEL Gain:

12 undulators inserted12 undulators inserted(FEL not saturated here)(FEL not saturated here)



XX--ray photon energy and bandwidthray photon energy and bandwidth

Use Ni KUse Ni K--edge (8.333 keV) before YAG to measure photon edge (8.333 keV) before YAG to measure photon energy and bandwidthenergy and bandwidthWith 12 undulatorsWith 12 undulators

With saturated FEL, Ni foil burns through in minutes With saturated FEL, Ni foil burns through in minutes estimated single pulse FEL energy: 300 estimated single pulse FEL energy: 300 μμJJ to 3 to 3 mJmJ

−0.8 −0.6 −0.4 −0.2 0 0.2 0.4 0.6 0.8

0

1

2

3

4

5

6

7

8

x 107

100*(c−d)/250 ()

YA

GS:

DM

P1:5

00:T

MIT

cha

rge

estim

ate

(Nel

)

Correlation Plot 11−Apr−2009 11:14:43

YAGS:DMP1:500:TMITerf(−(100*(c−d)/250+0.24)*6)*2.5e7+3.5e7

Error function fit yields Error function fit yields σσ=0.1% (FEL BW)=0.1% (FEL BW)

energy (%)



(D. Reis et. al.,)



PostPost--saturation Tapersaturation Taper

−6 −4 −2 0 2 4 6

x 10−3

−2

0

2

4

6

8

10

XCOR at Undulator 11 (kG−m)

FE

L−

indu

ced

ener

gy lo

ss (

MeV

)

Gain + Saturation taperGaussian fitGain taper onlyGaussian fit

1560 1580 1600 1620 1640 1660 16803.465

3.47

3.475

3.48

3.485

3.49

3.495

3.5

3.505

3.51

3.515

z [m]

K

09 10 11 12 1314 15 16

1718 19

2021 22

23

2425

26

27

28

29

30

31

32

33

> 8 MeV E> 8 MeV E--lossloss(> 2 (> 2 mJmJ xx--ray)ray)

Scan a corrector in beginning of Scan a corrector in beginning of Undulator to determine total EUndulator to determine total E--lossloss

FEL saturation power can be increased if undulator is tapered toFEL saturation power can be increased if undulator is tapered tostay in resonance with the decreasing electron energy stay in resonance with the decreasing electron energy

0 10 20 30 40 50 60 70 80 900

2

4

6

8

10

Ele

ctro

n en

ergy

los

s (M

eV)

Active undulator length (m)0 10 20 30 40 50 60 70 80 90

3.47

3.48

3.49

3.5

3.51

3.52

K

K E-loss

spontaneous+wakefieldspontaneous+wakefield



Preliminary 20 Preliminary 20 pCpC resultsresults

0 20 40 60 80104

106

108

1010


FEL

inte

nsity

(arb

. uni

ts)

20 PC FEL gain measurements (04/24/09) at 0.15 nm

BC2BC2(4.3 GeV)(4.3 GeV)

BSYBSY(14 GeV)(14 GeV)

TCAVTCAV(5.0 GeV)(5.0 GeV)

550 m550 mOTR22

4 wires4 wires

Integrate the bunch form factor over 1-2.5 μm from simulated particles at OTR22.

Photodiode (1-2.5 μm) signal collected from OTR22 (Results from last year)

Recent 20 Recent 20 pCpC FEL results at 1.5 FEL results at 1.5 ÅÅ

preliminarypreliminary

see Y. Ding’s talk



Future studiesFuture studies

FEL wavelength tuning: lased down to 1.5 nm with 1FEL wavelength tuning: lased down to 1.5 nm with 1--2 2 mJmJxx--ray energy, do not have sufficient diagnostics (need FEE) ray energy, do not have sufficient diagnostics (need FEE) Gain length dependence on Gain length dependence on IIpkpk & energy spread to & energy spread to understand our slice parametersunderstand our slice parametersGain length dependence on projected emittance, Gain length dependence on projected emittance, ββ--matching, different average beta in undulatormatching, different average beta in undulatorEmittance spoiling studies (using UV laser, OTR)Emittance spoiling studies (using UV laser, OTR)More taper study with 8 more undulatorsMore taper study with 8 more undulatorsLook for nonlinear third harmonic (in FEE?)Look for nonlinear third harmonic (in FEE?)BC2 overBC2 over--compression for chirped SASEcompression for chirped SASEMore extensive 20 More extensive 20 pCpC studiesstudiesOther charge configurations (1 Other charge configurations (1 nCnC, 100 , 100 pCpC, 10 , 10 pCpC……))



Summary

LCLS has lased spectacularly and reached FEL LCLS has lased spectacularly and reached FEL saturation at 1.5 saturation at 1.5 ÅÅ well within the designed well within the designed undulator lengthundulator length

These results demonstrate the practicality of 4These results demonstrate the practicality of 4thth

generation xgeneration x--ray FEL sourcesray FEL sources

Thanks LCLS commissioning team (particularly P. Thanks LCLS commissioning team (particularly P. Emma) for sharing these exciting results and slides!Emma) for sharing these exciting results and slides!

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