X

http://www.sciencemuseum.org.uk/Centenary.aspx

In a public poll by the Science Museum in London: what is the most significant scientific invention?

(1909-2009)

Bright xBright x--rayray sources from relativistic electronssources from relativistic electrons

Electrons emit with random phase radiation intensity N( is Lorentz factor, N is number of electrons ~109) Electrons emit with random phase radiation intensity N( is Lorentz factor, N is number of electrons ~109)

Synchrotron radiation Undulator radiation

• Produced by resonant interaction of a relativistic electron beam with EM radiation in an undulator

Free Free Electron Electron Laser (FEL)Laser (FEL)

electron electron beambeam

photon photon beambeam

ee beam beam dumpdumpundulatorundulator

1

• Radiation intensity N2

• Tunable, Powerful, Coherent radiation sources

Light Source Light Source Brightness (Brilliance)Brightness (Brilliance)

10 orders ofmagnitude!

Talk outlineTalk outline

IntroductionIntroduction

FEL physicsFEL physics

Ultrafast xUltrafast x--ray scienceray science

LCLS: the first hard xLCLS: the first hard x--ray laserray laser

Worldwide development and Future R&DWorldwide development and Future R&D

The The beginning…beginning…

John Madey, 1971

“…possibility of partially coherent radiation sources in the … x-ray regions to beyond 10 keV.”“…possibility of partially coherent radiation sources in the … x-ray regions to beyond 10 keV.”

Three FEL modesThree FEL modes

FEL oscillators(High-average power)

Single pass FELs (SASE or seeded)

zz

xx

Due to sustained interaction, some electrons lose energy, Due to sustained interaction, some electrons lose energy, while others gain while others gain energy modulation at energy modulation at 11

ee losing losing energy slow down, and energy slow down, and ee gaining energy catch up gaining energy catch up density modulation at density modulation at 11 ((microbunchingmicrobunching))

MicrobunchedMicrobunched beam radiates coherently at beam radiates coherently at 11, enhancing , enhancing the process the process exponential growth of radiation powerexponential growth of radiation power

uu

eeee11 xx--rayray

Electrons Electrons slipslip behind EM wave by behind EM wave by 11 per undulator period (per undulator period ( uu))++ ++ ++

++ ++ ++

KK//

vvxxEExx > 0> 0

++

ResonantResonantInteraction Interaction of of Field Field with with ElectronsElectrons

EE tt

EE tt

vvxxEExx > > 00 vvxxEExx > > 00vvxxEExx > 0> 0 vvxxEExx > > 00

FEL MicroFEL Micro--Bunching Along UndulatorBunching Along Undulator

S. ReicheS. Reicheloglog

(radiation (radiation power)power)

distancedistance

electron electron beambeam

photon photon beambeam

ee beam beam dumpdumpundulatorundulator

SASE FEL Electron Beam RequirementsSASE FEL Electron Beam Requirements

FEL grows exponentially with undulator distance z

peak current

only if beam energy spread << 10-3

power gain length

beam emittance

FEL power reaches saturation at ~ 20 LGSASE performance depends exponentially on e-

beam qualities

Why a Why a LinacLinac--Based FreeBased Free--Electron Electron Laser Laser ??

* * KondratenkoKondratenko, , SaldinSaldin 1980; 1980; BonifacioBonifacio, Pellegrini 1984, Pellegrini 1984

Use Use SASESASE* * (Self(Self--Amplified Spontaneous Emission) Amplified Spontaneous Emission) no mirrors or seed laser at 1 Å wavelengthsno mirrors or seed laser at 1 Å wavelengths

Longitudinal Longitudinal emittanceemittance from from linaclinac is ~10is ~1033 smaller than ringsmaller than ring

Bunch length can approach 100 Bunch length can approach 100 fsecfsec with small energy spreadwith small energy spread

Experience from linear collider operation and study (Experience from linear collider operation and study (SLCSLC,,TESLATESLA,, JLCJLC,, NLCNLC,, CLICCLIC,, ILCILC))

Electron bunch can be compressed to a few kA Electron bunch can be compressed to a few kA

Recent advances in highRecent advances in high--brightness RF photocathode gunsbrightness RF photocathode guns

OperationalUnder constructionProposed

OperationalUnder constructionProposed

SCSS-TA &XFEL/SPring-8

PAL XFEL

SDUV &SXFEL

LCLS &LCLS-II

DUV-FEL

SwissFEL

FERMI@ELETTRA

FLASH &European XFEL SPARC &

SPARX

Worldwide FELs

NGLS

WiFEL

Worldwide FELs

DUV FELSCSS-TA

SDUV-FELPolFELJLamp

FLASHFERMI@ELETTRA

SPARXSXFELLCLS-IIMAX IV

NGLS (LBNL)WiFEL

SwissFEL

LCLSXFEL/SPRing-8European XFEL

PAL XFEL

Era of XEra of X--ray Lasersray LasersProbe the Probe the ultrasmallultrasmall Capture the ultrafastCapture the ultrafast

nanoscale dynamics occursat femtosecond timescale

1 1 femtofemto--second (fs)second (fs) = = 1010 1515 secsec 0.3 0.3 mm

tt 1 sec1 sec

Time ScalesTime Scales

In Neils Bohr’s 1913 model of the Hydrogenatom it takes about 150 as for an electronto orbit the proton..–– NatureNature,, 20042004

100 100 femtofemto--second (fs) = second (fs) = 1010 1313 sec sec 30 30 mm

E. Muybridge and L. Stanford in 1878E. Muybridge and L. Stanford in 1878

E. Muybridge, E. Muybridge, Animals in MotionAnimals in Motion, ed. L. S. Brown (Dover Pub. Co., New York 1957)., ed. L. S. Brown (Dover Pub. Co., New York 1957).Muybridge used spark photography to freeze this ‘ultraMuybridge used spark photography to freeze this ‘ultra--fast’ processfast’ process

E. MuybridgeE. Muybridge

…they disagree whether all feet leave the ground during gallop……they disagree whether all feet leave the ground during gallop…

Understanding Understanding of a fast of a fast process by process by freezing the freezing the action…action…

L. StanfordL. Stanford

Coulomb Explosion of Lysozyme (50 fs)Coulomb Explosion of Lysozyme (50 fs)

JJ. . HajduHajdu,, Uppsala U.Uppsala U.

Atomic and Atomic and molecular molecular dynamics occur dynamics occur at the at the fsecfsec--scalescale

…which is being imaged …which is being imaged with intense with intense xx--rays rays BEFOREBEFORE its destructionits destruction

A Femto-Camera for Molecular Movies

molecules

optical laser

x-ray laser

before afterthe transition state

LLinac inac CCoherent oherent LLight ight SSource (ource (LCLSLCLS) ) at at SLACSLACLLinac inac CCoherent oherent LLight ight SSource (ource (LCLSLCLS) ) at 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)

XX--FEL based on last 1FEL based on last 1--km of existing 3km of existing 3--km linackm linacXX--FEL based on last 1FEL based on last 1--km of existing 3km of existing 3--km linackm linac

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

1.51.5--15 Å15 Å(14(14--4.3 GeV)4.3 GeV)

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

Proposed by C. Pellegrini in 1992

SLAC linac tunnelSLAC linac tunnel research yardresearch yard

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

LinacLinac--11L L 9 m9 mrf rf 2525°°

LinacLinac--22L L 330 m330 m

rf rf 4141°°

LinacLinac--33L L 550 m550 m

rf 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 MeVz z 0.83 mm0.83 mm

0.05 %0.05 %

135 MeV135 MeVz z 0.83 mm0.83 mm

0.10 %0.10 %

250 MeV250 MeVz z 0.19 mm0.19 mm

1.6 %1.6 %

4.30 GeV4.30 GeVz z 0.022 mm0.022 mm

0.71 %0.71 %

13.6 GeV13.6 GeVz z 0.022 mm0.022 mm

0.01 %0.01 %

LinacLinac--XXL L =0.6 m=0.6 mrfrf= =

21-1b,c,d

...existinglinac

rfrfgungun

21-3b24-6dX 25-1a

30-8c

undulatorundulator

beam parked here

beam parked here

Generation of low emittance beamPreservation of 6D brightness in accelerator/compressorUndulator tolerance and trajectory control

LCLS accelerator (commissioning started 2007)LCLS accelerator (commissioning started 2007)

Don’t underestimate 40+ years SLAC linac experience

132 meters of FEL 132 meters of FEL undulatorsundulators

Cavity BPM (<0.5 m)Cavity BPM (<0.5 m)QuadrupolemagnetQuadrupolemagnet

3.4-mundulatormagnet

3.4-mundulatormagnet

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

cam-based 5-DOF motion control –0.7 micron backlash

cam-based 5-DOF motion control –0.7 micron backlash

X-translation (in/out)

X-translation (in/out)

Wire Position MonitorWire Position Monitor

Hydraulic Level SystemHydraulic Level System

One of 33 One of 33 undulatorsundulators with controls with controls

First lasing and FEL saturation 1.5 First lasing and FEL saturation 1.5 ÅÅ

x,yx,y = 0.4 = 0.4 m (slice)m (slice)IIpkpk = 3.0 kA= 3.0 kA

EE//EE = 0.01% (slice)= 0.01% (slice)

((25 of 33 25 of 33 undulatorsundulatorsinstalled)installed)

LLGG 3.3 3.3 m (measured)m (measured)LLGG == 4.5 m (design)4.5 m (design)

First Lasing (April 10, 2009)First Lasing (April 10, 2009)FEL saturation observed: April 14, 2009

P. Emma et al., Nature Photonics 2010

LCLSLCLS AchievementsAchievements

Exceptional Exceptional ee beam quality from RF gun (beam quality from RF gun ( x,yx,y 0.4 0.4 mm))

Pulse length Pulse length easilyeasily adjustable for users (adjustable for users (60 60 -- 500 500 fs FWHM)fs FWHM)

LowLow--charge mode (20 charge mode (20 pCpC) allows <) allows <1010 fsfs pulses (~0.15 pulses (~0.15 mJmJ))

Wider photon energy range: Wider photon energy range: 480 480 -- 10000 10000 eV (design was: eV (design was:

830 830 -- 8300 eV)8300 eV)

Peak FEL power >Peak FEL power >7070 GW (10 GW in CDR)GW (10 GW in CDR)

Pulse energy up to Pulse energy up to 4 4 mJmJ (2 (2 mJmJ in CDR)in CDR)

96.796.7% accelerator availability, % accelerator availability, 94.894.8% photon availability% photon availability

120 120 fsfs pump probe synchronization has been achieved pump probe synchronization has been achieved

Far Experimental Hall

Near Experimental Hall

AMOSXRXPP

CXIXCSMEC

X-ray Transport Tunnel

200 mStart of

operation

Oct-09AMO

Fall-11XCSJune-11*CXI

October-10XPPMay-10SXR

MEC Fall-11

LCLS Experimental HallsLCLS Experimental Halls

Many high impact publications in Nature, PRL…

D. Wang et al., Science 324, 5931 (2009) •

A new paradigm opens up macromolecular structure determination to systems too small or radiation sensitive for synchrotron studies, and may save years of effort in crystallization trials

Single-shot diffraction patterns are recorded with 70 fs pulses. Coherent diffraction

shows the crystal size is sub-micron (top left) and that the crystal has a perfect lattice. Individual shots are oriented in 3D and

combined to build up the full information content of the underlying macromolecule (top right). This first demonstration was

carried out at 2 keV photon energy, limiting the resolution to about 9 Å. (This will be

improved with the dedicated CXI instrument.) The quality of the data are demonstrated by carrying out molecular

replacement refinement (right). Structural details such as helices can be observed.

• The ultrafast LCLS x-ray pulses allow us to record “diffraction before destruction”

where information is obtained before the onset of structural damage.

• Diffraction can be measured from sub-micron crystals containing less than a

thousand molecules.

• Demonstrated using Photosystem I, a membrane protein, key to

photosynthesis, that is extremely difficult to grow into large crystals.

• 30 single-crystal patterns per second were recorded from a liquid stream

carrying a suspension of nanocrystals. 15,000 of these were indexed and

combined into a full diffraction pattern which was analyzed with standard tools.

• Data are collected at room temperature. No cryogenic cooling or stabilization

required.

Linac Coherent Light Source H.N. Chapman et al., Nature 470, 73 (2011)

Femtosecond x-ray nanocrystallography overcomes limitations of radiation damage

Beyond crystallography: A new world in structural sciences

•A very short and extremely bright coherent X-ray pulse can be used to outrun key damage processes and obtain a single diffraction pattern from a large macromolecule, a virus, or a cell without the need for crystalline periodicity.

•Mimivirus is the largest known virus, comparable in size to a small living cell. It is too big for structure determination by electron microscopy and it cannot be crystallised.

•The structure of the intact virus was recovered from the flash diffraction pattern alone.

•There was no measurable sample deterioration. •Death-rays: We expect high-resolution structures in such experiments with shorter and brighter photon pulses focused to a smaller area.

•Resolution can be further extended by averaging for samples available in multiple identical copies.

Single mimivirus particles intercepted and imaged with an X-ray laser

1000 nm

1

1

0

0

a

c

b

f g

200 nm1

0

d e

200 nm

Linac Coherent Light Source D. Wang et al., Science 324, 5931 (2009) • Linac Coherent Light Source M.M. Seibert, T. Ekeberg, F.R.N.C Maia et al., Nature 470, 78–81 (2011)

LCLS has experienced rapid user growth LCLS has experienced rapid user growth that is now limited by capacitythat is now limited by capacity

Oct.2009 May 2010 Oct.2010 May 2011

314 proposals 314 proposals submitted to date (through 2010)

1094 unique scientists 1094 unique scientists from from 25 countries 25 countries listed as collaborators on proposals submitted Sept 2008-June 2010

359 on359 on--site users site users worked at LCLS on scheduled proposals in FY2010

one in four proposals is approved due to capacity limits

LCLSLCLS--IIII

present LCLS

LCLS-2025

LCLS II (CD-1 2011, CD-4 2018)

soft x-rayhard x-ray

SLAC’s vision

soft x-rayhard x-ray

LCLS 2025

European XFEL ~ 2015

FLASH and European XFELFLASH and European XFEL

SINAP Photon Science Center

Compact XFELSXFEL

FEL R&Ds

• Higher peak power• Higher average power• Precise synchronize with lasers• Control x-ray polarization state• Produce attosecond x-ray pulses• …

• SASE FELs have excellent transverse coherence but lack full temporal coherence (due to shot noise startup)

• Temporal coherence can be drastically improved by seeding (external or self seeding)

SASE

seeded

HighHigh--Gain Harmonic Generation (HGHG)Gain Harmonic Generation (HGHG)

DDModulatorModulator RadiatorRadiator

11 hh== 11/h/h

seed seed laserlaser

to next to next stagestage

……...……...electronselectrons

L.L.--H. Yu, PRA44, 5178 (1991)H. Yu, PRA44, 5178 (1991)

Echo-Enabled Harmonic Generation (EEHG)G. Stupakov, PRL 102, 074801 (2009)

Separated energy bands Separated current spikesOne optical cycle

Very high harmonic bunching may be produced from external laserDemonstration experiments at SLAC and SINAP look promisingHigh harmonic bunching may seed a soft x-ray FELs (a few nm wavelength)

SDUV-FEL

HGHG Saturation (2010.12)

Courtesy Z. Zhao, D. Wang

EEHG Results (2011.04)

330 335 340 345 350 355 3600.0

0.2

0.4

0.6

0.8

1.0

inte

nsity

(a.u

.)

wavelength (nm)

HGHG co-exist EEHG

0 5 10100

1000

10000

100000

1000000

1E7

pow

er (W

)z (m)

HGHG (Genesis) EEHG (Genesis) HGHG (experimental) EEHG (experimental)

Courtesy Z. Zhao, D. Wang

Power dist. after Power dist. after diamond crystaldiamond crystal

Monochromatic Monochromatic seed powerseed power

6 6 mm

Hard XHard X--ray Selfray Self--Seeding @ LCLS Seeding @ LCLS SelfSelf--seeding of 1seeding of 1-- m m ee pulse at 1.5 Å yields pulse at 1.5 Å yields 1010 44 BWBW with 20with 20--pC pC mode. mode. UndulatorUndulator taper provides taper provides 3030 brightness & 25 GWbrightness & 25 GW..PP. Emma (. Emma (SLAC), ASLAC), A. Zholents (ANL). Zholents (ANL)

FEL spectrum after the diamond crystal

Geloni, Kocharyan, Saldin (DESY)

1 GW1 GW ~25 GW~25 GW

WideWide--band band powerpower

Seeded FEL simulation (J. Wu)

LCLSLCLS--II II undulatorundulator

8.3 8.3 keVkeV ---- 1.5 Å 1.5 Å (13.5 (13.5 GeV)GeV)Quadratic tapering starts at Quadratic tapering starts at 20 20 m m (8.5%) (8.5%) from from 20 20 m to m to 200 200 mm4040--pC pC bunch bunch charge, 10 charge, 10 fsfs FWHM FWHM 0.20.2-- m m emittanceemittance

~1 ~1 TTWW

1.0 x 10 4

FWHMBW

J. Wu (SLAC)J. Wu (SLAC)

Seeding+Tapered Undulator TW FEL

Seeding start

Driven by development of accelerator science and technology, fourth-generation x-ray source based on FEL mechanism has become a reality

ConclusionsConclusions

X-ray FELs are opening up a new world of ultrasmall and ultrafast.

The high demands from the x-ray community will drive continuous growth of such sources and R&Ds.