a laser driven linear accelerator: byerpanel on light source facilities, national science foundation...

Panel on Light Source Facilities, National Science Foundation Wednesday 9 January 2008 Lawrence Livermore National Laboratory

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Robert L. Byer, Tomas Pletter, Eric Colby, Ben Cowan, Chris Sears, Jim Spencer and Robert Siemann

Department of Applied PhysicsSLAC

Stanford [email protected]

ABSTRACT

In 1947 W. W. Hansen and colleagues accelerated electrons with microwaves generated from a Klystron.That work led to the 3km linear accelerator at the Stanford Linear Accelerator Center completed in 1968.

In November 2005 we successfully accelerated electrons with a visible modelocked laser source. Today we are conducting experiments at SLAC to develop photonic bandgap dielectric based accelerator structures to efficiently couple laser radiation to electrons. The dielectric structures allow laser accelerators to operate at accelerating gradients of 1GeV/meter.

We have explored the possibility of laser accelerator driven coherent X-rays using a free electron laser. The approach looks promising because of the replacement of the traditional magnet based undulator with a laser driven dielectric based undulator. Progress toward the accelerator and coherent X-ray source will be discussed.

Panel on Light Source FacilitiesNational Science Foundation

Lawrence Livermore National LaboratoryWednesday 9 January 2008

A Laser Driven Linear Accelerator:A Pathway Toward Attosecond Coherent X-rays


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Contents

Historic BackgroundThe Klystron and the Linear Acceleration of electronsStanford Linear Accelerator Center – SLAC

The TeV-Energy Physics Frontier

Laser Electron Accelerator Project – LEAPHEPL Experiments from 1997 – Nov 2004E163 Experiments at SLAC

Laser accelerator structuresInverse FEL for electron pulse compression - <1 fsec electron pulse duration

Coherent X-ray laser GenerationComponents of the X-ray laser

Dielectric Accelerator and Undulator StructuresFEL gain and efficiency

Future ChallengesToward Table top Synchrotron sources

“Don’t undertake a project unless it is manifestly important and nearly impossible.” Edwin Land – 1982


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The development of the linear accelerator at Stanford University

“we have accelerated electrons”

1947: The Mark I, 1m, 6 MeV

The Mark III

1953: 400 MeV1955: 600 MeV1960: 1 GeV

Hansen's report to the Office of Naval Research

Meson Physics carried out by W. K.H. Panofsky

High resolution electron scattering from nuclei by Robert Hofstadter

A high-energy physics research tool

U E dr= ⋅∫r r


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The “Microwave” Lab (Now HEPL and Ginzton Labs) played a crucial

role on the development of particle accelerators and the

corresponding RF technology

The Klystron tube

Ed GinztonW. W. Hansen – back rightMarvin Chodorow & Klystron


ByerGroupSLAC: The two-mile accelerator

• $100M proposal• numerous studies and reports • > 10 years of effort

“Project M”1955 first brainstorming and informal discussions

First beam at SLAC, 1966


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Particle accelerator research at Stanford

6

1st Klystron (Varian, 1930s’) 1st Linac 1946

The superconducting linacIn HEPL, 1960

Demonstration of the FEL, 1977

The 2-mile collider (SLAC)

LEAP, 1997-2004


ByerGroupSLAC – Particle Physics, Astrophysics

& Photon Science

1968: First evidence of Quarks1974: Discovery of the ψ particle1976: Discovery of the charm quark

and the τ lepton 1997: The BaBar experiment2006: LINAC coherent X-ray source

Other developments• SSRL user facility• Computer science, software• KIPAC Particle Astrophysics


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The Livingston plot – 1954Innovation leads to exponential progress

In 1954 Livingston noted that progress in high energy accelerators was exponential with time.

Progress was marked by saturation of the current technology followed by the adoption of innovative new approaches to particle acceleration.

Laser sources coupled with related technologies enable new approaches to Advanced Electron Accelerators.


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Contents

Historic Background



Laser accelerator structuresInverse FEL for electron pulse compression



Future ChallengesToward Table top Synchrotron Sources


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proton beams

What is next?

Future TeV e+e- collision experiments

• Top Quark Physics

• Higgs Boson Searches and Properties

• Supersymmetry

• Anomalous Gauge Boson Couplings

• Strong WW Scattering

• New Gauge Bosons and Exotic Particles

• e-e-, e-γ, and γγ interactions

• Precision Tests of QCD

The NLC ZDR Design Group and the NLC Physics Working GroupsSnowmass `96 workshop

historical trend of high energyphysics experiments

discovery of theatomic nucleus

discovery of the neutron

discovery of the muon

discovery of pions

first artificialantiproton production

discovery of the J/ψ

particle

discovery of the τparticle

discovery of the Υparticle

CP violationExperiment

BaBar

confirmation of the Z,W

particles

electron-nucleusscattering

experiments1 MeV

1 GeV

1 TeV

year

radioactive sources, cosmic raysproton beamselectron beams

1910 1920 1930 1940 1950 1960 1970 198 0 1990 2000

discovery of theatomic nucleus

discovery of the neutron

discovery of the muon

discovery of pions

first artificialantiproton production

discovery of the J/ψ

particle

discovery of the τparticle

discovery of the Υparticle

CP violationExperiment

BaBar

confirmation of the Z,W

particles

discovery of the

top quark

discovery of the

top quark

electron-nucleusscattering

experiments1 MeV

1 GeV

1 TeV

year

colli

sion

ene

rgy

radioactive sources, cosmic rays

electron beams

1910 1920 1930 1940 1950 1960 1970 198 0 1990 2000

CERNLHC


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33 km

3 km

Existing and Proposed Linear Accelerators

Existing SLAC – 50 GeV Proposed ILC Accelerator 1 TeV

The goal of the Laser Electron Accelerator Program – LEAP - is to invent a new approach that will allow TeV physics on the SLAC site.

To achieve the goal we need an acceleration gradient of 1 GeV per meter.


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Laser-driven particle acceleration

IntroductionIntroduction

• Idea came about soon after the invention of high-peak power lasers (earliest articles go back to 1971)

• different laser particle acceleration conceptsponderomotivelinear electric fieldinverse cherenkovinverse FELactive gain mediumlaser driven plasma wakefield…

• very controversial topic

• experimental demonstrations are fairly “recent”


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Laser Driven Plasma Wakefield Acceleration


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Principle of the Wakefield Accelerator


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Wakefield Accelerator as a Booster for SLAC


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Linear accelerators - accelerating relativistic electrons

1974 –sabbatical leave, Lund 1994 – SLAC summer school 2004 – Successful 1st Exp

electron source

DC potential RF modulator(buncher)

pre-accelerator accelerator structures

0 eV 100 keV ~ 2 MeVMeV/m 50≤

∆∆

xU

0=β 21~β 1→β

A few rules of the game

“An accelerator is just a transformer” – Pief Panofsky“All accelerators operate at the damage limit” - Pief

“To be efficient, the accelerator must operate in reverse”- Ron Ruth, SLAC

“ It is not possible to accelerate electrons in a vacuum”Lawson - Woodward theorem

“An accelerator requires structured matter – a waveguide -to efficiently couple the field to the electrons” anon


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Emergence of new technologies make Laser Acceleration Possible

NUFERN

ALABAMA LASER

high powerfiber lasers

ultrafast laser technology

nanotechnology

60 W/bar, 50% electr. efficiency

efficient pump diode lasers

< 10 fsIMRA mJ 500

fsec laser

new materials

high strength magnets

New ceramicsNd:Fe

nano-tubes

high purity optical materials and high strength coatings

17

sodium yellow

Leveraging investment in

telecom

30 W/bundle, 40% electr. efficiency


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cavity length,dispersion control

modelocked laser

accelerator cell array

amplifier


amplifier


amplifier

mode converter


modelocked laser


amplifier


amplifier


amplifier

mode converter


modelocked laser


amplifier


amplifier


amplifier

mode converter


modelocked laser


amplifier


amplifier


amplifier

mode converter

Master oscillator electron beam

referencebeam

Proposed layout of the lasersystem for a TeV collider

A low-power ultra-stable master oscillator serves as a reference clock for the entire accelerator

local modelocked oscillators are phase-locked to the master oscillator

A mode converter transforms the TEM00 mode preferred by the laser to a TEM01 acceleration mode

Laser amplifiers increase the power of the TEM01 mode from sub-watt to multiple tens of watts of average power mode

Schematic of Future TeV scale Laser Accelerator


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2. Low bunch chargeproblem

• Take advantage of high laserrepetition rate

• Multiple accelerator array architecture

Laser pulse structure that leads to high electron bunch repetition rate

10 laser pulsesper laser pulse

train

104 laser pulse trains per second

laser pulselaser pulse train

laser pulse

optical cycle

electron bunch

10 laser pulsesper laser pulse

train

104 laser pulse trains per second

laser pulselaser pulse train

laser pulse

optical cycle

electron bunch

SLC NLC SCA-FEL TESLA laser- accelerator

2.856 11.424 1.3 1.3 3×104

120 120 10 4 10 4

1 95 10 4 4886 10

- 2.8 84.7 176 3×10-6

1.2×102 1.1×104 1×105 1.6×104 3×106

3.5×1010 8×109 3.1×107 1.4×1010 10 4

4×1012 9×1013 3×1012 2×1019 3×1010

mf

bN

RFf

bt∆

eN

bf

(Hz)

(nsec)

(GHz)

(Hz)

eI (sec-1)

SLC NLC SCA-FEL TESLA laser- accelerator

2.856 11.424 1.3 1.3 3×104

120 120 10 4 10 4

1 95 10 4 4886 10

- 2.8 84.7 176 3×10-6

1.2×102 1.1×104 1×105 1.6×104 3×106

3.5×1010 8×109 3.1×107 1.4×1010 10 4

4×1012 9×1013 3×1012 2×1019 3×1010

mf

bN

RFf

bt∆

eN

bf

(Hz)

(nsec)

(GHz)

(Hz)

eI (sec-1)

Dramatic increase of •electric field cycle frequency•macro pulse repetition rate

Laser beam parameters for TeV scale accelerator

Requires 10kW/meter or 10MW/km at ~40% efficiency Laser Source!


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fsec 5 m, 5.1 == τµλ

attosec 14 nm, 15

=∆=∆

tx

1 degree of optical phase

laser beam

electronbunch

~104 e-/bunch

Atto Second Electron Bunches


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Contents

Historic Background






Future Challenges


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FWH

M e

nerg

y sp

read

(keV

)

laser timing (psec)

FWH

M e

nerg

y sp

read

(keV

)

laser timing (psec)

laser on

laser off

Laser driven particle acceleration

collaborators

ARDB, SLACBob Siemann*, Bob Noble†, Eric Colby†, Jim Spencer†, Rasmus

Ischebeck†, Melissa Lincoln‡, Ben Cowan‡, Chris Sears‡, D. Walz†, D.T. Palmer†, Neil Na‡, C.D Barnes‡, M Javanmarad‡, X.E. Lin†

Stanford UniversityBob Byer*, T.I. Smith*, Y.C. Huang*, T. Plettner†, P. Lu‡, J.A. Wisdom‡

ARDA, SLACZhiu Zhang†, Sami Tantawi†

Techion Israeli Institute of TechnologyLevi Schächter*

UCLAJ. Rosenzweig*

‡ grad students † postdocs and staff * faculty

Laser Electron Accelerator Project - LEAP


ByerGroupParticipants in the LEAP Experiment

1 E.L. Ginzton Laboratories, Stanford University2 Stanford Linear Accelerator Center (SLAC)3 Department of Physics, Stanford University

Bob Byer1

Bob Siemann2 Chris Sears2 Jim Spencer2

Tomas Plettner1 Eric Colby2

Ben Cowan2

•Chris Mcguinness2

•Melissa Lincoln2

•Patrick Lu1

•Mark Kasevich3

•Peter Hommelhoff3

•Catherine Kealhofer3

Atomic Physics collaboration

New students


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Laser acceleration – Dielectric structure means high acceleration gradient

Energy gain through longitudinal electric field• gradient = longitudinal electric field• linear e-beam trajectory

no synchrotron radiationenergy scalable

Dielectric based structure with vacuum channel

very high peak electric fields

Inherent attosecelectron pulse

2 µm laser 6 fsec period 1deg of phase = 20 attosec

Unique opportunity for light sources

linear particle acceleration

process

11

22

33λ ~ 2 µm, T~ 6.6 fsec

T~ 20 attosec1° of optical phase

electric field

electron bunch

λ ~ 2 µm, T~ 6.6 fsec

T~ 20 attosec1° of optical phase

electric field

electron bunch

∆U E dzz= ⋅∫

vacuum channel

NIR solid-state lasers

metals

Es → 1010 V m

Gradient GeV m→ 1


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LEAParea

kickercollimator

slitsFEL

wigglersuperconducting

accelerator structures

amplified laserBeam Energy ~30 MeVTelectron ~2 psecCharge per bunch ~5 pCEnergy spread ~20 keVλlaser 800 nmElaser 1 mJ/pulse

HEPL beam parameters

The proof-of-principle experiment

electronbeam

materialboundary

θ

electronbeam

Ez

8 µm Kapton 1 µm Au

laserbeam

∆U E dzz=−∞∫0


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electronbeam

laserbeam

8 µm thick gold-coated Kapton tape

stepper motors

acceleratingphase

deceleratingphase

laserbeamelectron

beam

InverseFEL

tape drive

LEAP Experimental Success- November 2004

The simplified single stageAccelerator cell that uses gold coated Kapton tape to terminate the Electric field.

The LEAP experimental apparatus thatIncludes the LEAP single stage acceleratorcell and the inverse FEL.

We have accelerated electrons with visible light!


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Tomas Plettner and LEAP Accelerator Cell

The key was to operate the cell above damage threshold to generateenergy modulation in excess of the noise level.


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FWH

M e

nerg

y sp

read

(keV

)

laser timing (psec)

FWH

M e

nerg

y sp

read

(keV

)

laser timing (psec)

laser on

laser off

• confirmation of the Lawson-Woodward Theorem

• observation of the linear dependence of energy gain with laser electric field

• observation of the expected polarization dependence

E dzz−∞

+∞

∫ = 0

∆U Elaser∝

E Ez laser∝ cosρ

laser-driven linear

acceleration in vacuum

Accelerated electrons – key experimental results

Laser Polarization Angle θ (degrees)

Ave

rage

Ene

rgy

Mod

ulat

ion

⟨M⟩(

keV

)

Laser Polarization Angle θ (degrees)

Ave

rage

Ene

rgy

Mod

ulat

ion

⟨M⟩(

keV

)

Peak Longitudinal Electric Field Ez (MV/m)

0.1 0.2 0.3 0.4Laser Pulse Energy (mJ/pulse)

0.05

Ave

rage

Ene

rgy

Mod

ulat

ion

⟨M⟩(

keV

)

( ) ( )25.035.0017.0349.0 ±−⋅±= zEM

modelM simulation

M data

zEM ⋅= 361.0model

Peak Longitudinal Electric Field Ez (MV/m)

0.1 0.2 0.3 0.4Laser Pulse Energy (mJ/pulse)

0.05

Ave

rage

Ene

rgy

Mod

ulat

ion

⟨M⟩(

keV

)

( ) ( )25.035.0017.0349.0 ±−⋅±= zEM

modelM simulation

M data

zEM ⋅= 361.0model


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Laser peak electric field (GVolt/m)

Ave

rage

mod

ulat

ion

stre

ngth

(keV

)

Energy Modulation vs Laser Peak Electric Field

18 72 162 284 448

0

2

4

6

8

10

12

14

16

0 0.5 1 1.5 2 2.5

Laser pulse energy (µJ)

3.92.51.40.60.2

Laser fluence (J/cm2)

m 100psec 0.4Tnm 800

FWHM

FWHM

µ

λ

=Α==

The acceleration is linearwith the applied laser fieldas expected from theory.

(This is a modest laser with ~200 micro Joules in 4psec)


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2nd Success: Visible light driven IFEL

30

* graduate student C.M. Sears

Cross-correlation in time Observation of harmonic interaction

AARD subpanel Dec 21, 2005


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Contents

Historic Background






Future Challenges


ByerGroupThe E163 experiment at SLAC

The new E163 experiment hall - 2005

The NLCTANext Linear Collider Test Accelerator 360MeV


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60 MeV10 pC~ 1psec

λ = 800 nmU ~ ½ mJ/pulseτ ~ 200 fsec


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GOAL: Invent and Test Accelerator structures

34

R. Ischebeck, R. J. Noble, B.Cowan*, M. Lincoln*,C. Sears*

Photonic bandgap fiber structures 2 and 3-D photonic bandgap structures

Planar waveguide structures

*grad. students

Current experimental fiber accelerator structure research


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Goal: Develop Theory for laser accelerator physics

35

Beam loading calculations vs N Coupling Efficiency vs bunch charge

N (Number of bunches)

Energy efficiency of laser accelerators, single and multiple bunch operation

optimum efficiencyabout 1 fC


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Hollow core PBG fibers 3-D photonic bandgap structures

B. M. Cowan, Phys. Rev. ST Accel. Beams , 6, 101301 (2003).X.E. Lin, Phys. Rev. ST Accel. Beams 4, 051301 (2001)

Z. Zhang et al. Phys. Rev. ST AB 8, 071302 (2005)

xyz

laserbeam

cylindrical lensvacuum

channel

electron beam

cylindrical lens

top view

λ/2

λ

xyz

laserbeam


channel

electron beam

cylindrical lens

top view

λ/2

λ

top view

λ/2

λ

Periodic phase modulation structures

T. Plettner et al, Phys. Rev. ST Accel. Beams 4, 051301 (2006)

Many possible dielectric microstructure architectures

Planar waveguide structures


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Transverse pumped grating phase-reset structure

T. Plettner et al, Phys. Rev. ST Accel. Beams 4, 051301 (2006)

Main concept: quasi phase-matching of the EM field

λ/2

λ

λ/2

λ

λ/2

λ

λ/2

λ

λ/2

λ

λ/2

λ

e

e

0=t

2lasert τ

=xy

z

perspective view

dielectric structure

vacuum channel

laser beam

electron beam

top viewtraveling electron experiences accelerating force at all times


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||E

dielectric structure

electron beam

vacuum channel

input laser wavefront

EM field map in one unit

0=⊥Fr

laserEE 21

|| ~r

Transverse pumped phase-reset structure

vacuum channel width < λ

1 J/cm2 fluence

~10 fsec pulses

GeV/m 4~unloadedG


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U V

y

x

z

U V

pλ

a) b)

0

1

2

l

laserwall EE

wdielectric

dielectric

vacuum

laser beam

electron bunch U V

y

x

z y

x

z

U V

pλ

a) b)

0

1

2

l

laserwall EE

wdielectric

dielectric

vacuum

laser beam

electron bunch

The expected maximum gradientsOperate at the Breakdown Limit

max, 07.0~ EG TE⊥

r

GV/m 4~||,TEG

max||, 15.0~ EG TE

r

GV/m 25~maxE

laserTE EG 15.0~,⊥

r

laserTE EG 3.0~||,

r

2÷

10 10 fsecfsec laser pulselaser pulse

1 J/cm2

Y. Min Oh et al, International Journal of Heat and Mass Transfer 49 (2006) 1493–1500B. C. Stuart et al, Physical Review Letters 74, 2248 (1995) M. Lenzner et al, “Femtosecond Optical Breakdown in Dielectrics”, Phys. Rev. Lett. 80, 4076 (1998)

GV/m 2~,TEG⊥(At breakdown limit)


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10-4

10-3

10-2

10-1

100

10-2

10-1

100

101

102

1 102 10310 0.1

102

101

10-1

10-2

100

bunch charge (fC)

dece

lera

tion

grad

ient

(G

eV/m

)

0xbq

pλ

a) b)

1SP

2SP

10-4

10-3

10-2

10-1

100

10-2

10-1

100

101

102

1 102 10310 0.1

102

101

10-1

10-2

100

bunch charge (fC)

dece

lera

tion

grad

ient

(G

eV/m

)10

-410

-310

-210

-110

010

-2

10-1

100

101

102

1 102 10310 0.1

102

101

10-1

10-2

100

bunch charge (fC)

dece

lera

tion

grad

ient

(G

eV/m

)

0xbq

pλ

a) b)

1SP

2SP

The most simplistic wakefield pictureThe accelerator operates in reverse

Assume a “perfect” dielectric (real index of refraction)The loss factor mechanisms come from diffraction

[1] Phys. Rev. Lett. 74, 3808 (1995)[2] Phys. Rev. STAB 6 02441 (2003) [3] Phys. Rev. STAB 9, 111301 (2006)[4] Phys. Rev. STAB 7, 061303 (2004)

γλπ 1~4 0 pxfwd. Smith-Purcell [1]

( )( ) LWLL EEEZ

DLqV τ22

02+−=beam loading [2,3,4]

GV/m 4~||,TEG

40 fC

GeV/m/pC 100~CK

but I have neglected the broadband Cherenkov wake…

GeV/m/pC 100~CK

fC 20~bQ


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focusing triplet

2 cm 1 mm

electron beam60 MeV

laser beam

to the energy spectrometer

fabricated by graduate student C.M. Sears

fabricated by graduate student P.P. Lu

Transverse pumped phase-reset structure Goal: test this structure at SLAC

a) b)a) b)


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optical buncher

compressor chicane

laser PMT

400 nm filter

800 nm

Present experiment at E163

Micro-bunching of a 60 MeV electron beam at 800 nm from a 3-period IFEL

(Principal author: Chris Sears)


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Present experiment at E163Preliminary results provided by Chris Sears


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optical buncher compressor

chicane

laser PMT

400 nm filter

800 nm

PMT

Near-future experiment at E163

400 nm filter

quartz grating

pellicle

Observation of wakefields of the microbunched beam from a quartz gratingBeam position diagnosticInverse process of laser acceleration from the grating


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Laser-acceleration from a quartz-based mm-long accelerator microstructure

focusing triplet

2 cm 1 mm

electron beam60 MeV

laser beam



fabricated by graduate student P.P. Lua) b)a) b)


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focusing triplet

electron beam60 MeV

beam splitter

laser beam

phase delay


Cascading of microstructure accelerators

Future ExperimentsGoal: test multiple stage acceleration

Show scalabilityShow scalability


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Contents

Historic Background






Future Challenges


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SSRL

undulator

3 km

120 m

accelerator

Experiment lines

LCLSinjector

T ~ 230 1 fsecλ ~ 1.5 – 15 ÅΦ ~ 1012 γ / pulse

SASE-FEL 14 GeV

• materials science• chemistry• atomic physics

100 m

T ~ 230 1 fsecλ ~ 1.5 – 15 ÅΦ ~ 1012 γ / pulse

SASE-FEL 14 GeV

• materials science• chemistry• atomic physics

100 m

Coherent picosecond X-ray wavelength sourcesLINAC Coherent Light Source – at SLAC

• km-size facility• microwave accelerator• λRF ~ 10 cm• 4-14 GeV e-beam

• 120 m undulator• 23 cm period• 15-1.5 A radiation• 0.8-8 keV photons• 1014 photons/sec• ~77 fsec

• separate user lines• 120 Hz pulse train

LCLS propertiesLCLS properties

TTF: Tesla Test Facility; fsec EUV SASE FEL facilityXFEL: Proposed future coherent X-ray source in Europe…TTF: Tesla Test Facility; fsec EUV SASE FEL facilityXFEL: Proposed future coherent X-ray source in Europe…

RFRF--accelerator driven SASE FEL facilities accelerator driven SASE FEL facilities -- 20092009


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source of free particles

accelerator section

undulator

The Key Components of the SASE-FEL architectureSASE – Self Amplified Spontaneous Emission

dielectric structure, laser driven

dielectric structurebased laser-driven

particle accelerators

SSRL

undulator

3 km

120 m

accelerator

Experiment lines

LCLSinjector

SSRL

undulator

3 km

120 m

accelerator

Experiment lines

LCLSinjector

laser-drivenhigh rep. ratevery compact


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Motivation for an FEL applicationAttosecond Physics at hard X-ray energies

~ 1 GeV/m gradient GeV electron beam in 1-2 m

Few-attosec pulse structure

Possibility for MHz rep. rate

Short undulator preserve the few-attosec pulse structure on the photons

Modelocked lasers and low-power amplifiers

Suitable electron injectorSuitable electron injector

Matching short undulatorMatching short undulatorRequirements:Requirements:


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Source of free particles

Accelerator section

undulator

Architecture of a laser-driven free-electron X-ray source

λλ ~ 1 ~ 1 µµmm

• sub-kW of electrical power• no radiation or electrical hazards• MHz repetition rates

solid state, solid state, tabletoptabletop

laser systemlaser system

Laser-driven field emission sources

MEMs-based laser-driven dielectric

accelerator structure

MEMs-based laser-driven dielectric

deflection structure

x-rays

ultra short pulseshigh peak electric fields

total length on the order 1 mtotal length on the order 1 m

optically bunched electrons


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accelerator section

undulator

Development of the three key laser-driven components

Objective:Objective:

develop a compact laser-driven electron injector

1. High rep. rate2. Low power consumption3. Ultra low emittance (~10-9 m-rad)4. ~10 MeV in a few-cm structure


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The klystron• ~2 m tall• 1/3 MV !• high power• water cooling• X-ray radiation• 10 Hz rep. rate

A conventional electron injector

temporary source of relativistic electrons for present laser-acceleration

experiments

RF cathode

a room full of lethal and bulky equipment…

The NLCTA accelerator front end


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field emitter tip

Field emission tip propertiesField emission tip properties1. laser-assisted tunneling of electrons

from the atom to free space2. Highly nonlinear

3. Potential for timed sub-optical cycle electron emission

metal vacuum

e

P. Hommelhoff et al, Kasevich group

laser beam

A laser-driven field-emission free-electron source

P. Hommelhoff, Y. Sortais, A. Aghajani-Talesh, M. A. Kasevich, “Field Emission Tip as a Nanometer Source of Free Electron Femtosecond Pulses”, PRL 96, 077401 (2006)

radm 10~ 10 −−tipε


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Laser

field emitter tip

Electrostatic lens

GND

Accelerator cell

grid

MCP

10 fsec

1. multiple-electron emission2. focusing with electrostatic lens3. verify ultra-low emittance4. verify ~700 attosec bunch5. modulate energy

objectivesobjectives

Addition of a low-energy laser-accelerator cell

graduate student

Anthony Serpry

Collaboration work with the Kasevich group

J.W. Lewellen, J. Noonan, “Field-emission cathode gating for rf electron guns”, Phys. Rev. ST AB 8 033502 (2005)

Concept of field-emission arrays:


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accelerator section

undulator



develop MEMs based laser-driven accelerator structures

1. Dielectric optical MEMs structures2. High acceleration gradients (~ 1 GeV/m)3. Mono-energetic, maintenance of low emittance


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Proposed parameters for laser driven SASE–FEL

Laser accelerator undulator

~ 2 m

~ 1 GeV

Input electron beam Input electron beam ~ 1-2 GeV beam energy~ 10 10 attosecattosec pulse durationpulse duration~ 1 pC bunch charge~ 0.05% energy spread

undulatorundulatorλu ~ 200 µmLu ~ 20-40 cmB0 ~ ½ - 1 T

( )

−=′

∂∂

∆∆∈

−∑ vetzEt j

i jψχ2,~

Field envelope growthField envelope growth

electrons per unit volume

Smallest possible

beam size

φb < 500 nm

Solid state laser

λ ~ 1 µm

3 fsec10 attosecpulse structure

λ


ByerGroup


accelerator section

undulator


First Idea:First Idea:

Periodic Magnetic UndulatorField strength ~ 1 TeslaModulation Period ~ 0.1mmLength ~ 30cm


ByerGroupAttosecond X-ray FEL Source – First Approach

59

ε ~ 10-9 m-radqb ~ 1 fC

LG ~ 1 cmLsat ~ 30 cm

LFODO ~ 1 cmoxy ~ 3 µm

frep ~ 1 MHzηacc ~ 1% Pacc ~ 10 W laser powerηlaser ~ 10 % wallplug efficiencyPe ~ 100 W electrical power

1% of Ub = 10-7 J U ~ 107 Photons

~ 1 nJ/pulse

50 60 70 80 90 100 110 120 130 140 1500.5

1

1.5

2

2.5

3

3.5

4

4.5

5

5.5

be a m e ne rgy (Me V)

wav

e;en

gth

(nm

)

E = 100 MeVq = 6250 e/bunch (1 fC)λu = 100 µmDe = 3 µm

50 60 70 80 90 100 110 120 130 140 1500.5

1

1.5

2

2.5

3

3.5

4

4.5

5

5.5

be a m e ne rgy (Me V)

wav

e;en

gth

(nm

)

E = 100 MeVq = 6250 e/bunch (1 fC)λu = 100 µmDe = 3 µm

1

2

3

4

5

wav

elen

gth

(nm

)

60 80 100 120 140

beam energy (MeV)

λu ~ 100 µmλr ~ 1 nm

0 0.5 1 1.5 2 2.5 30

2

4

6

8

10

12

electron beam size (microns)

leng

th (

mm

)

leng

th (m

m)

2

6

10

1 2 3

electron beam size (µm)

LG

LRL LR G>

E = 100 MeVq = 1 fC /bunchλu = 100 µm

0 0.5 1 1.5 2 2.5 30

50

100

150

200

250

300

350

400

450

500

electron beam size (microns)

ener

gy s

prea

d (k

eV)

EE ρσ ≤

100

200

300

400

1 2 3

electron beam size (µm)

ener

gy s

prea

d (k

eV)

10-3

10-2

10-1

100

101

102

10-4

10-3

10-2

10-1

100

101

beam energy (GeV)

min

imum

FE

L w

avel

engt

h (n

m)

70 Å

100 MeV

ε ~10-3 µm-rad

λu ~ 28 µm

πλε4

r≤

0.1 1 100.01

beam energy (GeV)

min

,. FE

L w

avel

engt

h (n

m)

1

10

0.1

0.01

1-D FEL modelDesign parameters must satisfy these conditions

Starting point

λb ~ 18 attosecUb ~ 10-7 J

~ 30 cm~ 1 cm ~ 3 µmUndulator

design

Laser power required

1% conversion efficiency


ByerGroup


accelerator section

undulator


KEY IDEA: Use fsec laser to Drive Dielectric Undulator


develop MEMs based laser-driven deflection structures

1. Dielectric optical MEMs structures2. High gradients (~ 1 GeV/m)3. Possibility for compact undulators


ByerGroup

accelerator structure deflection structure

( ) 0=×+ ⊥⊥ BvErrr ( ) 0≠×+ ⊥⊥ BvE

rrr

GeV/m 4~ ~ 21

|| →laserEEr GeV/m 2 ~ ~ 5

1 →⊥ laserEqFr

T. Plettner, “Phase-synchronicity conditions from pulse-front tilted laser beams on one-dimensional periodic structures and proposed laser-driven deflection”, submitted to Phys. Rev. ST AB

keykey ideaideaextended phase-synchronicity between the EM field and the particle

The structure geometry determines the force component


ByerGroup

pλ

yz

x

pλ6.0

pλ4.0

58.1=n

a) b)

0 50 100 150 200-0.25

-0.2

-0.15

-0.1

-0.05

0

0.05

0.1

0.15

0.2

0.25

0 50 100 150 200-0.4

-0.3

-0.2

-0.1

0

0.1

0.2

0.3

0.4

0.0

0.2

0.4

-0.2

-0.4

norm

aliz

ed g

radi

ent

optical phase (φ)

+π0−π

0.0

0.2

-0.2

norm

aliz

ed g

radi

ent

optical phase (φ)

+π0−πTE polarization TM polarization

yG ′||,

zG ′⊥,

xG ′⊥,

zG ′⊥,yG ′||,

0.1

-0.1

xG ′⊥,

c) d)

z′ˆ

x′ˆ y′ˆparticle

trajectory

xG ′⊥, yG ′||,

zG ′⊥,total,⊥G

incoming wave

θpλ

yz

x

yz

x

pλ6.0

pλ4.0

58.1=n

a) b)

0 50 100 150 200-0.25

-0.2

-0.15

-0.1

-0.05

0

0.05

0.1

0.15

0.2

0.25

0 50 100 150 200-0.4

-0.3

-0.2

-0.1

0

0.1

0.2

0.3

0.4

0.0

0.2

0.4

-0.2

-0.4

norm

aliz

ed g

radi

ent

0.0

0.2

0.4

-0.2

-0.4

norm

aliz

ed g

radi

ent

optical phase (φ)

+π0−π

0.0

0.2

-0.2

norm

aliz

ed g

radi

ent

optical phase (φ)

+π0−πTE polarization TM polarization

yG ′||,

zG ′⊥,

xG ′⊥,

zG ′⊥,yG ′||,

0.1

-0.1

xG ′⊥,

c) d)

z′ˆ

x′ˆ y′ˆparticle

trajectory

xG ′⊥, yG ′||,

zG ′⊥,total,⊥G

incoming wave

θ

The expected phase-synchronous force components


ByerGroup

uλundulator period uλundulator period

pulse-front tilted laser

beams

deflection structure sections

uλundulator period uλundulator period uλundulator period uλundulator period


beams


A dielectric structure undulator

• same loss factorsame loss factor as the laser accelerator: ~100 GV/m/pC• similar structure geometrysimilar structure geometry fabrication compatibility


ByerGroup

-6 -4 -2 0 2 4 60

2

4

6

8

10

12

14

16

18

20

-6 -4 -2 0 2 4 6 8 100

10

20

30

40

50

60

100 200 300 400 500 600 700 800 90010

1

102

103

104

105

106

-10 -5 0 5 10 15 200

10

20

30

40

50

60

70

80

-10 -5 0 5 10 15 20

-6 -4 -2 0 2 4 6 -6 -4 -2 0 2 4 6 8 10

200 400 600 800

1.0

2.0

3.0

4.0

5.0

6.0

7.0

8.0

0.20.40.60.81.01.21.41.61.82.0

1.0

2.0

3.0

4.0

5.0

6.0

101

102

103

104

105

106

time (attosec)

time (attosec)

time (attosec)

undulator periodnu

mbe

r of p

hoto

ns

pow

er (G

W)

pow

er (G

W)

pow

er (G

W)

a) b)

c) d)

-6 -4 -2 0 2 4 60

2

4

6

8

10

12

14

16

18

20

-6 -4 -2 0 2 4 6 8 100

10

20

30

40

50

60

100 200 300 400 500 600 700 800 90010

1

102

103

104

105

106

-10 -5 0 5 10 15 200

10

20

30

40

50

60

70

80

-10 -5 0 5 10 15 20

-6 -4 -2 0 2 4 6 -6 -4 -2 0 2 4 6 8 10

200 400 600 800

1.0

2.0

3.0

4.0

5.0

6.0

7.0

8.0

0.20.40.60.81.01.21.41.61.82.0

1.0

2.0

3.0

4.0

5.0

6.0

101

102

103

104

105

106

time (attosec)

time (attosec)

time (attosec)

undulator periodnu

mbe

r of p

hoto

ns

pow

er (G

W)

pow

er (G

W)

pow

er (G

W)

a) b)

c) d)

rcL λ21~

rb λσ 136~

6~cb Lσ

( )brsGG NLL σλ 31~ 0 +4105~ −×= beamFELeff UUρ

0.13 mm 3.0

cm 4

nm 200 0.1%

fC 20 rad-m 10

attosec 5 GeV 2

*

9b

===

==∆==

==

−

K

Q

U

u

r

b

N

b

λβ

σγγ

ε

τ

simulation parametersexpected temporal

profile at 12 cmexpected temporal

profile at 15 cm

expected temporal profile at 27 cm

pulse fluence vs. undulator length

short pulse regime

1D model of Attosecond 120keV FEL


ByerGroupExperiments to be conducted at SLAC

laser on

focusing triplet

2 cm 1 mm

electron beam60 MeV

laser beam

laser off(no deflection)

Test of laser-deflection Structure

Prove the concept of a phase-synchronous deflection forceProve the concept of a phase-synchronous deflection force


ByerGroup

60 MeVelectron beam

deflector structure

1 mm

90 degree spectrometer

magnet

Ce:YAGscintillator

screen

45° pulse-front tilted laser

beam

PI MAX camera

discarded electrons

filtered electron beam

energy

verti

cal

dim

ensi

on

laser offlaser on

Near-future experiment at E163Measure Deflection of the Delectric Laser Driven Undulator


ByerGroupExperiments to be conducted at SLAC

pulse-front tilted laser beam



electron beam

mask or high-reflector

undulator radiation




electron beam

mask or high-reflector

undulator radiation

Look for undulator radiation

Prove the concept Prove the concept

measure

uur

u

u

N

NK

λλθ

ωωλ

2

1

=∆

=∆∝

( ) ( ) ( )

+−

++= 22

2

022

2

122

2

21421421 KKJ

KKJ

KKNph πα

mm 1=uλ

4103~ ×phN

nm 40~rλ


ByerGroup

Contents

Historic Background






Future Challenges

Table Top Synchrotron Source

“Don’t undertake a project unless it is manifestly important and nearly impossible.” Edwin Land – 1982


ByerGroup

0 5 10 15 20 25 30 35 40 45 500

0.5

1

1.5

2

2.5

3

3.5

4

energy (MeV)

bend

ing

radi

us (

cm)

GV/m 3.1~qF⊥

⊥

=F

mcr22βγ

Bending radius from a deflector structure

A first step towards a Laser Accelerator driven Table Top Synchrotron X-ray Source

{Bending radius ~ 1m for 1GeV electron source}


ByerGroupSummary

Dielectric structure FEL• injector• accelerator• undulator

Laser-driven

1. photon energy of tens of keV 2. ~105 photons/pulse3. 80 MHz 1012 photons/sec

properties

initial work• laser-particle accelerators (LEAP/E163)• field-emission injector• modeling of the undulator and FEL process

future• dielectric structure accelerators• test a laser-driven deflector• construct a low-energy pre-accelerator


ByerGroupLong-term experiments

Inject higher density of optically bunched electrons into the structuresearch for small-signal gainverify predicted beam loading and wakefield effects

Test other materials for dielectric structuresverify index of refraction and transparency windowperform laser-damage threshold testsradiation damage tests

Integration of the componentscascading of ~103 mm-long accelerator sectionscascading of ~102 sub-mm long deflection sectionsbeam transport: steering and periodic focusingbeam diagnostics: BPMs, etc

Refinement of the ideaundulator optimization: periodic focusing, tapering, etc.seeding, resonator configurationharmonic generation


ByerGroup

This work is supported by1. accelerator work: supported by DOE DE-FG06-97ER41276 2. light-source application: supported by Northrop Grumman

Acknowledgements

1. R. Ischebeck, E. Colby, R. Siemann, C.M. Sears, S. Fan, and Z. Huang

2. P. Hommelhoff and M. Kasevich for guidance on field-emission tips

3. H. Injeyan and R. Rice for discussing possible applications of the proposed X-ray sources

4. The NLCTA personnel at SLAC for guidance on operating the test accelerator


ByerGroup

Anthony Serpry

Catherine Kealhofer

Peter Hommelhoff

Mark KasevichPatrick Lu,K-Xun Sun

Y.C. HuangT.I. SmithH. Wiedemann

RasmusIschebeck

Ben Cowan

Jim Spencer

Chris McGuinness

Bob Siemann

Eric Colby

Bob Byer

Tomas plettner

Chris Barnes

Chris Sears

Bob NobleDieter Walz

past collaborators

Relativistic electron laser-acceleration group

Low-energy electron laser acceleration group


ByerGroupSelected publications

74

1. Y.C. Huang, D. Zheng, W.M. Tulloch, R.L. Byer, “Proposed structure for a crossed-laser beam GeV per meter gradient vacuum electron linear accelerator”, Applied Physics Letters, 68, no. 6, p 753-755 (1996)

2. Y.C. Huang, T. Plettner, R.L. Byer, R.H. Pantell, R.L. Swent, T.I. Smith, J.E. Spencer, R.H. Siemann, H. Wiedemann, “The physics experiment for a laser-driven electron accelerator”, Nuclear Instruments & Methods in Physics Research A 407 p 316-321 (1998)

3. X. Eddie Lin, “Photonic band gap fiber accelerator”, Phys. Rev. ST Accel. Beams 4, 051301 (2001)

4. E. Colby, G. Lum, T. Plettner, J. Spencer, “Gamma Radiation Studies on Optical Materials”, IEEE Trans. Nucl. Sci. Vol. 49, No. 6, p. 2857-2867 (2002)

5. B. M. Cowan, “Two-dimensional photonic crystal accelerator structures”, Phys. Rev. ST Accel. Beams 6 101301 (2003)

6. R.H. Siemann, “Energy efficiency of laser driven, structure based accelerators”, Phys. Rev. ST AB. 7 061303 (2004)

7. T. Plettner, R. L. Byer, R. H. Siemann, “The impact of Einstein’s theory of special relativity on particle accelerators”, J. Phys. B: At. Mol. Opt. Phys. 38 S741–S752 (2005)

8. Y. C. Neil Na, R. H. Siemann, R.L. Byer, “Energy efficiency of an intracavity coupled, laser-driven linear accelerator pumped by an external laser”, Phys. Rev. ST. AB. 8, 031301 (2005)

9. T. Plettner, R.L. Byer, E. Colby, B. Cowan, C.M.S. Sears, J. E. Spencer, R.H. Siemann, “Visible-laser acceleration of relativistic electrons in a semi-infinite vacuum”, Phys. Rev. Lett. 95, 134801 (2005)

10. C.M.S. Sears, E. Colby, B. Cowan, J. E. Spencer, R.H. Siemann, T. Plettner, R.L. Byer, “High Harmonic Inverse Free Electron Laser Interaction at 800 nm”, Phys. Rev. Lett. 95, 194801 (2005)

11. T. Plettner, R.L. Byer, E. Colby, B. Cowan, C.M.S. Sears, J. E. Spencer, R.H. Siemann, “Proof-of-principle experiment for laser-driven acceleration of relativistic electrons in a semi-infinite vacuum”, Phys. Rev. ST Accel. Beams 8, 121301 (2005)

AARD subpanel Dec 21, 2005


ByerGroup

The Livingston curveW. K. H. Panofsky, SLAC Beamline, 1997

1. near-exponential growth in the beam energy up until about 1990

2. LHC and future NLC/ILC lie below the exponential growth curve

3. Exponential curve important for new physics

For future high energy colliderfacilities beyond the LHC and ILC it becomes increasingly appealing to invest in new accelerator technologies

RF based accelerator technology is nearing its

practical high-energy limit

Future Maximum gradient ~ 1000 MeV/m


ByerGroup

• BACK UP SLIDES


ByerGroup

Proposed parameters for laser driven SASE–FEL

oscillator laser

field emission

tip

laser accelerator

amplifiers

low energy high energy

undulator

beam dump

2 m ½ m

xyz

laserbeam


channel

electron beam

cylindrical lens

top view

λ/2

λ

xyz

laserbeam


channel

electron beam

cylindrical lens

top view

λ/2

λ

top view

λ/2

λ

~200 µm

~50 µm

~ 40 cm

~200 µm

~50 µm

~ 40 cm

1 pC, 2 GeV, λu = 200 µm,Lu = 40 cmrb ~ 200 nmB ~ 1 T


ByerGroup

0 500 1000 1500 2000 2500 3000-9

-8

-7

-6

-5

-4

-3

-2

-1

0

1x 10

-5

0 10 20 30 40 50 60 70 80 90 1000

2

4

6

8

10

12

14x 10

9

time (attosec)

pow

er (

W)

0 500 1000 1500 2000 2500 30000

1

2

3

4

5

6x 10

28

1 pC, 2 GeV, λu = 200 µm,3000 periodsrb ~ 200 nmB ~ 1 T

Photon field buildupPhoton field buildupm

illion

s of

pho

tons

Time profile of Time profile of SASE FEL pulsesSASE FEL pulses

Pow

er (G

W)

0 20 40 60undulator position (cm)

6x106 photons1 photon/electron10 GW peak power~15 attosec FWHM~20 attosec timing jitterEγ~ 190 kev

6x106x1066 photonsphotons1 photon/electron1 photon/electron10 GW peak power10 GW peak power~15 ~15 attosecattosec FWHMFWHM~20 ~20 attosecattosec timing jittertiming jitterEEγγ~ 190 ~ 190 kevkev

Loss of kinetic energyLoss of kinetic energy


ByerGroup

Laser damage and radiation damage studies

1

10

100

1000

2 2.1 2.2 2.3 2.4 2.5 2.6 2.7

borofloat, air, chamber

fluence (J/cm 2)

0

0.5

1

1.5

2

2.5

CaF2 borofloat fused silica sapphire MgF2 HR coating LiNbO3

air vacuum

fluen

ce(J

/cm

2 )

air vacuumCaF2 2.212 2.260borofloat 2.064 2.054fused silica 2.027 1.795sapphire 1.574 1.152MgF2 1.455 1.455800 nm HR 0.769 0.768LiNbO3 0.504 0.194

materialdamage threshold

undamaged sample

damaged sample

Laser damage threshold studiesRadiation damage studies


ByerGroup

Laser research

-45-40-35-30-25-20-15-10

-505

950 1000 1050 1100 1150

Wavelength (nm)

Pow

er (d

Bc)

Original PulseBroadened Pulse 1Broadened Pulse 2Broadened Pulse 3


ByerGroup

The SCA-FEL facility

81

LEAParea

kickercollimator

slitsFEL

wigglersuperconducting

accelerator structures

amplified laserBeam Energy ~30 MeVTelectron ~2 psecCharge per bunch ~5 pCEnergy spread ~20 keVλlaser 800 nmElaser 1 mJ/pulse

SCA beam parameters

Commercial, tabletop amplified sub-psecmJ/pulse laser sources

The SCA Accelerator provided a source of 30MeV electrons for LEAP


ByerGroup

Laser acceleration concept

82

Pantell, 1979

Magnitude Phase

Gouy PhasePlane Wave Phase Math

( )

( ) ( ) 01

222

233

22

22ˆ

2/3220

cosˆtan2cosˆ1tancosˆ

cos

coscosˆ1sin

exp)cosˆ1(

sin2

φθθθθθωθψ

ψθθ

θθ θ

+⋅−+

⋅+⋅−⋅⋅=

×

+−

+−=

− zz

ztzk

zzEE

dt

t

z

zd

†P. Sprangle, E. Esarey, J. Krall, A. Ting, Laser Accelerationof Electrons in Vacuum, Optics Comm. 124 (1996) 69

E1

E2

E1z

E2z

E1x

E2x

z

x

( ) ( ) zdzEzUz

zz ′′= ∫

0

conceptual idea

laser beamdielectricmaterial

electronbeam

( ) 00

>′′∫ zdzEd

z

z

laser in laser out

dielectric waveguide structure

vacuum channel

accelerating force

electron bunch

∆U E dzz= ⋅∫boundary


ByerGroup

Laser ONLaser OFF

Observed energy profiles

Laser ONLaser OFF


Laser ONLaser OFF


0 20 40- 40 - 20

0.2

0.4

0.6

0.8

1.0

Energy spread (keV)

Nor

mal

ized

cha

rge

per u

nit e

nerg

y Laser ONLaser OFF


Laser ONLaser OFF


Laser ONLaser OFF


0 20 40- 40 - 20

0.2

0.4

0.6

0.8

1.0

Energy spread (keV)

Nor

mal

ized

cha

rge

per u

nit e

nerg

y

The LEAP experiment(Laser Electron Accelerator Project)

83

electronbeam

laserbeam

8 µm thick gold-coated Kapton tape

stepper motors

spectrometer

The field-terminating boundary

camera

0 ½π−π -½πoptical phase of the laser

elec

tron

ener

gy+∆

Um

ax−∆

Um

ax

broadening of the initial

energy spread of the electron

beam accelerating

phase

deceleratingphase

E dzz ⋅ >−∞∫0

0


ByerGroup

“New” technology: the laser

60 W/bar50% now 78%electrical efficiency

Stuart, et. al,, Phys Rev. Lett. Vol 74, No 12 p. 2248 (1995)

damage threshold of dielectric materials

high power solid state lasers

modelocked laser technology

NUFERN ALABAMA LASER

high power fiber lasers

10 GV/m fields for 100 fseclaser pulses


ByerGroupNear-future experiment at E163

Laser-acceleration from a quartz-based mm-long accelerator microstructure

focusing triplet

2 cm 1 mm

electron beam60 MeV

laser beam



fabricated by graduate student P.P. Lua) b)a) b)


ByerGroup

accelerator structure deflection structure

( ) 0=×+ ⊥⊥ BvErrr ( ) 0≠×+ ⊥⊥ BvE

rrr

GeV/m 4~ ~ 21

|| →laserEEr GeV/m 2 ~ ~ 5

1 →⊥ laserEqFr

key ideakey ideaextended phase-synchronicity between the EM field and the particle

The concept of a laser-driven particle deflection micro-structure


ByerGroup

60 MeVelectron beam

deflector structure

1 mm

90 degree spectrometer

magnet

Ce:YAGscintillator

screen

45° pulse-front tilted laser

beam

PI MAX camera

discarded electrons

filtered electron beam

energy

verti

cal

dim

ensi

on

laser offlaser on



ByerGroup

uλundulator period uλundulator period


beams


uλundulator period uλundulator period uλundulator period uλundulator period


beams


A dielectric structure undulator

• same loss factorsame loss factor as the laser accelerator: ~100 GV/m/pC• similar structure geometrysimilar structure geometry fabrication compatibility


ByerGroup

-6 -4 -2 0 2 4 60

2

4

6

8

10

12

14

16

18

20

-6 -4 -2 0 2 4 6 8 100

10

20

30

40

50

60

100 200 300 400 500 600 700 800 90010

1

102

103

104

105

106

-10 -5 0 5 10 15 200

10

20

30

40

50

60

70

80

-10 -5 0 5 10 15 20

-6 -4 -2 0 2 4 6 -6 -4 -2 0 2 4 6 8 10

200 400 600 800

1.0

2.0

3.0

4.0

5.0

6.0

7.0

8.0

0.20.40.60.81.01.21.41.61.82.0

1.0

2.0

3.0

4.0

5.0

6.0

101

102

103

104

105

106

time (attosec)

time (attosec)

time (attosec)

undulator periodnu

mbe

r of p

hoto

ns

pow

er (G

W)

pow

er (G

W)

pow

er (G

W)

a) b)

c) d)

-6 -4 -2 0 2 4 60

2

4

6

8

10

12

14

16

18

20

-6 -4 -2 0 2 4 6 8 100

10

20

30

40

50

60

100 200 300 400 500 600 700 800 90010

1

102

103

104

105

106

-10 -5 0 5 10 15 200

10

20

30

40

50

60

70

80

-10 -5 0 5 10 15 20

-6 -4 -2 0 2 4 6 -6 -4 -2 0 2 4 6 8 10

200 400 600 800

1.0

2.0

3.0

4.0

5.0

6.0

7.0

8.0

0.20.40.60.81.01.21.41.61.82.0

1.0

2.0

3.0

4.0

5.0

6.0

101

102

103

104

105

106

time (attosec)

time (attosec)

time (attosec)

undulator periodnu

mbe

r of p

hoto

ns

pow

er (G

W)

pow

er (G

W)

pow

er (G

W)

a) b)

c) d)

rcL λ21~

rb λσ 136~

6~cb Lσ

( )brsGG NLL σλ 31~ 0 +4105~ −×= beamFELeff UUρ

0.13 mm 3.0

cm 4

nm 200 0.1%

fC 20 rad-m 10

attosec 5 GeV 2

*

9b

===

==∆==

==

−

K

Q

U

u

r

b

N

b

λβ

σγγ

ε

τ

simulation parametersexpected temporal

profile at 12 cmexpected temporal

profile at 15 cm

expected temporal profile at 27 cm

pulse fluence vs. undulator length

short pulse regime

Calculated 120 KEV X-ray FEL Performance


ByerGroup

Linear accelerators - accelerating relativistic electrons

Schematic of a linear accelerator

electron source

DC potential RF modulator(buncher)

pre-accelerator accelerator structures

0 eV 100 keV ~ 2 MeVMeV/m 50≤

∆∆

xU

0=β 21~β 1→β

elec

tron

rela

tive

vel

ocity

v/c

electron kinetic energy

100 keV 1 MeV 100 MeV 10 GeV 1 TeVSuperconducting Accelerator


ByerGroup

Dream: Table Top Attosecond X-ray FEL Source

91

attosec light sources 1° of optical phase at 2 µm 20 attosec

Table Top attosec x-ray source with medical and chemistry applications

N

S N

S N

S N

S N

S N

S N

S N

S

N

S N

S N

S N

S N

S N

S N

S N

S

N

S N

SN

S N

S N

S N

SN

S N

S N

S N

SN

S N

S N

S N

SN

S N

S

N

S N

SN

S N

S N

S N

SN

S N

S N

S N

SN

S N

S N

S N

SN

S N

S

low energy 100 MeVe-beam

Preliminary model studies• 1st initial feasibility study with the 1D FEL model• Attosec bunching of 1fC helps enhance the gain• “low” 1 MHz rep. rate low avg. power • Further more refined studies under way• It deserves a closer look

Take advantage of ultra-low emittance laser-accelerator e-beam and new magnetic materials

1m

110 VProf. Byer’s dream…

20 asecHigh strength Nd:Femicromagnets

The wizard of optics

a laser driven linear accelerator: byerpanel on light source facilities, national science foundation...

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