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Victor Malka

LOA, ENSTA – CNRS - École Polytechnique,91761 Palaiseau cedex, France

COULOMB05, Senagolia, Italy, September 12-16 (2005)

State of Art of Laser-Plasma Accelerators

Laser beam

Electron beam

1 mm Laser beam

proton beam

1 m

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Particle group

F. EwaldJ. FaureY. GlinecA. LifschitzJ.J. Santos

Laser group

F. BurgyB. MercierJ.Ph. Rousseau

A. Pukhov, University of Dusseldorf, Germany

ELFSPL

Collaborators

E. Lefebvre, CEA/DAM Ile-de-France, France

Supported by EEC under FP6 : CARE

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E-field max ≈ few 10 MeV /meter (Breakdown) R>Rmin Synchrotron radiation

Classical accelerator limitations

LEP at CERN

27 km

Circle road

31 km

New medium : the plasma

Energy = Length = $$$

≈ PARIS

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Why is a Plasma useful ?

• Plasma is an Ionized Medium High Electric Fields

epz nE ~~w

• Superconducting RF-Cavities : Ez = 55 MV/m

ez nE ~

Are Relativistic Plasma waves efficient ?Ez = 0.3 GV/m for 1 % Density Perturbation at 1017

cc-1

Ez = 300 GV/m for 100 % Density Perturbation at 1019 cc-1

L O ATajima&Dawson, PRL79

How to excite Relativistic Plasma waves?

The laser wake field

laser≈ Tp / 2=>Short laser pulse

Laser pulse

F≈-grad I

Electron density perturbation

Phase velocity vepw=vglaser => close to c

Analogy with a boat

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FF≈-grad I

Train of short resonant pulsesLaser envelop modulation

k

k2

How to excite Relativistic Plasma waves?

(ii) The laser beat waves

1-2 = p

Linear growth : d(t)=1/4a1a2wpt

=>Homogenous plasmasSaturation : relativistic,

ion motion

Optical demonstration by Thomson scattering :

Clayton et al. PRL 1985,Amiranoff et al. PRL 1992,, Dangor et al. Phys. Scrypta 1990

Chen, Introduction to plasma physics and controlled fusion, 2nd Edition, Vol.1, (1984)

Motivations

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electron

Analogy:

t1 t2 t3

e >> >> 1

=> Emax(MeV)=( n/n)(nc/ne)

=>Ldeph.=(0/2)(nc /n e)3/2

Emax=2(n/n) 2mc2

L Deph. =p2

Analogy electron/surfer Motivations

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Motivations

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Few MeV gain

Laser

Injected electronsFew MeV

Injected electrons acceleration with laser :

Wake field , Beat wave

Motivations

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Electron Acceleration : LBWFElectron spectra indicate an Efield of ≈ 0.7 GV/m

= 100 , e = 6 , laser = 40 µm , e = 40 µm , divergence = 10 mrad

Ele

ctr

on

s

nu

mb

er

exp

eri

men

t

0

100

200

300

400

500

600

0

500

1000

1500

2000

3,3 3,4 3,5 3,6 3,7 3,8 3,9

Th

eory

Energy (MeV)

d = 1,6%

LULI/LPNHE/LPGP/LSI/IC

Electron gain demonstration Few MeV’s:Kitagawa et al. PRL 1992,Clayton et al. PRL 1993,N. A. Ebrahim et al.,

J. Appl. Phys.1994, Amiranoff et al. PRL 1995

Motivations

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How to generate an electron beam?

Self-modulated Laser Wakefield Scheme (Andreev, Sprangle, Mora 1992)

cp

enhances

WavebreakingPc(GW) = 17 02/p

2

Short Pulse Energetic Electronsif then

excites

Modena et al., Nature 1995

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Wave breaking : from waves to particles

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Relativistic wave breaking

Ele

ctro

ns/

MeV

detector limit

105

106

104

103

101

102

0 20 40 60 80 100 120

Energy (MeV)

ne=0.5x1019cm-3

ne=1.5x1019cm-3

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Review of some Former Experiments on

Lab Year Process EL Rate Ee

RAL 1995* SMLWF 50 J 20 min 44 MeV

1998 SMLWF 50 J 20 min 100 MeV

NRL 1997 SMLWF 5 J 5 min 30 MeV

MPQ 1999 DLA 0.2 J 10 Hz 10 MeV

LOA 1999 SMLWF 0.6 J 10 Hz 70 MeV

LOA 2001 FLWF 1 J 10 Hz 200 MeV

Electron Beam Generation

Large scale, energetic laser, with low repetition rate

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5-pass Amp. : 200 mJ

8-pass pre-Amp. : 2 mJ

Oscillator : 2 nJ, 15 fs

Stretcher : 500 pJ, 400 ps

After Compression :1 J, 30 fs, 0.8 m,

10 Hz, 10 -7

2 m

Nd:YAG : 10 J

4-pass, Cryo. cooled Amp. :< 3.5 J, 400 ps

Salle Jaune Laser

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10

100

1019 1020E

max (

MeV

)n

e (cm -3)

Emax=4p2mec

2dnn

Tunable electron beam : temperature

Electrons are accelerated by epw

V. Malka et al., PoP (2001)

F/6

106

107

108

109

1010

0 10 20 30 40 50 60 70

# e

lect

rons/

MeV

/sr

W (MeV)

Teff=8.1 MeV

Teff=2.6MeV

detection threshold

Ne=1.5x1019cm-3

Ne=1.5x1020cm-3

INCREASE THE ACCELERATION LENGTH

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Interaction chamber (inside)

Laser beam

electron beam

50 cm

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Summary of FLWF previous results

V. Malka et al., Science, 298, 1596 (2002)

105

106

107

108

109

1010

0 50 100 150 200Energy (MeV)

Detection Threshold

Nu

mb

er

of

ele

ctr

on

(/M

eV

/sr)

Experiments

106

107

108

109

1010

1011

0 50 100 150 200 250Energy (MeV)N

um

ber

of

ele

ctr

on

(/M

eV

/sr)

3D PIC simulations

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Low Normalized Emittance

Emittance is indeed comparable with todays Accelerators

Electron Energy (MeV)

n (

mm

mra

d)

20 40 60

20

40

Ee- = ~ 55 MeV = ~ 3 mm mradn

x (mm)

x

(mra

d)

-

Ee- = ~ 20 MeV

= ~ 32 mm mraden

0.5 -0.25 0 0.25 0.5

-0.05

0

0.05

S. Fritzler et al., PRL 04

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SMLWF : Multiple e- bunches / FLWF Single e- bunch

Electron bunches

laser

Electric field

Ps

V. Malka, Europhysics news, April 2004Ps/fs

Electron bunch

laserElectron density perturbation

ne/n0-1

Electric field

0

fs

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700

650

Z/

20

-20

Y/

-20

2 0

X/

Quasi-Monoenergetic Electron Beams

In homogenous plasma : virtual or real?

0 200 400 E, MeV

t=350

t=450

t=550

t=650

t=750

t=850

5 108

1 109Ne / MeV

Time evolution of electron spectrum

monoenergeticelectron beam

VLPL

A.Pukhov & J.Meyer-ter-Vehn, Appl. Phys. B, 74, p.355 (2002)

One stage LPA

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Experimental Setup : single shot measurement

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2.0 x 1019cm-3

Divergence = 6 mrad

Recent results on e-beam :Spatial quality improvements

6.0 x 1018cm-37.5 x 1018cm-31.0 x 1019cm-3

5.0 x 1019cm-3 3.0 x 1019cm-3

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Recent results on e-beam :From Mono to maxwellian spectra

Electron density scan

V. Malka, et al., PoP 2005

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Charge in [150-190] MeV : (500 ±200) pC

Energy distribution improvements:The Bubble regime

PIC

Experiment

Divergence = 6 mrad

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S. Mangles et al., C. Geddes et al., J. Faure et al., in Nature 30 septembre 2004

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Some Applications ...

X-rays:diffractionmedicine

-rays:radiography

MedicineRadiotherapy Proton-therapy

PET

Accelerator Physics

Chemistry

Radiolysis

Electrons and Protonsgenerated byLaser-PlasmaInteractions

+X ray LarmorX ray laser

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GeV acceleration in two-stages

GeV

Laser Plasma channel

•50-150 TW•~50 fs

Nozzle

Gas-JetLaser

•170±20 MeV•30 fs•10 mrad

•1 J•10 TW•30 fs

•Pulse guiding condition : Δn>1/πre rc2

•Weak nonlinear effects more control : a0 ~ 1-2

•High quality beams : Lb <λp n0<1018 cm-3

rc

Δnn0

Density profile

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GeV in low plasma density in plasma channel

n0=8 1016 cm-3, 11 J - 140 TW rc=40 μm, Δn=2 n0

L channel=4 cm 8 cm

12 cm

4

2

3

1

00 800400 1200

dN

/dE

(a.u

.)

Energy (MeV)Electron bunch

Electric field

Electron bunch

Electric field

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On the ultra short duration benefitfs radiolysis :

H2O (e-s, OH., H2O2, H3O+, H2, H.) e-

Very important for:• Biology• Ionising radiations effects

B. Brozek-Pluska et al., Radiation and Chemistry, 72, 149-159 (2005)**Ar.

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In collaboration with L. Le-Dain, S. Darbon from CEA Mourainvilier and DAM

Material science: -ray radiography

High resolution radiography of dense object with a low divergence, point-like electron source

Glinec et al., PRL 94 p025003 (2005)

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-radiography results

A-A' cut

20mm

Cut of the object in 3D

• Spherical hollow object in

tungsten with sinusoidal

structures etched on the

inner part.

Measured Calculated

Source size estimation : 450 um

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Medical application : Radiotherapy

VHE ELECTRONS

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Dose deposition profile in water

Glinec et al., accepted in Med. Phys.

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Laser plasma acceleration has demonstrated•Energy gains of 1 MeV to 200 MeV•E-fields of 1 GV/m to 1000 GV/m•Good e-beam quality : Emittance < 3mm.mrad

•charge at high energy•Quasi monoenergetic• Very high peak current : 100 kA

Laser plasma accelerators advantages Provide e-beam with new parameters : shortProvide e-beam with new parameters : high currentProvide e-beam with new parameters : CollimatedCompact and low cost

The laser plasma accelerators status

ゝゝ

ゝゝ

ゝゝ

ゝゝ

ゝゝ

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Laser plasma accelerator:

• enhance stability•electron sources up to ≈ 1 GeV (nC, <1 ps): Guiding or PW class laser systems Single Stage (Pukhov, Mori) (200TW)

•Generate a tunable e-beam• applications of these electron sources •Compact XFEL

Perspectives

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A revolution is coming…one of the most evolving field in Science, a wonderful tool for academic formation

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