l o a victor malka loa, ensta – cnrs - École polytechnique, 91761 palaiseau cedex, france...
TRANSCRIPT
L O A
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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