Resultats récents sur l’accélération d’ions : optimisation de faisceau et applications
description
Transcript of Resultats récents sur l’accélération d’ions : optimisation de faisceau et applications
Collaboration
FZD
Vavilov U.
CPhT
M. Nakatsutsumi, S. Buffechoux, A. Mancic, P. Antici, P. Audebert
M. Tampo, Y. Fukuda, H. Daido
O. Willi, T. Toncian, M. Amin
M. Borghesi, L. Romagnani, G. Sarri
R. Kodama, A. Kon
H. Pépin, S. Fourmaux
T. Cowan, U. Schramm, K. Zeil, S. Kraft, T. Burris
A.Andreev
V. Tikhonchuk, J. Psikal, E. d’Humières
P. Mora
L. Gremillet, E. Lefebvre
Y. Sentoku, S. Gaillard
S. Atzeni, A.Schiavi
PMRC/KPSI
- - - - - - - - - - - - - - --
+ -+ -+ -+ -
Surface contaminant (H2O)
H+ ion
Bulk Target (Al)
e-
Laser:400 fs
5e1019 W cm-2
Proton beam characteristics:
• high number (~1013)• high energy (>10 MeV)• produced in a short time (~ few ps)• collimated (<20° divergence half angle)
Source d’ions par laser CPA
E (MeV)0 10
109
1010
1011
1012
1013
ddEdN
)srMeV1(
5 15 20
1014
E (MeV)0 10
109
1010
1011
1012
1013
ddEdN
)srMeV1(
5 15 20
1014
Energy increase: beyond present-day record of 60 MeV?
Obvious route: « brute force » (laser energy increase)
10-10
10-8
10-6
10-4
10-2
100Perf. Gaussian
Typical Real Pulse
Lo
g (
I)
Time
• 2: Use of low-density plasmas
• 3: Geometrical e- confinement
• 4: Tighest laser focusing
More clever strategies?
• 1: Decrease the target thickness (less e- spread + volumetric target heating)
P. Antici, J. Fuchs, et al., Phys. Plasmas 14, 030701 (2007).D. Neely et al., Appl. Phys. Lett. 89, 021502 (2006)T. Ceccotti et al., PRL 99, 185002 (2007)
L. Willingale et al., Phys. Rev. Lett. 96 245002 (2006)A. Yogo et al., PRE 77, 016401 (2008)
0.1
1
10
100
1016 1017 1018 1019 1020 1021
300fs – 1 ps40-60 fs100-150 fs
I2 (W.cm
-2.µm
2)
LOA
JanuspLULI
Nova PW
RAL PW
RAL VulcanRAL Vulcan
OsakaCUOS
MPQ
Tokyo ASTRATokyo
RAL Vulcan
TokyoYokohama
1022 10231024
1000
10000
simulations
experiments
Prospects for energy increase by laser intensity increase
J. Fuchs et al., Nature Physics 2, 48 (2006)
Fro
nt-
end
1st
apm
li
2nd
am
pli
3rd
am
pli
ELI laser facility
Route 3: geometrical confinement of hot electrons use of targets smaller than the « normal » sheath size
0
1
2
3
4
0 40 80 120
Nh 9 µm
R (µm)
n e (
cc)
Denser, more uniform sheath ?
S. Buffechoux, submitted (2009)
Au 2 μm thick target
4
6
8
10
12
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16
1000 104
105
106
107
max_E (feb08)max_E (feb09)
Surface (microns²)
Max. proton energy increases when reducing the target surface
Size ofstandardtargets
Comparable increase of conversion efficiency
(a) (b)
40
40
00
z (µ
m)
y (µm)-1.456
0.068
1.593
40
40
00
z (µ
m)
y (µm)-1.657
-0.144
1.369
Spreading of electrons over a large area
2D PIC simulations, A. Andreev, J. Psikal, V. Tikhonchuk
Electron energy spectra of hot electrons behind the interaction region
Effective confinement = hot electrons are reflected quickly from edges
foil of transverse width 80 foil of transverse width 20
2D PIC simulations, J. Psikal, V. Tikhonchuk, A. Andreev
Applications tirant partie des paramètres uniques de ces sources
Sondage de champs E & B :•Particules chargées•Faible taille de source résolution spatiale ~µm•Faible durée à la source résolution temporelle ~ps
Production de « matière dense et chaude »
classical plasma
denseplasma
= 1
= 10
Density ( g/cm3)
103
104
101
102
102 104100
10-4 10-2 1
= 100
highdensity matter
Al
white dwarf
ii ~ 1 5,
ii ~ 1 30,
ii ~ 1 200,
(Ze)2
a kB T =
CP
A
ns laser
CP
Ans laser
B
RAL VulcanB
2 mm 1 mm
TLaser = 0 ps TLaser = 0 ps
Force de Lorentz magnétique déflexion dépend de la direction de sondage
50 J, 1 ns at 1 µmfocal spot of 50 µmI=3-6 x1014 W/cm2
6 µm thick Al
100
200
300
400
0 100 200 300 400
100
200
300
400
0 100 200 300 400
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400
0 100 200 300 400
50
-10
-40
-30
-20
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400
0 100 200 300 400
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0 100 200 300 400Tra
nsv
. Dir
ecti
on [
μm
]
Laser Direction [μm]
Tra
nsv
. Dir
ecti
on [
μm
]
TLaser = -250 ps
8
7
6
Laser Direction [μm]
CHIC 2D hydrodynamic code (G. Schurtz, CELIA-Bordeaux): I=5x1014 W/cm2, 50 µm spot radius, =13
B in T log10(E) with E in V/m
E fieldTex ne magnetic field
Low-density plasma
High-density plasma
2D Hydrodynamic simulations exhibit 2 zones of B field with reversed amplitude
Recent application: ultrafast generation & probing of transient WDM state of matter
SolidIonization +
Electron heating
Ene
rgy
tran
sfer
to
ions
ExpansionWDM
~ 10 ps
Probe
pu
mp
Probing the local atomic structure of the matter and the
its temperature
This allows to probe local atomic structure changes using ultrafast X-ray Absorption Near-Edge Spectroscopy
1,54 1,55 1,56 1,57 1,58 1,59 1,6 1,61
Te = 0.025 eVTe = 0.077 eVTe = 0.095 eVTe = 0.13 eVTe = 0.17 eVTe = 0.43 eVTe = 0.86 eVTe = 2.6 eV
0
0,5
1
1,5
2
2,5
Photon Energy (keV)
0
0,5
1
1,5
2
2,5
1,54 1,55 1,56 1,57 1,58 1,59 1,6 1,61
Te = 0.025 eVTe = 0.1 eVTe = 0.5 eVTe = 1 eV
Photon Energy (keV)
QMDHNC-NPA
0
0,5
1
1,5
2
1,54 1,55 1,56 1,57 1,58 1,59 1,6 1,61
"Cold" shot
Te = 0.27 ± 0.15 eV
Te = 1.4 ± 0.23 eV
Te = 2.74 ± 0.25 eV
X-ra
y Ab
sorp
tion
(nor
mal
ized
to
the
"pla
teau
" w
ithou
t XA
NES
str
uctu
res)
Photon energy (keV)
Experiment
200 m
10 m
400 fs, 30 J E
Summary
Several routes for beam optimization of laser-accelerated protons:
Use of small targets high-energy ions, high-efficiency and collimation BUT requires high contrast
Use of tight focushigh-energy ions, high-efficiency AND provides high contrast
Present developed applications : generation & probing of WDM (astrophysics, ICF) and radiography of fields