Post on 28-Dec-2019
The Third Blaise Pascal Lecture Wednesday 9th December 2009
Ecole PolytechniqueAmphi Faurre
Laser Ion Acceleration
Toshiki TajimaBlaise Pascal Chair,
Fondation Ecole Normale SupérieureInstitut de Lumière Extrême
andLMU,MPQ, Garching
Acknowledgments for Advice and Collaboration: G. Mourou, V. Malka, J. Fuchs, C. Labaune, P. Mora, F. Krausz, D. Habs, T. Esirkepov, S. Bulanov, S. Kawanishi, M. Hegelich, Y. Kishimoto, D. Jung, D. Kiefer, X. Yan, A. Henig, R. Hoerlein, S. Steinke, W. Sandner, Y. Fukuda, A. Faenov, M. Tampo, P. Bolton, Y. Ueshima, N. Rostoker, F. Mako, L. Yin, T. Pikuz, A. Pirozgkov, M. Borghesi, M. Gross
Advent of collective acceleration (1956)
Prehistoric activities (1973-75,…84)Collective acceleration suggested:
Veksler (1956)(ion energy)~ (M/m)(electron energy)
Many experimental attempts (~’70s):led to no such amplification
(ion energy)~ (several)x(electron)
Mako-Tajima analysis (1978;1984)sudden acceleration, ions untrapped,electrons return, while some run away#1 gradual acceleration necessary
#2 electron acceleration possible with trapping (with Tajima-Dawson field), more tolerant for sudden process
Professor N. Rostoker
Path once trodden
Collective accelerationof ions by electron beam
F.Mako / T. Tajima
Ions left out, while electronsshoot backward
laser electron acceleration(1979)
laser ion acceleration oflimited ion mass
(2009)
Example of solid target ca.1999
Tajima: LLNL (1999)
Toward Less Sudden Acceleration ca.1999)
Patent (Tajima) : submitted from LLNL (2002); granted (2005)
Recent breakthroughsFrom incoherent (or heating) of electrons
to Coherent drive of them
TNSA (Target Normal Sheath Acceleration)
CAIL (Coherent Acceleration of Ions by Laser)
Tajima et al., 2009
Comparison of the phase space dynamics: toward more Adiabatic Acceleration
TNSA
CAIL
(metallic boundary)
CAIL (with CP)
Rev. Accel. Sci. Tech.(Tajima, Habs, Yan, 2009)
Ion trapping width:vtr,ion ~ c a0 (m/M)
a=eE/me c
Maximal energy of protons (MeV)LLNL(redef. Ipeak )
CUOS
(rede
f. I pe
ak)
1355 (MeV)LLNL
Best s
calin
g max
a2
(T.Esirkepov et al.2006)
Optimal Thickness Scaling
Normalized thickness ~ a0
Recent Experimental Breakthroughs
Leadershipby Dieter Habs
LMU,MPQ,Max-Born Institute, LANL,RAL,PMRC
Nanometer target:DLC
Sharp contrast laserdouble plasmamirrors
More coherentelectron dynamicsin ~ a0
Recent experiments in CAIL Regime
(Henig et al, 2009;Steinke et al.)
Ultrathin film : = a0 , where = d n / nc ( = /a0 )High laser contrast: not to destroy ultrathin target
MAP + MBI
=1
Conversion efficiency of laser to ion energy
Conversion efficiency of laser energy to ion energy comparing results from thick targets and the TNSA mechanism to measurements with ultra-thin targets in the regime of CAIL (red diamonds and line).
187x10
5x1019 W/cm2
6x1019
1x1019
2x1018
7x1019
2x1020
203x10NOVA
100
10
1
0.1
0.01
Lase
r−io
n en
ergy
conv
ersi
on e
ffici
ency
[%]
10 100 103 104
Laser pulse duration [fs]
thin foil RPAthick foil TNSA
ASTRA
RAL
Two orders of magnitude higher efficiency in CAIL
Tajima, et al(2009)
Maximum energies of ions
Fig. 11. Maximum cutoff energies of ions given in MeV/u as a function of laser pulse duration. The energy gain by CAIL experiments is embedded with red dots in the predicted curves of TNSA. Note that in shorter pulses, energies by CAIL aremore than an order of magnitude higher than TNSA.
1022
1018
1021 W/cm2
7x1018
197x102x102019
10 100 103 104
Laser pulse duration [fs]
0.1
1
100
1000
10
10
10
20
19
protons, nm foil
carbon, clustercarbon, nm foil
Max
imum
cut
off i
on e
nerg
y [M
eV/u
]
ASTRAprotons, TNSA
RAL
NOVA 203x102x1020
5x10
Tajima et al.(2009)
Laser -Thin Foil Interaction
X. Yan et al., 2009
Toward monoenergy spectrum• Circularly polarized laser irradiation
more adiabatic acceleration more monoenergy
Carbon spectrum for three consecutive shots using circular polarized light at 5 *10^19 W/cm2 and a DLC foil target thickness of 5.9 nm
Coherent electron dynamics
4 6 8-180
-120
-60
0
60
120
180
Ele
ctro
n di
verg
ence
ang
le
x( )
Electron dynamics from thin foil: 3 clear patterns
Laser
Expanded target
laser transmitted
Characterization of coherent dynamics of electrons
0.1 1 100
1
2
3(c)
Coherence paramter:
Dimensionless thickness parameter normalized to a0
LP CP
Energy Gain in Laser Ion acceleration: CAIL (Coherent Acceleration of Ions by Laser) regime
• When electron dynamics by laser drive is sufficiently coherent, with coherence parameter of electrons, the ion energy in terms of electron energy is :
Electron energy = ponderomotive energy
Ion energy
(the more coherent the electron motion, the higher the ion energy)
maximizes at = 1
CAIL Theory PredictionCAIL (Coherent Acceleration of Ions by Laser) theory has definitiveprediction of max energies
Tajima et al. (2009)
For the case of LANLexperiment prediction (relative long pulse with nm targets)
Ponderomotive Bucket Formation
Gradual dynamicsof the ponderomotivebucket
PonderomotiveForce Electrostatic Trapping of ions
Yan et al. (2008)
Synchrotron oscillations in the bucket
(a,b,c)Evolution of phase space distribution for protons, the 1st, 2nd and 3rd oscillation period are 8, 8 and 10 T respectively. (d)Energy spectrum of protons.
Laser drives accelerating bucket, more adiabatic trapping structure
Monoenergy spectrum
Yan et al.(2008)
Circularly polarized laser driven
CP laser drives ions out of ultrathin (nm) foil adiabaticallyMonoenergy peak emerges
laser
Ion population
Ion mom
emntum
Ponderomotive force drives electrons,Electrostatic force nearly cancelsSlowly accelerating bucket formed
Bucket trapping ions
(X. Yan et al: 2009)
Vi,tr
Vi,tr = c (a0 m/M)
Phase space of carbon ions in 2D
Longitudinal phase space of carbon ions in 2D simulations. (a) Stable bucket structure of synchrotron oscillation; (b) Collapse of the accelerating bucket when the plasma becomes hot (due to the bending of the target)
Trapped in the bucket Bucket breaks down by runaway e-
t = 28 TL t = 40 TL
Toward more adiabatic acceleration(4)
0 10 20 30 40 50 60 70 80
0
200
400
600
800
1000
CP LP
Max
. Ene
rgy(
MeV
)
Normalized laser amplitude a0
The more adiabatic, the longer accelerated, the higher energy
Energy by CP tends to increase as ~ a02
100TW
1PW
Monoenergetic electron bunch
(Kiefer et al, 2009)
MAP + MBI
Ultrathin (2nm) foil irradiation drives monoenergetic electronsCP
Adiabatic (Gradual) Acceleration from #1 lesson of Mako-Tajima problem
Inefficient if suddenly
accelerated
Efficient when
gradually accelerated
Accelerating structure
protonsAccelerating structure
Lesson #1: gradual acceleration Relevant for ions
(cf.human trapping width:vtr,human ~ 1m/s << cs )
c
c
Adiabatic acceleration (2) Thick metal target
laser protons electrons
Graded, thin (nm), or clustered target and/or circular polarization
Most experimental configurations of
proton acceleration(2000-2009)
Innovation (“Adiabatic Acceleration”)
(2009-)= Method to make the electrons
within ion trapping width
However, in ELI automaticvtr, ion ~ c a0 (m/M) ~ c
(ultrarelativistic a0 ~ M/m )
An optimization toward adiabatic acceleration
0pl
cr cr
ndl nla
n n
,||0
la sla
,lasl R
2 2 ( )( ) pe
g
xv x c
1/ 2
0( ) exp e
i
m x Rn x nm
(Tajima, Bulanov, Esirkepov, 2007)
Laser Pulse Conditions
Adiabatic laser-plasma interaction
Relativity Helps Acceleration (for Ions, too!)
In relativistic regime,photon electronsand even protonscouple stronger.
(Tajima, 1999 @LLNL; Esirkepov et al.,PRL,2004)
Strong fields:rectifies laserto longitudinal fields
code
Monoenergy beam from double layer target
Esirkepov et al.(2002)
Laser Piston (radiation pressure) Acceleration
Esirkepov et al. (2004)
Radiation dominant regime
Nanostructured target
(Habs, 2009)
Main laser
CO2 clusterBackground gas (He)
Three-stepconical nozzle
Target gas:60-bar He(90%) + CO2 (10%)
Probe Laser
CR39 stack
2 mm
Nozzle output
Main laser
Shadowgraph
Cluster Target Irradiation
Order of magnitude energy gainWith a modest (140mJ) laser, to go beyond 15MeV/nucleon by cluster
target
Fukuda et al. (PRL 2009)
FSSR
Laser beam
Off axis
parabola
Cluster jet x�’
X Y
Z
20
to shadowgraphimaging optics
Probe beam
Z = 0.7 mm
Z = 1.5 mm
Z = 3.5 mm
Z = 5.5 mm
Z = 8.5 mm
2 mm
Orifice output
x = 6.5 mm
4.0 mm
3.8 mm
2.1 mm
1.8 mm
1.3 mm
X =
18.627 Å 18.627 Å
Ly
O VIIIHe
OVII
(a)
(c)
(b)
Fig.15
Laser beamLaserbe
am
Faenov et al., 2009
-0.006 -0.003 0.000 0.003 0.006
1E-3
0.01
0.1
f(v)*
107
v/c
1010100 100Ei (keV)
200 200
Ly
Side
Front
-0.006 -0.003 0.000 0.003 0.006
1E-3
0.01
0.1
f(v)*
107
v/c
1010100 100Ei (keV)
200 200
He
Side
Front
(b)
z�’
FSSR(Side)
FSSR( Front)
Laser beamOff axis
parabola
Clusterjet
CR 39 (Side)
1 µm C3
H6
foil
x�’
X Y
Z
2020
1 µm C3
H6
foil
CR 39 (Front)
(a)
Fig.11
20
Faenov et al.,2009
Cluster ions strongly energized
Laser-carbon cluster interaction
a0 =4
ion
electron
laser
Ion energy~ pulse length(laser energy)
Kishimoto (2009)
Pulse Strength
Maximum energy vs. laser intensity
20max 112 aQ
Consistent to the Theory by Yan et al. (2009),though it is based on thin film case
Cluster target scaling
Ion Energy spectrum r=125 m
150.98MeV 178.84MeV114.9MeV 171.71MeV
Ion Energy vs. Cluster Radius
Radius [nm]
Cluster target scaling: ion energy ~1/(cluster radius)
Kishimoto,Tajima(2009)
Toward Compact Laser-Driven Ion Therapy
Laser particle therapy (image-guided diagnosis irradiation dose verification)targeting at smaller pre-metastasis tumors with more accuracy
PET or ray image of autoradioactivation
Proton accelerator+gantry
laser
prostate cancerrectum
X-ray IMRT Proton IMRT
Merci Beaucoup et a la Prochaine Fois!
January 20, 2010: “Relativistic Engineering”February: “High Field Science”March: “Photonuclear Physics”April: “Medical Applications”
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