1. Intense Laser Irradiation Laboratory
CNR Campus
via Moruzzi, Pisa, Italy
Antonio Giulietti
High field photonics in laser plasmas: propagation, acceleration and activation issues
ISUILS5
International Symposium on Ultrafast Intense Laser Science
November 29 - December 2, Lijiang, China

3. Visit of a delegation of the Chinese Academy of Science
to the CNR Campus in Pisa, June the 8th, 2006

4. Visit of a delegation of the Chinese Academy of Science
to the CNR Campus in Pisa, June the 8th, 2006

5. The ILIL group 2006 http://ilil.ipcf.cnr.it Marco GALIMBERTI (CNR)
Antonio GIULIETTI (CNR)
Leonida A. GIZZI (CNR)
Moreno VASELLI (CNR)
Walter BALDESCHI (techCNR)
Antonella ROSSI (techCNR)
Danilo GIULIETTI (Univ. Pisa)
Luca LABATE (CNR-INFN)
Paolo TOMASSINI (CNR-INFN)
Andrea GAMUCCI (PhD student)
Petra KOESTER (PhD student)
Tadzio LEVATO (PhD student)
Gianluca SARRI (underg. student)
from satellite
Pisa, Toscany
the CNR Campus in Pisa

6. LABORATORIES and INSTITUTIONS involved in NATIONAL PROJECTS
for the development of high power lasers devoted to
ICF, Particle acceleration, and X-Ray sources
Università di Milano - Bicocca
Università di Pisa
ILIL Intense Laser Irradiation Lab - CNR Pisa
Università di Roma - La Sapienza
Università di Roma - Tor Vergata
LNF Lab Nazionali di Frascati - INFN Frascati
NATIONAL PROJECTS:
High Field Photonics
Object: High field photonics & X-ray sources
National Coord. L.A. Gizzi (ILIL-CNR)
PlasmonX
Object: Laser acceler. & Thomson X-ray sources
HILL - High Intensity Laser LNF
National Coord. D. Giulietti (Univ. of Pisa & ILIL)
FUNDING INSTITUTIONS:
CNR Consiglio Nazionale delle Ricerche
INFN Istituto Nazionale di Fisica Nucleare
MUR Ministero per l’Università e la Ricerca
BLISS - Broadband Laser for ICF Strategic Studies
Object: Upgrade the ILIL nanosecond laser
National Coord. A. Giulietti (ILIL-CNR)
FiXer - Innovative multiporpose light sources
Object: Biomedicine & material studies
National Coord. L.A Gizzi (ILIL-CNR)

7. name 2005 2006 2007 2008 2009 place PULSED LASER PHYSICS BLISS ILIL
Broadband Laser for ICF Strategic Studies
YLF+phosphate
3ns 1053nm
2 beams
9 J/beam
single mode
diffract. limit
OPCPA tests
fs oscillator
stretching
synchronisation
Broadband
operation
1 ns
5 J
Further amplification Broad/narrow b.
1 ns 50 J
Experiments
ILIL
Pisa
TELPI
Terawatt Laser in Pisa
Ti:Sapphire
80fs 800nm
0.15 TW
10 Hz
June 2006:
2 TW
10 Hz Experiments
Possible upgrade
FLAME
Frascati Laser for Advanced Multidisciplin.
Designed
Funded
Committment
Setup
Tests
Installation.
Final test
20 fs Ti:Sa
200 TW
Fully operational
LNF
Frascati
SPARC
150 MeV
e-beam
Photoinjector
operational
Machine
assembling
SASE-FEL
and tests
operational.
Set up of the
secondary
Set up and tests
for joint operation
with the laser beam
for laser acceleration
PULSED LASER PHYSICS

8. HIGH FIELD PHOTONICS Laser Plasmas PULSED LASER PHYSICS
ADVANCED DIAGNOSTICS
Laser-electron
Scattering
Laser Plasmas
NUMERICAL SIMULATIONS
FEMTO
INTERF
High Energy
Photon Sources
SINGLE-PH
SPECTROS
High Energy
Particle Sources
ICF Plasma
Instabilities
SHEEBA
ANALYSER
DATA ANALYSIS
NUMERICAL
BLISS
1 ns
broadband
TELPI
80 fs
2 TW
FLAME
20 fs
200 TW
sync
sync
SPARC
e-Linac
PULSED LASER PHYSICS

9. laser driven plasma accelerators provides allows produce but
accelerating field
many orders of magnitude
higher than in conventional
accelerators
high em field
to excite longitudinal
plasma waves
for acceleration
collimated bunches
of energetic particles
breakdown of materials
limits the accelerating field
in conventional accelerators to
E ≈ 106 V/cm
(actual ≈ 2x105 V/cm)
but
EP [V/cm] ≈ n1/2 [cm-3]
n = 1020 cm-3
EP ≈ 1010 V/cm
(actual ≈ 109 V/cm)
based on collective effects
charged particles are accelerated
by the field EP of plasma waves
plasma wave pulsation wP = (4pe2n/m)1/2
wave amplitude depends on fraction dn
of plasma electrons involved
if dn ≈ n and vf ≈ c, then
EP ≈ (4pm)1/2 c n1/2 (Dawson limit)

10. Laser excitation of plasma waves
Plasma waves can be driven by laser pulses via ponderomotive forces
BWA
beating wave acceleration
Tajima & Dawson (1979)
suggested two ways
for plasma accelerators
driven by laser pulses
LWA
laser wakefield acceleration
pulse duration tL comparable
with the plasma wave period TP
with a gaussian pulse 2tL ≈ TP
30 fs --> n ≈ cm-3
LWA
linear
approx

11. Tajima & Dawson in 1979…
…since then, an impressive progress has been done, mostly in the LWA and related schemes…
C. Gahn et al. Phys. Rev. Lett Acceleration attributed to “Direct Acceleration”
X. Wang et al. Phys. Rev. Lett Acceleration correlated to relativistic Filamentation
V. Malka et al. Phys. Plasmas Acceleration attributed to self-modulated LWA
D. Giulietti et al, Phys. Plasmas 2002 Ultracollimated bunches from exploded thin foils
…the historic year 2004: the special issue of Nature on Dream Beams…
S. P. D. Mangles, C. D. Murphy, and Z. Najmudin, Nature 431, 535 (2004)
C. G. R. Gedds, Cs. Toth, and J. van Tilborg, Nature 431, 538 (2004)
J. Faure, Y. Glinec, and A. Pukhov, Nature 431, 541 (2004)
…year 2006: GeV electron bunches produced in cm-sized capillary Berkley…
W.P. Leemans et al, Nature Physics 2, 696 (October 2006)
…recently, laser pulses longer than required by pure LWA, at moderately relativistic intensity,
were proved to be also effective for electron acceleration…
The critical issue: reproducibility of the electron bunch parameters, including direction
Need for study and control of laser pulse propagation instabilities:
Ionization de-focusing and self-phase modulation…
Relativistic self-focusing and filamentation…
Hosing…
A. Giulietti et al, Search for stable propagation of intense femtosecond
laser pulses in gas, in publication in Las. Part. Beams (2006)

12. Nicolas BOURGEOIS, Jean-Raphael MARQUES Jean GALY, David HAMILTON
Studies on propagation
Pre-formed plasma channels
Thierry AUGUSTE, Tiberio CECCOTTI, Pascal DE OLIVEIRA, Philippe MARTIN, Pascal MONOT
CEA-DSM/DRECAM/SPAM,
Gif sur Yvette Cedex, France
SLIC facility
CEA-Saclay
In collaboration with:
Electron acceleration
Radioactivation
In collaboration also with:
Nicolas BOURGEOIS, Jean-Raphael MARQUES
LULI, Palaiseau
Jean GALY, David HAMILTON
ITU, Karlsruhe

13. Studies on propagation - the experimental set-up -
above
He breakdown
threshold for ASE
f/5 parabola
≈13µm spot
FWHM
M2 ≈ 3.3
I ≈
Wcm-2
ao ≈ 1.2 & 1.7
focus in the centre of
3 mm laminar He jet
pulse/ASE
power contrast
ratio ≈ 106
energy contrast
ratio ≈ 20
65 fs pulse
0.6 J
6 cm diam
below
He density
1.2 & 1.8
1019 at/cm-3
UHI10 laser
2 
90 degrees
high visibility
femtosecond
interferometry
imaging and
spectroscopy
of the
transmitted
pulse

14. Studies on propagation
- the UHI 10 laser pulse -
ASE level
The third-order correlation curve

15. Studies on propagation
- femtosecond interferometry -
The main plasma diagnostic was interferometry performed in the Mach-Zehnder
configuration with a probe pulse obtained by frequency doubling of a small portion
of the main pulse. The probe was directed perpendicularly to the main pulse.
The probe pulse duration was 130 fs.
It was possible to follow the dynamics of the ionization of the gas during
the propagation of the laser pulse in the 3 mm path in the gas jet:
L.A. Gizzi et al.
Femtosecond interferometry of propagation of a laminar ionization front in a gas
Phys. Rev. E 74, (2006)
The actual time/space resolution at the ionization front was limited by the transit
time of the probe across the ionized region:
M. Galimberti
Probe transit effect in interferometry of fast moving samples
JOSA A, in pubblication (2006)

16. Studies on propagation
- from the interferogram to the free electron density map -
fringe pattern
phase difference
electron density
pictures from P. Squillacioti et al.
“Hydrodynamics of microplasmas…”
Phys. Plasmas 11, (2004)
The phase difference map is obtained from the fringe pattern with an original
numerical technique based on Wavelet Transform:
P. Tomassini et al., Appl. Optics, 40, 6561 (2001)
The electron density map is obtained from the phase difference map with an original
algorithm based on Abel inversion extended to moderate axial asymmetric distributions:
P. Tomassini & A. Giulietti , Optics Comm. 199, 143 (2001)

17. Studies on propagation - free electron density -
He breakdown
threshold for ASE
below
He density
1.2
1019 at/cm-3

18. Studies on propagation - free electron density -
He breakdown
threshold for ASE
below
He density
1.2
1019 at/cm-3

19. Studies on propagation - free electron density -
He breakdown
threshold for ASE
below
He density
1.2
1019 at/cm-3

20. Studies on propagation - free electron density -
above
He breakdown
threshold for ASE
He density
1.8
1019 at/cm-3

21. Studies on propagation - free electron density -
above
He breakdown
threshold for ASE
He density
1.8
1019 at/cm-3

22. Studies on propagation - free electron density -
above
He breakdown
threshold for ASE
He density
1.8
1019 at/cm-3

23. Studies on propagation forward imaging of the focal spot no gas
- transmitted laser image -
forward imaging of the focal spot
no gas

24. Studies on propagation
- transmitted laser image -
total energy transmitted 30%
peak power transmitted 30%
forward imaging of the focal spot
propagation w/o ASE preplasma

25. Studies on propagation
- transmitted laser image -
total energy transmitted 5%
peak power transmitted 18%
forward imaging of the focal spot
propagation with ASE preplasma

26. Studies on propagation - transmitted laser spectra -

27. Studies on propagation - numerical simulation -
Laser performances : P = 10 TW,  = 65 fs FWHM.
Focusing conditions : f# = f/5, focus position z0 = 0, M2 = 3.3.
Peak intensity in vacuum : I0max = 3.261018 W/cm2.
Gas jet density : na = 1.81019 cm-3.
UHI10 third-order correlation curve
Atomic density profile
PPT vs ADK ionization rates of He
Keldysh parameter

28. Studies on propagation - numerical simulation -
Contrast : 10-3 : 1.

29. Studies on propagation - numerical simulation -
Laser intensity in the moving (pulse) frame
# 1
# 2
# 3
# 4
# 5
Time history of the degree of ionization
and laser intensity in the central cell
(r = z = 0)

30. Studies on propagation - numerical simulation -
A. Giulietti, P. Tomassini, M. Galimberti, D. Giulietti,
L.A. Gizzi, P. Koester, L. Labate, T. Ceccotti, P. D’Oliveira, T. Auguste, P. Monot, P. Martin
Pre-pulse effect on intense femtosecond laser pulse propagation in gas
Phys. Plasmas 13, (2006)

31. Studies on propagation
- REMARKS -
The experiment on propagation of a laser pulse
of moderate relativistic intensity in He of density
suitable for electron acceleration has shown a rather
stable propagation with weak refractive effects.
This scenario is substantially confirmed by simulation
Relativistic effects were not observed.
Out of the focal region, where the intensity is close
to the ionization thresholds, the ionization driven
effects act on the pulse.
In the focal region, ionization driven effects are
limited to the lateral wings of the pulse.
Though the precursors of the CPA pulse can
pre-ionize the focal region, they do not favour
propagation instabilities.
Above the gas breakdown threshold, the pre-plasma
produced by the ASE acts on the main pulse as a
cleaning spatial filter.
The direction of propagation of the pulse whas stable
within a fraction af millirad
There is an intermedite range of intensity at which:
Ionization is too fast to perturb the propagating pulse
with SPM, defocusing ….
Relativistic effects are too weak
Ponderomotive effects are too slow
(this point needs to be further investigated)

32. Pre-formed plasma channels
Plasma channels suitable for guiding focused laser
pulses were produced with nanosecond pulses simulating
the ASE associated with a CPA pulse.
Channel of a predictible variety of condions of interest
for electron acceleration were obtained.
The technique is based on the optical breakdown of gases
in the regime of “propagating threshold”
A. Gamucci, M. Galimberti, D. Giulietti, L.A. Gizzi,
L. Labate, C. Petcu, P. Tomassini, A. Giulietti,
Appl. Phys. B, s (2006)

33. Pre-formed plasma channels
the interferogram
the 3-D electron density distribution
the transversal density profile is
very close to a parabolic profile
whose parameters allow optimum
guiding of laser spots of few tens of µm’s
C.G. Durfee III, J. Linch,H.M. Milchberg
Mode Properties of a Plasma Waveguide
for High-Intensity Laser Pulses
Opt. Lett. 19, (1994)
A. Gamucci, M. Galimberti, D. Giulietti, L.A. Gizzi,
L. Labate, C. Petcu, P. Tomassini, A. Giulietti,
Appl. Phys. B, s (2006)

34. Electron acceleration
The experiment was conducted with a supersonic Helium gas-jet with basically the same set-up as for the propagation studies.
Optical interferometry was the main plasma diagnostics.
Electron diagnostics included:
a Lanex screen for the spatial (angular) electron distribution
- a magnetic spectrometer for the electron energy distribution
-- a radiochromic film stack (SHEEBA) for both space and energy distribution.
After a careful tuning of the experimental parameters (He pressure, nozzle size, nozzle inclination, focusing…) optimum conditions were found:
Helium 25 bar, nozzle 4 mm, angle 22.5°, focusing F/8 at the entrance boundary
gas jet
Laser
electrons

35. images from 12 sequential shots
Electron acceleration: data from Lanex screen
Helium 25 bar, nozzle 4 mm, angle 22.5°, focusing F/8 at the entrance boundary
images from 12
sequential shots
For the most collimated bunches (shots 1,4,5,7,10,12) the mesured divergence is ≈ 30 mrad
Radial jets of electrons were observed in many shots

36. Electron acceleration: data from magnetic spectrometer
Helium 25 bar, nozzle 4 mm, angle 22.5°, focusing F/8 at the entrance boundary

37. SHEEBA The Spatial High Energy Electron Beam Analyzer
Electron acceleration: layout of SHEEBA
SHEEBA
The Spatial High Energy Electron Beam Analyzer
Configuration used in the June 06 SLIC -Saclay

38. Electron acceleration: data from SHEEBA
Helium 25 bar, nozzle 4 mm, angle 22.5°, focusing F/8 at the entrance boundary
shot # 135 to 144
on June 29th, 2006

39. Electron acceleration: data from Lanex & SHEEBA
Helium 25 bar, nozzle 4 mm, angle 22.5°, focusing F/8 at the entrance boundary
two different single-shot
patterns on LANEX
ten shots cumulated
on a single layer of SHEEBA
electron jets feature
4 mm 22.5 °
Helium at 25 bar pressure

40. SHEEBA Analysis Procedure
REAL DATA
SIMULATION
Montecarlo
GEANT 4.2.0
scanned radiochromic layer
Original SHEEBA
spectrum reconstruction algorithms
simulated signal left by monoenergetic electron bunches on experimental-like radiochromic layers set
optical density
Nemax
Number of Electrons
reconstructed electron patterns
@ given energy
Electron spectrum
Electron angular distribution

41. Electron Angular Distribution vs Energy
Electron acceleration: data from SHEEBA
Helium 25 bar, nozzle 4 mm, angle 22.5°, focusing F/8 at the entrance boundary
Electron Angular Distribution vs Energy
9.7x108
7.8x108
6.8x108
3.8x108
E = 18 MeV
E = 25 MeV
E = 30 MeV
E = 45 MeV
3.1x108
2.1x108
1.9x108
[Electrons/MeV/sterad]
250 mrad
E = 60 MeV
E = 75 MeV
E = 100 MeV

42. Electron Spectrum (Ee/MeV vs E)
Electron acceleration: data from SHEEBA
Helium 25 bar, nozzle 4 mm, angle 22.5°, focusing F/8 at the entrance boundary
60 MeV electron pattern
Inset of 4.3 mm x 4.3 mm
Whole image
Inset
Electron Spectrum (Ee/MeV vs E)

43. Analysis of the 60 MeV Electron Signal – Horizontal Line-Out
Electron acceleration: data from SHEEBA
Helium 25 bar, nozzle 4 mm, angle 22.5°, focusing F/8 at the entrance boundary
Analysis of the 60 MeV Electron Signal – Horizontal Line-Out
50 mrad 1 2

44. Radioactivation gas jet -rays Laser electrons Ta Au Bremsstrahlung
297Au(n)296Au
gas jet
-rays
Laser
electrons Ta Au

45. Radioactivation: emission spectrum from the activated gold
333 and 355 keV
after 106
laser shots
The characteristic gamma lines associated with the decay of 196Au

46. 6.17 days Radioactivation: lifetime of 196Au expected value
measurement obtained from
both 333 and 355 keV lines
expected value
6.17 days

47. GEANT 4 Radioactivation
Bremsstrahlung spectrum calculated
from from the (,n) reaction yield and
experimentally determined relative
electron spectrum
Cross section vs  energy
for the nuclear reaction 297Au(n)296Au
GEANT 4
(7.32 ± 0.31) x 109 electrons per shot with energy above 8 MeV
(consistently with the estimation from radiochromic data)

48. High field photonics in laser plasmas: propagation, acceleration and activation issues
Summary
Propagation - A favourable regime for propagation in gas of densities suitable for electron acceleration has
been found at moderate relativistic intensity.
- In this regime the intense core of the pulse is basically free from either ionization de-focusing
or relativistic self-focusing.
- Plasmas preformed by both picosecond pedestal and ASE do not affect the propagation of
the intense core of the pulse.
- Plasma channels able to guide the pulse have been created via gas breakdown with ns pulses
which can also simulate the ASE prepulse.
Acceleration - At those moderate intensities conditions were found for fairly stable and controllable
production of collimated, nC electron bunches whose spectrum is peaked at MeV.
- Four independent detection techniques, namely Lanex, Mag. spectrometer, SHEEBA and
nuclear activation, provided a unique, self-consistent characterization of the electron bunches.
Activation The electron bunches were able to produce, via bremsstrahlung in a high-Z radiator and
gamma induced nuclear reactions, a considerable number of radionucledes.

49. -rays Laser electrons h/h≈ 107 h≈ 1eV h≈ 10 MeV
the photon machine…
-rays
Laser
electrons
h≈ 1eV
h≈ 10 MeV
= E/ EL ≥ (h8 MeV)