Intense Laser Irradiation Laboratory CNR Campus via Moruzzi, 1 - 56124 Pisa, Italy http://ilil.ipcf.cnr.it 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, 2006 - Lijiang, China

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

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

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) http://ilil.ipcf.cnr.it from satellite Pisa, Toscany the CNR Campus in Pisa

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 Laboratory @ 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)

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

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

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)

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 ≈ 2.5 1018 cm-3 LWA linear approx

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. 1999 Acceleration attributed to “Direct Acceleration” X. Wang et al. Phys. Rev. Lett. 2000 Acceleration correlated to relativistic Filamentation V. Malka et al. Phys. Plasmas 2001 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 discharges @ 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)

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

Studies on propagation - the experimental set-up - above He breakdown threshold for ASE f/5 parabola ≈13µm spot FWHM M2 ≈ 3.3 I ≈ 6 1018 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

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

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, 036403 (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)

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, 226 (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)

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

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

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

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

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

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

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

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

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

Studies on propagation - transmitted laser spectra -

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

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

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)

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, 093103 (2006)

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)

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, s00340-006-2268-0 (2006)

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, 1937 (1994) A. Gamucci, M. Galimberti, D. Giulietti, L.A. Gizzi, L. Labate, C. Petcu, P. Tomassini, A. Giulietti, Appl. Phys. B, s00340-006-2268-0 (2006)

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

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

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

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 experiment @ SLIC -Saclay

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

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 nozzle @ 22.5 ° Helium at 25 bar pressure

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

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

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)

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

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

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

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

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)

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 20-30 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.

-rays Laser electrons h/h≈ 107 h≈ 1eV h≈ 10 MeV the photon machine… -rays Laser electrons h≈ 1eV h≈ 10 MeV = E/ EL ≥ 10-5 (h8 MeV)