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Resultats récents sur l’accélération d’ions : optimisation de faisceau et applications

Resultats récents sur l’accélération d’ions : optimisation de faisceau et applications. J. Fuchs. Collaboration. 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

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Resultats récents sur l’accélération d’ions : optimisation de faisceau et applications

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  1. Resultats récents sur l’accélération d’ions : optimisation de faisceau et applications J. Fuchs

  2. Collaboration • 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 • Andreev • V. Tikhonchuk, J. Psikal, E. d’Humières • P. Mora • L. Gremillet, E. Lefebvre • Y. Sentoku, S. Gaillard PMRC/KPSI FZD Vavilov U. CPhT S. Atzeni, A.Schiavi

  3. H+ ion e- 14 14 10 10 13 13 10 10 dN dN 12 12 10 10 W W dE d dE d 1 1 ( ( ) ) 11 11 10 10 MeV MeV sr sr 10 10 10 10 9 9 10 10 15 15 20 20 0 5 5 10 0 10 E ( E ( MeV ) ) MeV Source d’ions par laser CPA Bulk Target (Al) - - - - - - - - - - - - - - - - Surface contaminant (H2O) 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)

  4. Perf. Gaussian Typical Real Pulse 0 10 -2 10 -4 10 Log (I) -6 10 -8 10 -10 10 Time Energy increase: beyond present-day record of 60 MeV? Obvious route: « brute force » (laser energy increase) • More clever strategies? • 1: Decrease the target thickness (less e- spread + volumetric target heating) • 2: Use of low-density plasmas • 3: Geometrical e- confinement • 4: Tighest laser focusing L. Willingale et al., Phys. Rev. Lett. 96 245002 (2006) A. Yogo et al., PRE 77, 016401 (2008) 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)

  5. 2 -2 2 l I (W.cm .µm ) Prospects for energy increase by laser intensity increase J. Fuchs et al., Nature Physics 2, 48 (2006) 10000 experiments 3rd ampli 2nd ampli 1st apmli Front-end 1000 300fs – 1 ps 40-60 fs 100-150 fs simulations 100 Nova PW RAL Vulcan RAL PW RAL Vulcan LULI RAL Vulcan Janusp CUOS Osaka 10 LOA MPQ Tokyo Tokyo 1 ASTRA Tokyo Yokohama ELI laser facility 0.1 16 17 18 19 20 21 23 22 24 10 10 10 10 10 10 10 10 10

  6. Denser, more uniform sheath ? 4 Nh 9 µm 3 ne (cc) 2 1 0 0 40 80 120 R (µm) Route 3: geometrical confinement of hot electrons  use of targets smaller than the « normal » sheath size

  7. Max. proton energy increases when reducing the target surface Au 2 μm thick target 16 14 max_E (feb08) max_E (feb09) Size of standard targets 12 10 8 6 4 4 5 6 7 1000 10 10 10 10 Surface (microns²) Comparable increase of conversion efficiency S. Buffechoux, submitted (2009)

  8. Spreading of electrons over a large area 1.369 40 1.593 40 2D PIC simulations, A. Andreev, J. Psikal, V. Tikhonchuk (a) (b) -0.144 0.068 z (µm) z (µm) 0 -1.657 0 -1.456 0 0 40 40 y (µm) y (µm)

  9. Effective confinement = hot electrons are reflected quickly from edges 2D PIC simulations, J. Psikal, V. Tikhonchuk, A. Andreev foil of transverse width 80 foil of transverse width 20 Electron energy spectra of hot electrons behind the interaction region

  10. white dwarf 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 » (Ze)2  = Al a kB T

  11. B B Force de Lorentz magnétique  déflexion dépend de la direction de sondage CPA CPA ns laser RAL Vulcan 6 µm thick Al 50 J, 1 ns at 1 µm focal spot of 50 µm I=3-6 x1014 W/cm2 ns laser TLaser = 0 ps TLaser = 0 ps 1 mm 2 mm

  12. 2D Hydrodynamic simulations exhibit 2 zones of B field with reversed amplitude High-density plasma TLaser = -250 ps Low-density plasma B in T log10(E) with E in V/m 8 5 0 Tex  ne magnetic field E field -10 7 -20 Transv. Direction [μm] Transv. Direction [μm] -30 -40 6 Laser Direction [μm] Laser Direction [μm] CHIC 2D hydrodynamic code (G. Schurtz, CELIA-Bordeaux): I=5x1014 W/cm2, 50 µm spot radius, =13

  13. Recent application: ultrafast generation & probing of transient WDM state of matter WDM ~ 10 ps Ionization + Electron heating Expansion Solid Energy transfer to ions Probe pump Probing the local atomic structure of the matter and the its temperature

  14. This allows to probe local atomic structure changes using ultrafast X-ray Absorption Near-Edge Spectroscopy 200 mm 400 fs, 30 J q E 10 mm Experiment HNC-NPA QMD

  15. 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 focus • high-energy ions, high-efficiency AND provides high contrast • Present developed applications : generation & probing of WDM (astrophysics, ICF) and radiography of fields

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