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High Intensity Laser and Energetic Particle – Matter Interactions

High Intensity Laser and Energetic Particle – Matter Interactions. Chuang Ren University of Rochester Workshop on Scientific Opportunities in HEDLP August 26, 2008, Washington DC. Acknowledgement

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High Intensity Laser and Energetic Particle – Matter Interactions

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  1. High Intensity Laser and Energetic Particle – Matter Interactions Chuang Ren University of Rochester Workshop on Scientific Opportunities in HEDLP August 26, 2008, Washington DC

  2. Acknowledgement • J. Tonge & W. Mori (UCLA); L. O. Silva (IST); K. Krushelnick (Michigan); A. Friedman (LLNL/LBNL); Y. Sentoku (UNR); J. Zuego (LLE)

  3. High energy content high intensity

  4. Introduction • New laser/beam sources can explore new applications and fundamental physics problems • Realizing these opportunities requires understanding in high intensity laser- and energetic particle-matter interactions • Ultra short pulse – plasma interaction (PWFA, new radiation sources, QED, …) • kJ short pulse – relativistic plasmas interactions (FI, collisionless shocks, proton accelerations…) • Energetic particle – matter interactions (FI, HIF, ….) • Long-term healthy growth of the HEDLP field needs both curiosity-driven and application-driven research • Attract and retain new talents

  5. Research program has put ultra short-pulse laser and beam physics at the Forefront of Science Acceleration, Radiation Sources, Refraction, Medical Applications

  6. Plasma Wakefield Accelerators Is a Major Driver behind the Field of Ultra Short-Pulse Laser and Beam – Plasma Interactions Blowout Regime Rosenzweig et al. 1990, Puhkov and Meyer-ter-vehn 2002, Lu et al, 2006 and 2007 Driven by a laser pulse Driven by an electron beam • Plasma ion channel exerts restoring force => space charge oscillations • Immobile ions & relativistic ‘cold’ electrons • Synchrotron radiation Large wake for a laser amplitude ao=eEo/mwoc ~ 1 or a beam density nb~ no Laser and beam requirements on I, t, s, g, P require 100TW to PW laser and beam (such as at SLAC) facilities

  7. One-on-One Simulations Agree with Experiment E-167: Energy Doubling of the 42 GeV SLAC beam in a Plasma Wakefield Full scale three-dimensional particle-in-cell simulations using the code QuickPIC identified that the energy gain Saturated due to head erosion Nature 445 741 15-Feb-2007

  8. Validation: OSIRIS simulation of LBNL Nature experimentExcellent agreement? Total # of electrons: Simulation: 1.7 109 Experiment: 2x109 Central energy: Simulation: 90 MeV Experiment: 86 Energy spread: Simulation: 10 MeV Experiment: 1.8 MeV

  9. +10 GeV in uniform plasma Laser spot evolution Main results • Two regimes for laser propagation: • Self-guiding propagation regime until 10 cm • Depletion leads to diffraction after 10 cm • Accelerating gradient in good agreement with theory • QuickPIC: 0.8 GeV/cm • Theoretical: 0.6 GeV/cm Self-guiding: stronger self-channeling Diffraction: weaker self-channeling Spectral evolution Phase-space evolution @ 5.4 cm 21.7 cm Energy chirp adjust initial beam position @ 21.7 cm 5.4 cm

  10. He gas 2.1019 e/cm3 Samples 12C, 63Cu, 238U 40 TW, 30 fs, I=1019 W/cm2  Laser 3 mm U 238 100-150 MeV e- Supersonic nozzle Ta-converter Cross section (mbarn) 200 238U(,fission) 150 100 50 0 1 10 100 Incident -ray energy (MeV) Setup for -ray generation and photonuclear reaction production- is direct laser interaction with nucleus possible? Cross-section 70-75% of the -radiation in the relevant energy range (6-25 MeV) is contained within a half angle of ~9 degrees with respect to the incident electron direction. (Courtesy K. Krushelnick) S. Reed et. al. APL 2006

  11. We have developed a systematic understanding of many LPI phenomena • Fundamental processes such as SF & hosing are understood • Mutual interactions btw laser beams---braided light Braided Light, Ren et al., PRL’04

  12. Future Ultra-High Intensity Lasers Can Test Fundamental Physics Laws • Today’s laser has I~1022 W/cm2 (Michigan) • Electron radiation damping important • Ambitious ILE/ELI projects aim at 1025 W/cm2 in 2014 • 20 PW, 1024 W/cm2 beam in 2011 • At 1023 W/cm2, the Unruh effect can be tested (radiation from an accelerated vacuum) • The Schwinger limit: 1030 W/cm2 • Spontaneous pair creation

  13. Upcoming kJ-class short pulses open up new LPI regimes of LPI • Significant ion density modification • Density profiles dynamically determined • Significant plasma heating • Relativistic electron temperatures • Laser absorption coupled to density profile evolution • Many applications requires understanding of energetic particle – matter interactions • Interactions with self-generated fields

  14. ignition pulse channeling/hole-boring pulse Propagation of high-intensity pulses in underdense plasmas • Intense laser – underdense plasma interactions are important to • Fast ignition • Laser – solid experiments in general due to pre-pulses • Intense lasers cannot propagate as linear waves • Laser self-focusing and hosing • Transverse and longitudinal denisty modification • Propagation via ponderomotive push

  15. Stages of channeling process • Relativistic SF/Filament • Ponderomotive SF/Filament • Micro channels created from laser filaments • Central filament widening & shock launching • Laser snowplows away micron channel walls to form a single channel • Transverse expansion through high-mach-number shocks • Vt~0.03c ~2Cs (at 500 keV) • Channel wider than laser width • Laser hosing/channel branching seen Elaser ni

  16. A preformed channel significantly improves the transmission of the ignition pulse • The residual plasma is heated to relativistic temperatures • <>~12 • Reduced nonlinear interactions

  17. LPI in Relativistic Plasmas Is a New Research Area • Macro-size HEDLP plasmas (1 Gbar) • Relativistic pressure reduce electron quiver momentum • Vosc/c=anp/ϒ(e+p)[Tzeng & Mori, prl’98] • LPI needs to be studied in this new regime • SF & hosing • Coupling with IAW, not EPW

  18. laser X2 X1 Intense laser-overdense plasma interactions • Isolated boundaries- we believe this is essential • 100 nc Plasma • 20 m radius resistive core • particle drag Force = -k p -2 • passes low and high energy particles (<50KeV, >10MeV) • Box size 150  x130  • 5x108 cell • Grid size: 0.05 c/0 , 0.5 c/ p • 4 electrons per cell, 109 particles • Te = 1.0 keV, mI= 3672me • Duration 2.5ps + • 9104 time steps • 1 - 2 months real time • 1-laser, W0 = 20  • Spot size matches core 41µ 20µ 51µ 130µ 44m 0.8m 150µ Flux diagnostic planes

  19. High Intensity Laser DeliversPower to Core more Efficiently ~ 50x Scaled To Laser Intensity ~ 10x Laser Intensity 8x1020 W/cm2 2x1020 W/cm2 5x1019 W/cm2 8x1020 W/cm2 laser delivers: 5x the Power of 2x1020 W/cm2 laser 50x the Power of 5x1019 W/cm2 laser

  20. Net Electron Energy Flux Spectrum Peaks at Low Energy* Through plane 0.8 mm in front of core Intensity 8x1020 W/cm2 2x1020 W/cm2 5x1019 W/cm2 .25 MeV .9 MeV 2.6 MeV *compared to ponderomotive scaling MeV Scaled to laser power @ 2.5 ps

  21. Energy is Transported in Hot Bulk 80% - 90% of NET energy flux laser Peaks at -0.1 mec Sample Region 6 F (log(n)) P2 (mec) -10 0 20 -6 P1 (mec) -6 0 10 Hot Bulk Tail P1 (mec) Distribution at 1.5 ps

  22. Magnetic Filamentation and Formation of Shocks • Weibel instability relaxes anisotropic particle distributions as well as filamenting currents. • Magnetic fields reach over 100MG for high laser intensity runs - channeling usable 2 MeV energy electrons in x1 direction. 8x1020 W/cm2 @ 1 ps

  23. Dynamics in the front surface of the target Filamentation @ target Mass build up/compression & strong electric field t ~ 350 fs Weibel instability Return current L. O. Silva | August 2008

  24. Electron dynamics different @ higher intensities particle tracking accelerated e- e- from target front I0 = 5x1021 W/cm2 I0 = 1.25x1019 W/cm2 return current e- accelerated e- trapped e- L. O. Silva | August 2008

  25. Magnetic fields play the same role in the formation of laser-driven and relativistic shocks in GRB’s • GRB afterglow requires magnetic fields • Weibel instabilities from colliding shells can provide the B-field • PIC simulations of relativistic collisionless shocks (Spitkovsky ‘08,γ~15) show the same importance of the B-field • The key is to understand up- and down-stream particle distribution • Nonlinear evolution of current-driven instabilities

  26. Understanding energy loss of heavy ions in matter • Loss to free e- understood • Difficulty is in calculating loss to bound e- with self-consistent state (due to heating and collective effects) • These effects tend to increase energy loss rate • Fusion only involves fixed charge-state particles • Atomic physics is also important in laser-cone interactions Ack: A. Friedman

  27. Priority: LPI in plasmas of relativistic temperatures • Important to FI, lab astrophysics and basic science • Laser absorption in self-consistent density profiles • Particle transport in self-generated fields • Availability of kJ short pulse facilities • Peta-scale simulation capabilities to understand experiments • 3D PIC simulations of 200×100×100 μm3 need 4 trillion cells and a month on a peta-flop machine

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