1. FSC 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. FSC 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 intensity High energy content

4. FSC 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 S Plasma Wakefield Accelerators Is a Major Driver behind the Field of Ultra Short-Pulse Laser and Beam – Plasma Interactions Plasma ion channel exerts restoring force => space charge oscillations Immobile ions & relativistic ‘cold’ electrons Synchrotron radiation Blowout Regime Rosenzweig et al. 1990, Puhkov and Meyer-ter-vehn 2002, Lu et al, 2006 and 2007 Driven by an electron beam Driven by a laser pulse Large wake for a laser amplitude a o =eE o /m  o c ~ 1 or a beam density n b ~ n o Laser and beam requirements on I, , P require 100TW to PW laser and beam (such as at SLAC) facilities

7. One-on-One Simulations Agree with Experiment Nature 445 741 15-Feb-2007 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

8. Validation: OSIRIS simulation of LBNL Nature experiment Excellent agreement? Total # of electrons: Simulation: 1.7 10 9 Experiment: 2x10 9 Central energy: Simulation: 90 MeV Experiment: 86 Energy spread: Simulation: 10 MeV Experiment: 1.8 MeV

9. +10 GeV in uniform plasma 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 Energy chirp adjust initial beam position Energy chirp adjust initial beam position @ 21.7 cm @ 5.4 cm 5.4 cm 21.7 cm Laser spot evolution Spectral evolution Phase-space evolution Diffraction: weaker self-channeling Main results

10. Setup for  -ray generation and photonuclear reaction production - is direct laser interaction with nucleus possible? 238 U( ,fission) 1 10 100 0 Cross section (mbarn) 200 150 100 50 Incident  -ray energy (MeV) Samples 12 C, 63 Cu, 238 U He gas 2.10 19 e/cm 3 40 TW, 30 fs, I=10 19 W/cm 2 Supersonic nozzle 100-150 MeV e - Laser Ta-converter  Cross-section 3 mm 238 U 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. FSC 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. FSC Future Ultra-High Intensity Lasers Can Test Fundamental Physics Laws Today’s laser has I~10 22 W/cm 2 (Michigan) –Electron radiation damping important Ambitious ILE/ELI projects aim at 10 25 W/cm 2 in 2014 –20 PW, 10 24 W/cm 2 beam in 2011 At 10 23 W/cm 2, the Unruh effect can be tested (radiation from an accelerated vacuum) The Schwinger limit: 10 30 W/cm 2 –Spontaneous pair creation

13. FSC 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. FSC 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 channeling/hole-boring pulse ignition pulse

15. FSC 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 V t ~0.03c ~2C s (at 500 keV) Channel wider than laser width –Laser hosing/channel branching seen Stages of channeling process E laser nini

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

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

18. Intense laser-overdense plasma interactions X2 130µ X1 150µ 51µ 41µ 20µ laser Flux diagnostic planes 44  0.8  Isolated boundaries- we believe this is essential –100 n c Plasma 20  radius resistive core –particle drag Force = -k p  -2 –passes low and high energy particles ( 10MeV) Box size 150  x130  –5x10 8 cell –Grid size: 0.05 c/  0, 0.5 c/  p –4 electrons per cell, 10 9 particles –Te = 1.0 keV, m I = 3672m e Duration 2.5ps + –9  10 4 time steps –1 - 2 months real time 1  -laser, W 0 = 20  –Spot size matches core

19. High Intensity Laser Delivers Power to Core more Efficiently Laser Intensity 8x10 20 W/cm 2 2x10 20 W/cm 2 5x10 19 W/cm 2 8x10 20 W/cm 2 laser delivers: 5x the Power of 2x10 20 W/cm 2 laser 50x the Power of 5x10 19 W/cm 2 laser Scaled To Laser Intensity ~ 50x ~ 10x

20. Net Electron Energy Flux Spectrum Peaks at Low Energy* Through plane 0.8  m in front of core Intensity 8x10 20 W/cm 2 2x10 20 W/cm 2 5x10 19 W/cm 2 MeV Scaled to laser power @ 2.5 ps.25 MeV.9 MeV 2.6 MeV *compared to ponderomotive scaling

21. P 1 (m e c) P 2 (m e c) Energy is Transported in Hot Bulk Distribution at 1.5 ps TailHot Bulk F (log(n)) P 1 (m e c) laser Sample Region Peaks at -0.1 m e c 80% - 90% of NET energy flux 010 6 -6 -10200

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. 8x10 20 W/cm 2 @ 1 ps

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

24. Electron dynamics different @ higher intensities I 0 = 5x10 21 W/cm 2 I 0 = 1.25x10 19 W/cm 2 return current e - trapped e - accelerated e - e - from target front accelerated e - particle tracking L. O. Silva | August 2008

25. FSC 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. FSC 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. FSC 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 μm 3 need 4 trillion cells and a month on a peta-flop machine