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Highlights of talk : e+e- pair laser production Collisionless shocks

Highlights of talk : e+e- pair laser production Collisionless shocks Colliding laser pulses accelerator. e+e- plasmas can be created by irradiating high-Z targets with ultra-intense lasers. LLNL PW-laser striking target. e+e-. Au. T hot =[(1+I l 2 /1.4.10 18 ) 1/2 -1]mc 2

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Highlights of talk : e+e- pair laser production Collisionless shocks

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  1. Highlights of talk : • e+e- pair laser production • Collisionless shocks • Colliding laser pulses accelerator

  2. e+e- plasmas can be created by irradiating high-Z targets with ultra-intense lasers LLNL PW-laser striking target e+e- Au Thot=[(1+Il2/1.4.1018)1/2-1]mc2 Thot > mc2 when Il2 >1018 Wcm-2 (<==> eE/mw > c) Au foil Fast ions Laser 1020 W/cm2 for 10 p Wilks et al., Phys. Plasmas 8, 542 (2001), Liang and Wilks, PRL (1998)

  3. e+e- e (Liang & Wilks 1998)

  4. e+e-)

  5. B-H trident 20 40 (Nakashima & Takabe 2002 PoP) B-H pair-production has larger cross-section than trident, but it depends on bremsstrahlung photon flux and optical depth of the high-Z target

  6. Liang et al 1998 1019W/cm2 1020W/cm2 f(E) approximates a truncated Maxwellian Nakashima & Takabe 2002 Pair Creation Rate Rises Rapidly then plateaus above ~1020Wcm-2

  7. LLNL PW laser experiments confirm copious e+e-production e+e- Cowan et al 2002 2.1020W.cm-2 0.42 p s 125mm Au

  8. Nakashima & Takabe 2002 Trident dominates at early times and thin targets, but B-H dominates at late times and thick targets due to increasing bremsstrahlung photon density

  9. Nakashima & Takabe 2002 (Wilks & Liang 2002 Unpublished)

  10. (Nakashima & Takabe 2002)

  11. Two-Sided PW Irradiation may create a pair fireball

  12. Ex ux e+e- e-ion x x After lasers are turned off, e+e- plasmas expands relativistically, leaving the e-ion plasma behind. Charge-separation E-field is localized in the e-ion plasma region. It does not act on the e+e- plasma (Liang & Wilks 2003)

  13. Phase plot of e+e-component

  14. Px vs x By vs x Weibel Instability in 3D using Quicksilver (Hastings & Liang 2007) e+e- colliding with e+e- at 0.9c head-on

  15. 3D Simulations of Radiative Relativistic Collisionless Shocks B Movie by Noguchi

  16. Calibration of PIC calculation again analytic formula Ppic Psyn

  17. Interaction of e+e- Poynting jet with cold ambient e+e- shows broad (>> c/We, c/wpe) transition region with 3-phase “Poynting shock” By*100 ejecta px ambient f(g) ambient spectral evolution ejecta spectral evolution g g

  18. Prad of “shocked” ambient electron is lower than ejecta electron ejecta e- shocked ambient e-

  19. Propagation of e+e- Poynting jet into cold e-ion plasma: acceleration stalls after “swept-up” mass > few times ejecta mass. Poynting flux decays via mode conversion and particle acceleration pi px/mc ambient ion ambient e- ejecta e+ x pi*10 By By*100

  20. Poynting shock in e-ion plasma is very complex with 5 phases and broad transition region(>> c/Wi, c/wpe). Swept-up electrons are accelerated by ponderomotive force. Swept-up ions are accelerated by charge separation electric fields. 100pxi 100By ejecta e- Prad 100Ex f(g) ejecta e+ -10pxe -10pxej ambient ion ambient e- g

  21. Prad of shocked ambient electron is comparable to the e+e- case shocked ambient e- ejecta e-

  22. Examples of collisionless shocks: e+e- running into B=0 e+e- cold plasma ejecta hi-B, hi-g weak-B, moderate g B=0, low g 100By ejecta 100By 100Ex 100By swept-up 100Ex -px swept-up -pxswrpt-up swept-up ejecta swept-up swept-up

  23. When a single intense EM pulse irradiates an e+e- plasma, it snowplows all upstream particles without penetrating LLNL PW-laser striking target px px By By two=10p two=40p

  24. How to create comoving J x B acceleration in the laboratory? B B thin slab of e+e- plasma EM pulses 2 opposite It turns out that it can be achieved with two colliding linearly polarized EM pulses irradiating a central thin e+e- plasma slab

  25. By Jz Ez px x I=1021Wcm-2 l=1mm Initial e+e- n=15ncr, kT=2.6keV, thickness=0.5mm,

  26. Acceleration by colliding laser pulses appears almost identical to that generated by EM-dominated outflow two=40p Poynting Jet Colliding laser pulses

  27. Two colliding 85 fs long, 1021Wcm-2, l=1mm, Gaussian laser pulse trains can accelerate the e+e- energy to >1 GeV in 1ps or 300mm (Liang, POP 13, 064506, 2006) px By g Gev slope=0.8 -637mm x 637mm x

  28. Details of the inter-passage of the two pulse trains Ez By

  29. Particles are trapped and accelerated by multiple ponderomotive traps, EM energy is continuously transferred to particle energy Notice decay of magnetic energy in pulse tail two=4800 By By/100 n/ncr Px/100

  30. Momentum distribution approaches ~ -1 power-law and continuous increase of maximum energy with time f(g) two=4000 -1 g

  31. Highest energy particles are narrowly beamed at specific angle from forward direction of Poynting vector, providing excellent energy-angle selectivity two=4800 g 1GeV degree

  32. Maximum energy coupling reaches ~ 42% Elaser Ee+e-

  33. If left and right pulses have unequal intensities, acceleration becomes asymmetric and sensitive to plasma density, Here I<--=8.1020Wcm-2; I-->=1021Wcm-2 n=0.025 n=9 Pulses transmitted at max. compression Pulses totally reflected at max. compression

  34. 2D studies with finite laser spot size: D=8 mm Bz y y y x x x px g Eem x E e+e- x a(degrees)

  35. Compression & Acceleration of overdense 0.5 mm thick e-ion plasma slab by 2-side irradiation of I=1021 Wcm-2 laser pulses 10*pi pe

  36. Acceleration of e-ion plasma by CLPA is sensitive to the plasma density n=9 n=1 10pi 10pi 100Ex 100Ex pe n=0.001 n=0.01 10pi 10pi 1000Ex 10000Ex

  37. Electron energy spectrum is similar in e+e- and e-ion cases e+e- e-ion f g g

  38. 2D e-ion interaction with laser spot size D=8 mm e- px y y ion x x x 100gi ge Eem Ee Ei a(degrees)

  39. Conceptual experiment to study the CPA mechanism with Three PW lasers

  40. Phase space of laser plasmas overlaps most of relevant high energy astrophysics regimes PulsarWind GRB 4 3 2 1 0 High-b Blazar log<g> INTENSE LASERS Low-b mi/me Galactic Black Holes 100 10 1 0.1 0.01 Rwpe/c We/wpe

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