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

e+e- plasmas can be created by irradiating high-Z targets with ultra-intense lasers Fast ions Laser Au foil W/cm 2 for 10 p Wilks et al., Phys. Plasmas 8, 542 (2001), Liang and Wilks, PRL (1998) e+e- T hot =[(1+I 2 / ) 1/2 -1]mc 2 T hot > mc 2 when I 2 >10 18 Wcm -2 ( eE/m   > c) LLNL PW-laser striking target Au

e+e- e (Liang & Wilks 1998)

e+e-)

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 B-H trident (Nakashima & Takabe 2002 PoP) 20 40

Pair Creation Rate Rises Rapidly then plateaus above ~10 20 Wcm W/cm W/cm 2 Liang et al 1998 Nakashima & Takabe 2002 f(E) approximates a truncated Maxwellian

W.cm p s e+e- 125  m Au LLNL PW laser experiments confirm copious e+e-production Cowan et al 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 Nakashima & Takabe 2002

(Wilks & Liang 2002 Unpublished) Nakashima & Takabe 2002

(Nakashima & Takabe 2002)

Two-Sided PW Irradiation may create a pair fireball

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) e+e- e-ion ux x Ex x

Phase plot of e+e-component

Weibel Instability in 3D using Quicksilver (Hastings & Liang 2007) e+e- colliding with e+e- at 0.9c head-on P x vs x B y vs x

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

P syn P pic Calibration of PIC calculation again analytic formula

pxpx B y *100 f(  )  Interaction of e+e- Poynting jet with cold ambient e+e- shows broad (>> c/  e, c/  pe ) transition region with 3-phase “Poynting shock” ejecta ambient ejecta spectral evolution ambient spectral evolution 

ejecta e- shocked ambient e- P rad of “shocked” ambient electron is lower than ejecta electron

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 ejecta e+ ambient e- ambient ion p x /mc ByBy x B y *100 p i *10 pipi

ejecta e+ ejecta e- ambient ion ambient e-  f(  ) -10p xe -10p xej 100p xi 100E x 100B y P rad Poynting shock in e-ion plasma is very complex with 5 phases and broad transition region(>> c/  i, c/  pe ). Swept-up electrons are accelerated by ponderomotive force. Swept-up ions are accelerated by charge separation electric fields.

ejecta e- shocked ambient e- P rad of shocked ambient electron is comparable to the e+e- case

Examples of collisionless shocks: e+e- running into B=0 e+e- cold plasma ejecta hi-B, hi-  weak-B, moderate  B=0, low  swept-up 100B y ejecta swept-up 100B y 100E x 100B y 100E x -p x swept-up -p xswrpt-up ejecta

When a single intense EM pulse irradiates an e+e- plasma, it snowplows all upstream particles without penetrating t  o =10  t  o =40  LLNL PW-laser striking target B y pxpx ByBy pxpx

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

I=10 21 Wcm -2 =1  m Initial e+e- n=15n cr, kT=2.6keV, thickness=0.5  m, pxpx x ByBy EzEz JzJz

Acceleration by colliding laser pulses appears almost identical to that generated by EM-dominated outflow Poynting JetColliding laser pulses t  o =40 

x Two colliding 85 fs long, Wcm -2, =1  m, Gaussian laser pulse trains can accelerate the e+e- energy to >1 GeV in 1ps or 300  m (Liang, POP 13, , 2006) 637  m-637  m ByBy pxpx slope=0.8  x Gev

Details of the inter-passage of the two pulse trains ByBy EzEz

ByBy 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 t  o =4800 P x /100 B y /100 n/n cr

Momentum distribution approaches ~ -1 power-law and continuous increase of maximum energy with time f(  )  t  o =4000

degree  1GeV Highest energy particles are narrowly beamed at specific angle from forward direction of Poynting vector, providing excellent energy-angle selectivity t  o =4800

E laser E e+e- Maximum energy coupling reaches ~ 42%

n=0.025n=9 If left and right pulses have unequal intensities, acceleration becomes asymmetric and sensitive to plasma density, Here I =10 21 Wcm -2 Pulses transmitted at max. compression Pulses totally reflected at max. compression

2D studies with finite laser spot size: D=8  m y x x BzBz y x E em E e+e-   (degrees) y x pxpx x

Compression & Acceleration of overdense 0.5  m thick e-ion plasma slab by 2-side irradiation of I=10 21 Wcm -2 laser pulses 10*p i pepe

Acceleration of e-ion plasma by CLPA is sensitive to the plasma density n=9 n=1 n=0.01 n= p i pepe 100E x 1000E x 10000E x 10p i

e+e-e-ion f   Electron energy spectrum is similar in e+e- and e-ion cases

y x y x pxpx x E em EeEe EiEi ee 100  i  (degrees) 2D e-ion interaction with laser spot size D=8  m ion e-

Conceptual experiment to study the CPA mechanism with Three PW lasers

 e /  pe log GRB Galactic Black Holes INTENSE LASERS Phase space of laser plasmas overlaps most of relevant high energy astrophysics regimes High-  Low-  PulsarWind Blazar R  pe /c mi/me