Highlights of talk :

1

• Highlights of talk
• ee- pair laser production
• Collisionless shocks
• Colliding laser pulses accelerator

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ee- plasmas can be created by irradiating
high-Z targets with ultra-intense lasers
LLNL PW-laser striking target
ee-
Au
Thot(1Il2/1.4.1018)1/2-1mc2 Thot gt mc2 when
Il2 gt1018 Wcm-2 (ltgt eE/mw? gt 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)
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ee-
e
(Liang Wilks 1998)
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ee-)
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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
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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
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LLNL PW laser experiments confirm copious
ee-production
ee-
Cowan et al 2002
2.1020W.cm-2 0.42 p s
125mm Au
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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
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Nakashima Takabe 2002
(Wilks Liang 2002 Unpublished)
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(Nakashima Takabe 2002)
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Two-Sided PW Irradiation may create a pair
fireball
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Ex
ux
ee-
e-ion
x
x
After lasers are turned off, ee- 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 ee- plasma (Liang Wilks 2003)
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Phase plot of ee-component
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Px vs x
By vs x
Weibel Instability in 3D using Quicksilver
(Hastings Liang 2007) ee- colliding with
ee- at 0.9c head-on
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3D Simulations of Radiative Relativistic
Collisionless Shocks
B
Movie by Noguchi
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Calibration of PIC calculation again analytic
formula
Ppic
Psyn
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Interaction of ee- Poynting jet with cold
ambient ee- shows broad (gtgt c/We, c/wpe)
transition region with 3-phase Poynting shock
By100
ejecta
px
ambient
f(g)
ambient spectral evolution
ejecta spectral evolution
g
g
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Prad of shocked ambient electron is lower than
ejecta electron
ejecta e-
shocked ambient e-
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Propagation of ee- Poynting jet into cold
e-ion plasma acceleration stalls after
swept-up mass gt few times ejecta mass.
Poynting flux decays via mode conversion and
particle acceleration
pi
px/mc
ambient ion
ambient e-
ejecta e
x
pi10
By
By100
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Poynting shock in e-ion plasma is very complex
with 5 phases and broad transition region(gtgt
c/Wi, c/wpe). Swept-up electrons are accelerated
by ponderomotive force. Swept-up ions are
accelerated by charge separation electric
fields.
100pxi
ejecta e-
100By
Prad
100Ex
f(g)
ejecta e
-10pxe
-10pxej
ambient ion
ambient e-
g
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Prad of shocked ambient electron is comparable to
the ee- case
shocked ambient e-
ejecta e-
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Examples of collisionless shocks ee- running
into B0 ee- cold plasma ejecta hi-B,
hi-g weak-B, moderate g B0,
low g
100By
ejecta
100By
100By
100Ex
swept-up
100Ex
-px swept-up
-pxswrpt-up
swept-up
ejecta
swept-up
swept-up
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When a single intense EM pulse irradiates an
ee- plasma, it snowplows all upstream
particles without penetrating
LLNL PW-laser striking target
px
px
By
By
two10p
two40p
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How to create comoving J x B acceleration
in the laboratory?
B
B
thin slab of ee- plasma
EM pulses
2 opposite
It turns out that it can be achieved with two
colliding linearly polarized EM pulses
irradiating a central thin ee- plasma slab
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By
Jz
Ez
px
x
I1021Wcm-2 l1mm Initial ee- n15ncr,
kT2.6keV, thickness0.5mm,
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Acceleration by colliding laser pulses appears
almost identical to that generated by
EM-dominated outflow
two40p
Poynting Jet
Colliding laser pulses
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Two colliding 85 fs long, 1021Wcm-2, l1mm,
Gaussian laser pulse trains can accelerate the
ee- energy to gt1 GeV in 1ps or 300mm (Liang, POP
13, 064506, 2006)
px
By
g
Gev
slope0.8
x
637mm
-637mm
x
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Details of the inter-passage of the two pulse
trains
Ez
By
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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
two4800
By
By/100
n/ncr
Px/100
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Momentum distribution approaches -1 power-law
and continuous increase of maximum energy with
time
f(g)
two4000
-1
g
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Highest energy particles are narrowly beamed at
specific angle from forward direction of Poynting
vector, providing excellent energy-angle
selectivity
two4800
g
1GeV
degree
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Maximum energy coupling reaches 42
Elaser
Eee-
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If left and right pulses have unequal
intensities, acceleration becomes asymmetric and
sensitive to plasma density, Here
Ilt--8.1020Wcm-2 I--gt1021Wcm-2
n0.025
n9
Pulses transmitted at max. compression
Pulses totally reflected at max. compression
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2D studies with finite laser spot size D8 mm

Bz
y
y
y
x
x
x
px
g
Eem
x
E ee-
x
a(degrees)
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Compression Acceleration of overdense 0.5 mm
thick e-ion plasma slab by 2-side irradiation of
I1021 Wcm-2 laser pulses
10pi
pe
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Acceleration of e-ion plasma by CLPA is sensitive
to the plasma density
n9
n1
10pi
10pi
100Ex
100Ex
pe
n0.001
n0.01
10pi
10pi
1000Ex
10000Ex
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Electron energy spectrum is similar in ee- and
e-ion cases
ee-
e-ion
f
g
g
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2D e-ion interaction with laser spot size D8 mm
e-
px
y
y
ion
x
x
x
100gi
ge
Eem
Ee
Ei
a(degrees)
41
Conceptual experiment to study the CPA mechanism
with Three PW lasers
42
Phase space of laser plasmas overlaps most of
relevant high energy astrophysics regimes
PulsarWind
GRB
4 3 2 1 0
High-b
Blazar
logltggt
INTENSE LASERS
Low-b
mi/me
Galactic Black Holes
100 10 1 0.1
0.01
Rwpe/c
We/wpe