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Simulation of Imploding Cylindrical Targets
R. Ramis. J. Ramírez GIFI Universidad
Politécnica de Madrid G. Schurtz CELIA
Universite Bordeaux 1
International Workshop on Physics of High Energy
Density in Matter January 19 February 3,
2006 Hirschegg, Austria
Work supported by the projects FTN2003-06901,
HF03-186 (Acción Integrada), and by the
EURATOM/CIEMAT association
Escuela Técnica Superior de Ingenieros
Aeronáuticos, P. Cardenal Cisneros 3, 28040
Madrid, SPAIN
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OCTALIL Cylindrical Target
Preliminary design to be shoot at the Ligne
d'Intégration Laser, upgraded with two
quadruplets. Expected to take place in Bordeaux
in 2008-2009
LIL facility
Experimental chamber
50 kJ in 5 ns,8 beams in octahedric configuration
CH shell 0.6 mm of radius 40 mm thickness
Filling DD at 30 bars
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Issues on experiment planing

• Complex laserplasma interaction (hydrodynamics,
  transport, absorption, ...) determine the
  implosion characteristics.
• Static irradiation (no motion) codes give only an
  estimate of the implossion uniformity based on
  simple scaling laws (i.e. Pa Ia )
• This aproach can be justified a the begining of
  the irradiation.
• Numerical simulation is needed for later times

-10
- 2
2
Guy Schurtz, FCI par attaque directe.
Utilisation de la LIL en configuration éclatée
OCTALIL ou LIL 62
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Numerical approach code MULTI

• Includes basic physics of laser-plasma
  interaction in 1D or 2D
• Hydrodynamics
• Heat transport (Spitzer flux limiter)
• Laser deposition (Bremstrahlung, ray tracing)
• Radiation transport
• Non-LTE multigroup transport (1D)
• Two temperatures (1D)
• Fusion DT reaction a-particle difussion (1D)
• Eulerian/Lagrangian hydrodynamics with
  unstructured grids (2D)
• Short pulse version (MULTIFS)
• Additional plug-ins for fusion reactions and
  a-transport
• 3D version not yet available.

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MULTI applications since 1988 hasbeen used to
simulate experiments
Ablative non-linear RT instability
Recent work
Plasma Phys. Control Fusion 46 (2004) B367-B380
1 ns
2 ns
3 ns
4ns
Heavy-ion-beam driven hohlraum target
0 ns
? (g/cm3)
Nucl. Fusion 44 (2004) 720-730
R(cm)
1D cylindrical implosion
Fast ignition with proton beams
This work
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A graphic environment has been developped

• MULTI is writen using a special computer language
  (r94) and C
• User interface
• Graphic programs to plot
• Curves
• Surfaces
• Isocontours
• Runs on Linux
• Current version
• multi2002.tar.gz
• 1107920 bytes

--Sod problem with relrho_high/rho_low entry
proto1() nx32rel4s(0 ...
(nx/2))/(nx/2) x(cut_last(s)(srel1))/(1re
l) vx0 nt500 np10 dt0.002
for(i0iltntii1) p1/(cut_first(x)-cut_
last(x)) xm0.5(cut_first(x)cut_last(x))
if(inp0)plot2d(encode("p(x,g)",idt),xm
,p) vnv((0p)-(p0))dt vn1vn0
xnxvndt vvn xxn plot2d()
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MULTI web servercurrently (february 2006) out of
service
http//server.faia.upm.es/multi
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This target is essentially tridimensional Only 1D
and 2D codes are available for us
X-ray or proton beam backlighting
Asymmetries
X-ray or proton beam backlighting
Transversal diagnostics
Axial diagnostics
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This target is essentially tridimensional Only 1D
and 2D codes are available for us
R
Z
Longitudinal simulations allow us to determine
the angle-averaged shape of the implosion
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This target is essentially tridimensional Only 1D
and 2D codes are available for us
Y
Transversal simulations allow us to determine the
central asymmetry of the implosion
X
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Longitudinal uniformity issues

• In the best case (uniform irradiation), only a
  section of the target implodes.
• End effects (jets?) take place.
• How long is the cylindrical part ?
• How are related Xlaser and Xcore?

Two parameters have been varied in this study a)
the beam aperture ? b) focus position Xfocus
s
jet
jet
Xcore
Longitudinal 2D simulations
Xlaser
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Longitudinal simulation
Initial
Density
Temperature
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Longitudinal simulation
0.5 ns
Density
Temperature
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Longitudinal simulation
1.0 ns
Density
Temperature
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Longitudinal simulation
1.5 ns
Density
Temperature
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Longitudinal simulation
2.0 ns
Density
Temperature
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Longitudinal simulation
2.5 ns
Density
Temperature
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Longitudinal simulation
3.0 ns
Density
Temperature
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Longitudinal simulation
3.5 ns
Density
Temperature
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Longitudinal simulation
4.0 ns
Density
Temperature
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Longitudinal simulation
4.5 ns
Density
Temperature
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Longitudinal simulation
5.0 ns
Density
Temperature
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Longitudinal simulation
5.5 ns
Density
Temperature
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Two configurations have been identified
The position of right and left beam rings can be
adjusted for
A) Maximum compression
B) Maximum uniformity
1 mm
Too close
2.5 mm
Too separated
Optimum
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Average density in deuterium is 1-5 g/cm3
4 g/cm3
2.2 g/cm3
CH ablator
Option A
Option B
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Azimuthal uniformity issues Transfersal
simulations

• In the best case (infinite cylinder), the finite
  number of beam directions can produce azimuthal
  distortions.
• The attainable density is limited by this fact.
• An optimum beam radius has to be found.
• Simulations are performed in 2D geometry and
  using 2D ray tracing of Gaussian beams

Numerical grid ½ of the target
?
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Transversal simulations
Initial
Density
Temperature
Grid
Power density
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Transversal simulations
0.5 ns
Density
Temperature
Grid
Power density
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Transversal simulations
1.0 ns
Density
Temperature
Grid
Power density
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Transversal simulations
1.5 ns
Density
Temperature
Grid
Power density
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Transversal simulations
2.0 ns
Density
Temperature
Grid
Power density
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Transversal simulations
2.5 ns
Density
Temperature
Grid
Power density
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Transversal simulations
3.0 ns
Density
Temperature
Grid
Power density
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Transversal simulations
3.5 ns
Density
Temperature
Grid
Power density
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Azimuthal symmetry
s0.03 mm
s0.06 mm
s0.12 mm
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Compressed configuration includes a DD hot spot
Radiation temperature
40
2000
Thermal wave
30
20
g/cm3
1000
10
eV
0
R
DD
Vertical asymmetries are due to the way XY
geometry is managed in code MULTI
Z
CH
Temperature
Density
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Maximum average DD density reaches 5-10 g/cm2
when ? ? cylinder radius
Optimum ?
?0.8 mm
?0.6 mm
?0.4 mm
?1.4 mm
Density (g/cm3)
Time (ns)

• The shape of the DD core can be very distorted
• Maximum lt?gt is not a good optimization criteria !

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Absorption and hydrodynamic efficiencies change
with ?

• Variations are moderate(?10 for 100 of change
  in ?
• Absorption increases when the corona is generated
• Absorption decreases when the target implodes

?0.042 cm
Wabsorbed / Wlaser
?0.060 cm
?0.140 cm
Time
? (cm)
? (cm)
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Importance of the radiation transport

• Corona structure is esentially the same with and
  without radiation
• Radiation losses reduce implossion energy
• Compressed configuration depends on radiative
  cooling of DD and CH
• Average density is larger

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Summary and conclusions

• Cylindrical target experiments proposed for
  OCTALIL have been analyzed.
• Two design points have been identified
• High compresion (1 mm at 4 g/cm3)
• Long configuration (2.5 mm at 2.2 g/cm3)
• Cross section 2D simulations show reasonable
  symmetry when beam radius cylinder radius
• Radiation can play an important role
• Simulations can be improved by including
• AEL hydrodynamics to solve jet structures
• Multigroup radition transport to quantify
  compressed core structure
• Laser ray tracing with refraction

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Future development of MULTI

• Include additional physics in 2D version
• Multigroup radiation transport
• Laser ray tracing with refraction
• Two matter temperatures Te and Ti
• Validation
• Experiments
• Benchmarks (recently with CHIC code from CELIA)
• Code structure
• AEL hydrodynamics
• Pure XY geometry
• Interface with SNOP and MPQEOS
• New algorithms ...

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Future development of MULTI

• Include additional physics
• Multigroup radiation transport
• Laser ray tracing with refraction
• Two matter temperatures Te and Ti
• Validation
• Experiments
• Benchmarks (recently with CHIC code from CELIA)
• Code structure
• AEL hydrodynamics
• Pure XY geometry
• Interface with SNOP and MPQEOS
• New algorithms ...

Critical to apply the code to other ICF problems,
in particular, to conically guided implosions
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Preliminary work on conically guided targets for
fast ignition
Time0
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Preliminary work on conically guided targets for
fast ignition
Time50
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Preliminary work on conically guided targets for
fast ignition
Time100
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Preliminary work on conically guided targets for
fast ignition
Time150
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Preliminary work on conically guided targets for
fast ignition
Time200
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Preliminary work on conically guided targets for
fast ignition
Time250
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Preliminary work on conically guided targets for
fast ignition
Time300
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Preliminary work on conically guided targets for
fast ignition
Time350
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Preliminary work on conically guided targets for
fast ignition
Time400
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Preliminary work on conically guided targets for
fast ignition
Time450
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Preliminary work on conically guided targets for
fast ignition
Time500
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Preliminary work on conically guided targets for
fast ignition
Time550
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Preliminary work on conically guided targets for
fast ignition
Time600
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Preliminary work on conically guided targets for
fast ignition
Time650
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Preliminary work on conically guided targets for
fast ignition
Time700
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Preliminary work on conically guided targets for
fast ignition
Time750
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Summary and conclusions

• Cylindrical target experiments proposed for
  OCTALIL have been analyzed.
• Two design points have been identified
• High compresion (1 mm at 4 g/cm3)
• Long configuration (2.5 mm at 2.2 g/cm3)
• Cross section 2D simulations show reasonable
  symmetry when beam radius cylinder radius
• Radiation can play an important role
• Simulations can be improved by including
• AEL hydrodynamics to solve jet structures
• Multigroup radition transport to quantify
  compressed core structure
• Laser ray tracing with refraction

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