on the modeling of double pulse laser ablation of metals
DESCRIPTION
ON THE MODELING OF DOUBLE PULSE LASER ABLATION OF METALS. M. Povarnitsyn , K. Khishchenko, P. Levashov Joint Institute for High Temperatures, RAS , Moscow , Russia [email protected] T. Itina Laboratoire Hubert Curien, CNRS, St-Etienne, France. - PowerPoint PPT PresentationTRANSCRIPT
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ON THE MODELING OF DOUBLE PULSE LASER ABLATION OF METALS
M. Povarnitsyn, K. Khishchenko, P. LevashovJoint Institute for High Temperatures, RAS, Moscow, Russia
T. ItinaLaboratoire Hubert Curien, CNRS, St-Etienne, France
XIII International Conference on Physics of Non-Ideal PlasmasChernogolovka, Russia
September 16, 2009
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• Motivation• Set-up configuration• Double pulse experiments• Numerical model
— Basic equations
— Transport properties
— Equation of state
— Fragmentation effects• Preliminary results• Summary
Outline
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Ti:Sapphire
Double pulse set-up
=0.8 mkmFWHM = 100 fs
2 x 2 J/cm2
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Experiment: single & double pulses, Cu
A.Semerok & C. Dutouquet Thin Solid Films 453 – 454 (2004)
double pulse
single pulse
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Experiment: single & double pulses
J. Hermann & S. Noël, LP3 (2008) T. Donnelly et al. J. Appl. Phys. 106, 013304 2009
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Two-temperature multi-materialEulerian hydrodynamics
Basic equations Mixture model
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Transport properties
Handbook of optical constants of solids, E. Palik et al.
on melting
K. Eidmann et al. Phys. Rev. E 62, 1202 (2000)
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Two-temperature semi-empirical EOS
1
10
1
10
0.0 0.5 1.0 1.5 2.0 2.5 3.0 3.5
Density, g/cm3
l+g
(s)
(g)
(s+l)
(l)
Te
mp
era
ture
, kK
Al
s
lg
s+g
s+l
CP
bnunstable
sp
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1
10
1
10
0.0 0.5 1.0 1.5 2.0 2.5 3.0 3.5
Density, g/cm3
P = 0 GPa P = -2 GPa P = -5 GPa
l+g
(s)
(g)
(s+l)
(l)
Te
mp
era
ture
, kK
s
lg
s+g
s+l
CP
Mechanical spallation (cavitation)
P
P
P
Time to fracture is governed by the confluence of voids
liquid + voidsunstable
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Spallation criteria
D. Grady, J. Mech. Phys. Solids 36, 353 (1988).
Energy minimization
Strain rate in laser experiments is up to 1010 s-1
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• Multi-material hydrodynamics (several substances + phase transitions)
• Two-temperature model (Te Ti)
• Two-temperature equations of state
• Wide-range models of el-ion collisions, permittivity, heat conductivity (, , )
• Model of laser energy absorption (Helmholtz)
• Model of ionization & recombination (metals)
Basic features of the model
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Simulation: single pulse
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phase states
Simulation: x-t diagram of Cu, F=1.2 J/cm2
density
laser pulse
new surface
initial surface
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Ablation depth vs. fluence
Experiment:
M. Hashida et al. SPIE Proc. 4423, 178 (2001).
J. Hermann et al. Laser Physics 18(4), 374 (2008).
M.E. Povarnitsyn et al., Proc. SPIE 7005, 700508 (2008)
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Simulation: double pulse with delay=50ps
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Simulation: delay 50 ps, density of Cu
1st pulse
2d pulse
1st pulse
2nd pulse
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Simulation: delay 50 ps, phase states of Cu
1st pulse
2d pulse
l+g
g
(g)
s
(l)
l1st pulse
2nd pulse
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Simulation: single & double pulse 22 J/cm2
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Summary
• Model describes ablation depth for single and double pulse experiments in the range 0.1 – 10 J/cm2.
• For long delays the second pulse interacts with the nascent ablation plume (in liquid phase).
• Reheating of the nascent ablation plume results in suppression of the rarefaction wave.
• Back deposition of substance caused buy the second
pulse is the reason of even less crater depth for double pulses with long delay.