A wide-range model for simulation of pump-probe experiments with metals
M. Povarnitsyn, K. Khishchenko, P. LevashovJoint Institute for High Temperatures RAS, Moscow, Russia
T. ItinaLaboratoire Hubert Curien, CNRS, St-Etienne, France
EMRS-2011Laser materials processing for micro and nano applications
Nice, France 12 May, 2011
• Motivation• Model
— Governing equations
— Equation-of-state
— Transport properties• Pump-probe technique• Simulation results• Conclusions
Outline
Motivation
Reflectivity R Phase shift ψ
Two-temperature hydrodynamic model
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
bn
unstable
sp
Frequency of collisions
Eidmann et al. PRE 62 (2000)
Pump-probe for cold
Elsayed et al. PRL 58, 1212 (1987)
Groeneveld et al. PRL 64, 784 (1990)
Schoenlein et al. PRL 58, 1680 (1987)
Electron-ion coupling model
Electron-ion coupling
Thermal conductivity model
Thermal conductivity of Al, Ti = Te
Permittivity model
Permittivity of Al, Ti = Troom
E. D. Palik, Handbook of optical constants of solids, 1985.
Equations of EM field
Transfer-matrix method (optics)
Born, M.; Wolf, E., Oxford, Pergamon Press, 1964.
Energy absorption
Pump-probe technique
Widmann et al. PHYSICS OF PLASMAS 8 (2001)
pump
target
CCD
probe
delay
Reflectivity of S- and P-polarized probes
Phase shift of S- and P-polarized probes
Conclusions
• Pump-probe experiments provide an integral test of the models in the theoretically difficult regime of warm dense matter
• The target material motion is evident for heating by femtosecond pulses of intensity > 1014 W/cm2.
• Phase shift of S and P-polarized pulses is different because of separated zones of absorption
• Uncertainty in the pulse energy determination of ~ 10% gives substantial deflection of the theoretical curves
Appendix
Appendix