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

povar@ihed.ras.ru

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