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Laser Acoustic Probing of Two‐Temperature Zone Created by Femtosecond Pulse
Author(s) -
Inogamov N. A.,
Zhakhovsky V. V.,
Ashitkov S. I.,
Khokhlov V. A.,
Shepelev V. V.,
Komarov P. S.,
Ovchinnikov A. V.,
Sitnikov D. S.,
Petrov Yu. V.,
Agranat M. B.,
Anisimov S. I.,
Fortov V. E.
Publication year - 2011
Publication title -
contributions to plasma physics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.531
H-Index - 47
eISSN - 1521-3986
pISSN - 0863-1042
DOI - 10.1002/ctpp.201010111
Subject(s) - materials science , laser , warm dense matter , femtosecond , irradiation , boundary layer , optics , electron , foil method , reflection (computer programming) , pulse (music) , electron temperature , atomic physics , physics , composite material , mechanics , quantum mechanics , detector , computer science , nuclear physics , programming language
We combine theoretical and experimental methods to study the processes induced by fast laser heating of metal foils. These processes reveal themselves through motion of frontal (irradiated) and rear‐side foil boundaries. The irradiated targets are 0.3‐2 micron thick aluminum foils deposited on much thicker (150 microns) glass plate. The instant boundary positions is measured by pump‐probe technique having ∼40‐150 fs time and ∼1 nm spatial resolutions. Ultrashort laser pulse transforms a frontal surface layer with thickness d T into two‐temperature ( T e ≫ T i ) warm dense matter state. Its quantitative characteristics including its thickness are defined by poorly known coefficients of electron‐ion energy exchange α and electron heat conductivity κ . Fast laser heating rises pressure in the d T ‐layer and therefore produce acoustic waves. Propagation and reflection from the frontal and rear boundaries of these waves causes the displacement Δ x ( t ) of boundary positions. Pressure wave profiles, and hence functions Δ x ( t ), depend on thickness d T . This is why the experimental detection of Δ x ( t ) opens a way to accurate evaluation of the coefficients α and κ (© 2011 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)