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Title: Dynamics of femto- and nanosecond laser ablation plumes investigated using optical emission spectroscopy

Abstract

We investigated the spatial and temporal evolution of temperature and electron density associated with femto- and nanosecond laser-produced plasmas (LPP) from brass under similar laser fluence conditions. For producing plasmas, brass targets were ablated in vacuum employing pulses either from a Ti:Sapphire ultrafast laser (40 fs, 800 nm) or from a Nd:YAG laser (6 ns, 1064 nm). Optical emission spectroscopy is used to infer the density and temperature of the plasmas. The electron density (n{sub e}) was estimated using Stark broadened profiles of isolated lines while the excitation temperature (T{sub exc}) was estimated using the Boltzmann plot method. At similar fluence levels, continuum and ion emission are dominant in ns LPP at early times (<50 ns) followed by atomic emission, while the fs LPP provided an atomic plume throughout its visible emission lifetime. Though both ns and fs laser-plasmas showed similar temperatures ({approx}1 eV), the fs LPP is found to be significantly denser at shorter distances from the target surface as well as at early phases of its evolution compared to ns LPP. Moreover, the spatial extension of the plume emission in the visible region along the target normal is larger for fs LPP in comparison with ns LPP.

Authors:
; ; ; ;  [1]
  1. Center for Materials Under Extreme Environment and School of Nuclear Engineering, Purdue University, West Lafayette, Indiana 47907 (United States)
Publication Date:
OSTI Identifier:
22089558
Resource Type:
Journal Article
Journal Name:
Journal of Applied Physics
Additional Journal Information:
Journal Volume: 112; Journal Issue: 9; Other Information: (c) 2012 American Institute of Physics; Country of input: International Atomic Energy Agency (IAEA); Journal ID: ISSN 0021-8979
Country of Publication:
United States
Language:
English
Subject:
70 PLASMA PHYSICS AND FUSION TECHNOLOGY; ABLATION; BRASS; DENSITY; ELECTRON DENSITY; ELECTRON TEMPERATURE; EMISSION SPECTROSCOPY; EXCITATION; ION EMISSION; ION TEMPERATURE; LASER-PRODUCED PLASMA; LIFETIME; LINE BROADENING; NEODYMIUM LASERS; PLASMA DENSITY; PLASMA DIAGNOSTICS; PLASMA PRODUCTION; PLUMES; STARK EFFECT; SURFACES

Citation Formats

Verhoff, B., Harilal, S. S., Freeman, J. R., Diwakar, P. K., and Hassanein, A. Dynamics of femto- and nanosecond laser ablation plumes investigated using optical emission spectroscopy. United States: N. p., 2012. Web. doi:10.1063/1.4764060.
Verhoff, B., Harilal, S. S., Freeman, J. R., Diwakar, P. K., & Hassanein, A. Dynamics of femto- and nanosecond laser ablation plumes investigated using optical emission spectroscopy. United States. doi:10.1063/1.4764060.
Verhoff, B., Harilal, S. S., Freeman, J. R., Diwakar, P. K., and Hassanein, A. Thu . "Dynamics of femto- and nanosecond laser ablation plumes investigated using optical emission spectroscopy". United States. doi:10.1063/1.4764060.
@article{osti_22089558,
title = {Dynamics of femto- and nanosecond laser ablation plumes investigated using optical emission spectroscopy},
author = {Verhoff, B. and Harilal, S. S. and Freeman, J. R. and Diwakar, P. K. and Hassanein, A.},
abstractNote = {We investigated the spatial and temporal evolution of temperature and electron density associated with femto- and nanosecond laser-produced plasmas (LPP) from brass under similar laser fluence conditions. For producing plasmas, brass targets were ablated in vacuum employing pulses either from a Ti:Sapphire ultrafast laser (40 fs, 800 nm) or from a Nd:YAG laser (6 ns, 1064 nm). Optical emission spectroscopy is used to infer the density and temperature of the plasmas. The electron density (n{sub e}) was estimated using Stark broadened profiles of isolated lines while the excitation temperature (T{sub exc}) was estimated using the Boltzmann plot method. At similar fluence levels, continuum and ion emission are dominant in ns LPP at early times (<50 ns) followed by atomic emission, while the fs LPP provided an atomic plume throughout its visible emission lifetime. Though both ns and fs laser-plasmas showed similar temperatures ({approx}1 eV), the fs LPP is found to be significantly denser at shorter distances from the target surface as well as at early phases of its evolution compared to ns LPP. Moreover, the spatial extension of the plume emission in the visible region along the target normal is larger for fs LPP in comparison with ns LPP.},
doi = {10.1063/1.4764060},
journal = {Journal of Applied Physics},
issn = {0021-8979},
number = 9,
volume = 112,
place = {United States},
year = {2012},
month = {11}
}