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

Journal Article · Thu Nov 01 00:00:00 EDT 2012 · Journal of Applied Physics

DOI:https://doi.org/10.1063/1.4764060· OSTI ID:22089558

Verhoff, B.; Harilal, S. S.; Freeman, J. R.; Diwakar, P. K.; Hassanein, A. ^[1]

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1. Center for Materials Under Extreme Environment and School of Nuclear Engineering, Purdue University, West Lafayette, Indiana 47907 (United States)

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.

• OSTI ID: 22089558
• Journal Information: Journal of Applied Physics, Vol. 112, Issue 9; Other Information: (c) 2012 American Institute of Physics; Country of input: International Atomic Energy Agency (IAEA); ISSN 0021-8979
• Country of Publication: United States
• Language: English

Related Subjects

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