Sony, George; Dr.V P N Nampoori(Cochin University of Science & Technology, September , 2011)
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Abstract:
The present thesis report the results obtained from the studies carried out on the
laser blow off plasma (LBO) from LiF-C (Lithium Fluoride with Carbon) thin film
target, which is of particular importance in Tokamak plasma diagnostics. Keeping
in view of its significance, plasma generated by the irradiation of thin film target by
nanosecond laser pulses from an Nd:YAG laser over the thin film target has been
characterized by fast photography using intensified CCD. In comparison to other
diagnostic techniques, imaging studies provide better understanding of plasma
geometry (size, shape, divergence etc) and structural formations inside the plume
during different stages of expansion.
Description:
International School of Photonics,Cochin University of Science and Technology
Girijavallabhan, C P; Nampoori, V P N; Harilal, S S; Riju, C Issac; Bindhu, C V(Journal of Physics D : Applied Physics, January 24, 1997)
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Abstract:
Optical emission studies of C2 molecules in plasma obtained by Nd:YAG
laser ablation of graphite in a helium atmosphere are reported for irradiances in the
range (1–9:2/ x 1010 W cm−2. The characteristics of the spectral emission intensity
from the C2 (Swan band) species have been investigated as functions of the
distance from the target, ambient pressure and laser irradiance. Estimates of
vibrational temperatures of C2 species under various irradiance conditions are
made. Results of measurements performed under different ambient helium gas
pressures are also discussed.
Nampoori, V P N; Girijavallabhan, C P; Harilal, S S; Riju, C Issac; Bindhu, C V(Journal of Physics D : Applied Physics, January 24, 1997)
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Abstract:
Optical emission studies of C2 molecules in plasma obtained by Nd:YAG
laser ablation of graphite in a helium atmosphere are reported for irradiances in the
range (1–9:2/ x 1010 W cm−2. The characteristics of the spectral emission intensity
from the C2 (Swan band) species have been investigated as functions of the
distance from the target, ambient pressure and laser irradiance. Estimates of
vibrational temperatures of C2 species under various irradiance conditions are
made. Results of measurements performed under different ambient helium gas
pressures are also discussed.
Harilal, S S; Issac, Riju C; Bindhu, C V; Nampoori, V P N; Vallabhan, C P G(Jpn. J. Appl. Phys, 1997)
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Abstract:
We report time resolved study of C2 emission from laser produced carbon plasma in presence of ambient helium
gas. The 1.06µm: radiation from a Nd:YAG laser was focused onto a graphite target where it·produced a transient
plasma. We observed double peak structure in the time profile of C2 species. The twin peaks were observed only
after a threshold laser fluence. It is proposed that the faster velocity component in the temporal profiles originates
mainly due to recombination processes. The laser fluence and ambient gas dependence of the double peak intensity
distribution is also reported.