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UNIVERSITY OF BUCHAREST
FACULTY OF PHYSICS Guest
2024-11-23 18:14 |
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Conference: Bucharest University Faculty of Physics 2002 Meeting
Section: Optics, Spectroscopy, Plasma and Lasers
Title:
Optical emission measurements of plasma generated
by laser ablation of Cr2O3 material in oxygen
Authors:
I.Volintiru1, M.Bazavan1, E.Aldea2, G. Dinescu2, R. Vilar3, O. Conde4
Affiliation:
1 Faculty of Physics, University of Bucharest, Romania
2 National Institute for Laser,Plasma and Radiation Physics , Magurele MG-36 , Bucharest , Romania
3 Department of Materials Engineering, Technical University of Lisbon, Lisbon, Portugal
4 Faculty of Sciences, University of Lisbon, Campo Grande Ed. C8, 1749-016 Lisbon, Portugal
E-mail
Keywords:
Abstract:
The characteristics of the transient plasma plumes generated during the pulsed laser irradiation of a Cr2O3 target are presented in this contribution. A KrF excimer laser (wavelength 248 nm, pulse width 40 ns) was used. The target was placed in a vacuum chamber and the experiments were performed in oxigen atmosphere (pressure 1 mbar). The plasma emission was viewed through a side quartz window, perpendicularly to the expansion axis. For light detection was used a variable gate (minimum gate time 3ns) proximity focused image intensifier attached to a CCD camera.
Space and time resolved emission spectroscopy measurements were performed. We could observe that, at early stages of plasma evolution, the obtained spectra contain mostly continuum. At intermediate stages the OII lines are observed over the decreasing continuum. Lately, the lines of CrII, OI and CrI become progressively noticeable. The ablation plasmas are well described by the LTE model. Consequently, temperature calculations based on the Boltzmann method are feasible. We applied the Boltzmann plot method for CrI lines and found that the corresponding points were well fitted by a line. The temperatures were determined from these lines’ slopes. The temperature values follow the plasma decay and decrease, at a distance of 1 mm from target’s surface, from 12000K to 8000K, when time varies from 90ns to 240ns.
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