Real time measurement of the electron density of a laser generated plasma using a RC circuit

Year: 2007

Authors: Bredice F., Sobral H., Villagran-Muniz M., Di Rocco H.O., Cristoforetti G., Legnaioli S., Palleschi V., Salvetti A., Tognoni E.

Autors Affiliation: Centro de Investigaciones Opticas, P.O.Box 124, (1900) La Plata, Argentina;
Laboratorio de Fotofísica, Centro de Ciencias Aplicadas y Desarrollo Tecnológico, Universidad Nacional Autónoma de México, Apartado Postal 70-186 México Distrito Federal, P. O. Box 04510, Mexico;
Instituto de Física “Arroyo Seco”, Facultad de Ciencias Exactas, U.N.C.P.B.A., Pinto 399, 7000 Tandil, Argentina;
Applied Laser Spectroscopy Laboratory IPCF-CNR, Area della Ricerca di Pisa, Via G. Moruzzi 1, 56124 Pisa, Italy

Abstract: A Nd:YAG laser pulse was focused, in air or on a Cu target, between the plates of a planar charged capacitor. The plasma generates a transient redistribution of the electrical charges on the plates that can be easily measured as a voltage drop across a resistor connected to the ground plate. At the same time, the Stark broadening of the H. spectral line (656.3 nm) obtained from the optical emission spectrum of the plasma was measured. In this work, we show that the peak of electrical signal measured on the resistor is, in the energy range of our laser (30 mJ to 220 mJ) and at time delays typical of Laser-Induced Breakdown Spectroscopy applications (500-5000 ns), univocally related to the temporal evolution of the Stark broadening of the H, line. Therefore, after a proper calibration depending on the material and the experimental geometry, the peak of the electrical signal can be used to predict the temporal evolution of the electron density of the generated plasma. (c) 2007 Elsevier B.V All rights reserved.


Volume: 62 (8)      Pages from: 836  to: 840

More Information: Comisión de Investigaciones Científicas, CIC. National Research Council of Science and Technology, NST. – This work was supported by the National Autonomous University of Mexico GAPAUNAM and the National Council of Science and Technology of Mexico CONACyT. The authors also want to thank the Comisión de Investigaciones Científicas de la Provincia de Buenos Aires, Argentina, where one of the authors (F.B.) works as researcher. This activity was performed in the framework of the SAILORMAN (Southern American-Italian LIBS-Oriented Research for Material Analysis Network).
KeyWords: Electron density measurement; Ha Stark broadening; Laser-induced breakdown spectroscopy; Plasma diagnostic techniques
DOI: 10.1016/j.sab.2007.06.011

Citations: 20
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