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Simulation of optical breakdown in nitrogen by focused short laser pulses of 1064 nm wavelength

Published online by Cambridge University Press:  17 October 2008

G. Tartar ,
H. Ranner ,
F. Winter  and
E. Wintner
G. Tartar*
Affiliation:
Institute of Chemical Engineering, Vienna University of Technology, Vienna, Austria
H. Ranner
Affiliation:
Institute of Chemical Engineering, Vienna University of Technology, Vienna, Austria
F. Winter
Affiliation:
Institute of Chemical Engineering, Vienna University of Technology, Vienna, Austria
E. Wintner
Affiliation:
Photonics Institute, Vienna University of Technology, Vienna, Austria
*
Address correspondence and reprint requests to: Georg Tartar, Institute of Chemical Engineering, Vienna University of Technology, Getreidemarkt 9/166, A-1060 Vienna, Austria. E-mail: gtartar@mail.zserv.tuwien.ac.at
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Abstract

A kinetic model of electron cascade growth in the electromagnetic field of a focused intense laser pulse as used for laser spark generation in gases has been numerically implemented in Visual C code. The effects considered comprise Drude absorption, diffusive kinetic and inelastic losses as well as (three-particle) electron recombination. The objectives were to illustrate the dynamic process of gas ionization, and to clarify the pressure dependence of known breakdown thresholds within a range of about 2 × 104 to 2 × 106 Pa of initial pressure. Two-dimensional (cylindric coordinates) simulations of the optical breakdown in nitrogen were conducted on a commercial PC, using constant values for the collision cross section (2 × 10−19 m2), prevalent electronic excitation states (~4.8 eV), and a laser wavelength of 1064 nm. A certain aerosol concentration on the order of 3 ppb was assumed in order to provide initial electrons for cascade growth. Exemplary results with laser pulse energy of 26 mJ, pulse duration of 14 ns and an 18 µm focal spot size illustrate the dynamic process of ionization within a very short time period of less than 0.5 ns. The kinetic energy of the electrons is found to increase sharply up to more than 100,000 K on breakdown. A series of simulations considered the minimum pulse energy of breakdown (MPE) under variation of initial pressure. Identical laser parameters as in experiments conducted previously were used and the results are in excellent agreement with respect to curve shapes, i.e., MPE ~1/p0.4 in the first experiment and MPE ~1/p0.3 in the second one. The absolute values lie within a factor of two, which is explained by model abstraction and input data uncertainties.

Keywords

Electron cascade growthLaser optical breakdownNumerical simulation
Type
Research Article
Information
Laser and Particle Beams , Volume 26 , Issue 4 , December 2008 , pp. 567 - 573
Copyright
Copyright © Cambridge University Press 2008

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References

REFERENCES

Bäuerle, D. (2000). Laser Processing and Chemistry. Berlin: Springer-Verlag.CrossRefGoogle Scholar
Bradley, D., Sheppard, C.G.W., Suardjaja, I.M. & Woolley, R. (2004). Fundamentals of high-energy spark ignition with lasers. Comb. Flame 138, 55–77.CrossRefGoogle Scholar
Engelhardt, A.G., Phelps, A.V. & Risk, C.G. (1964). Determination of momentum transfer and inelastic collision cross sections for electrons in nitrogen using transport coefficients. Phys. Rev. 135, 1566–1574.CrossRefGoogle Scholar
Fang, X. & Ahmad, S.R (2007). Saturation effect at high laser pulse energies in laser-induced breakdown spectroscopy for elemental analysis in water. Laser Part. Beams 25, 613–620.CrossRefGoogle Scholar
Fußmann, G. (2003). Introduction to Plasma Physics. Berlin, Germany: Vorlesungsskriptum Universität Berlin.Google Scholar
Godwal, Y., Taschuk, M.T., Lui, S.L., Tsui, Y.Y. & Fedosejevs, R. (2008). Development of laser-induced breakdown spectroscopy for microanalysis applications. Laser Part. Beams 26, 95–103.Google Scholar
Graf, J., Geringer, B., Herdin, G. & Klausner, J. (2005). Potential of laser ignition in fuel and emission reducing homogeneous combustion processes. Proc. of Tenth Congress of the Working Cycle in Internal Combustion Engines. Gras, Austria.Google Scholar
Kennerly, R.E. (1980). Absolute total electron scattering cross sections for N2 between 0.5 and 50 eV. Phys. Rev. A 21, 1876–1883.CrossRefGoogle Scholar
Kopecek, H. (2004). Laser Ignition of Gas Engines. Ph.D. thesis, Vienna: Vienna University of Technology.Google Scholar
Lackner, M., Tartar, G., Winter, F., Klausner, J. & Herdin, G. (2005). Simulation of Plasma Propagation of Non-resonant Laser Ignition in Gases. In Proc. of Roadshow Technology and Innovation Conference (INNONET)Györ, Hungary.Google Scholar
Morgan, G. (1975). Laser-induced breakdown of gases. Reports Prog. in Phys. 38, 621–665.CrossRefGoogle Scholar
Müsing, A., Riedl, U. & Warnatz, J. (2006). Laser-Induced Breakdown in Air and Behind Droplets: A Detailed Monte-Carlo Simulation. Heidelberg, Germany: The Combustion Institute.Google Scholar
Phuoc, T.X. (2000). Laser spark ignition: Experimental determination of laser-induced breakdown thresholds of combustion gases. Opt. Commun. 175, 419–423.Google Scholar
Phuoc, T.X. (2006). Laser-induced spark ignition fundamentals and applications. Opt. Lasers Engin. 44, 351–397.CrossRefGoogle Scholar
Radziemski, L.J. & Cremers, D.A. (1989). Laser-Induced Plasmas and Applications. New York: Marcel Dekker Inc.Google Scholar
Schade, W., Bohling, C., Hohmann, K. & Scheel, D. (2006). Laser-induced plasma spectroscopy for mine detection and verification. Laser Part. Beams 24, 241–247.CrossRefGoogle Scholar
Stöcker, H. (2004). Taschenbuch der Physik. Frankfurt, Germany: Harri Deutsch Verlag.Google Scholar
Tartar, G., Lackner, M., Ranner, H., Winter, F., Klausner, J. & Herdin, G. (2006). Development of an Optical Spark Plug for Stationary Engines – A Theoretical Approach. Detroit, MI: SAE World Congress.CrossRefGoogle Scholar
Weyl, G.M. (1989). Update on breakdown physics. Laser-Induced Plasmas and Applications. New York: Marcel Dekker Inc.Google Scholar