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Title: Laser-induced spark ignition fundamental and applications

Abstract

Laser ignition has become an active research topic in recent years because it has the potential to replace the conventional electric spark plugs in engines that are required to operate under much higher compression ratios, faster compression rates, and much leaner fuel-to-air ratios than gas engines today. It is anticipated that the igniter in these engines will face with pressures as high as 50MPa and temperatures as high as 4000 K. Using the conventional ignition system, the required voltage and energy must be greatly increased (voltages in excess of 40 kV) to reliably ignite the air and fuel mixture under these conditions. Increasing the voltage and energy does not always improve ignitability but it does create greater reliability problem. The objective of this paper is to review past work to identify some fundamental issues underlying the physics of the laser spark ignition process and research needs in order to bring the laser ignition concept into the realm of reality.

Authors:
Publication Date:
Research Org.:
National Energy Technology Laboratory (NETL), Pittsburgh, PA, Morgantown, WV, and Albany, OR
Sponsoring Org.:
USDOE - Office of Fossil Energy (FE)
OSTI Identifier:
938584
Report Number(s):
DOE/NETL-IR-2006-194; NETL-TPR-1162
Journal ID: ISSN 0143-8166; TRN: US200820%%169
DOE Contract Number:
None cited
Resource Type:
Journal Article
Resource Relation:
Journal Name: Optics and Lasers in Engineering; Journal Volume: 44; Journal Issue: 5
Country of Publication:
United States
Language:
English
Subject:
33 ADVANCED PROPULSION SYSTEMS; AIR; COMPRESSION; COMPRESSION RATIO; ELECTRIC SPARKS; ENGINES; IGNITION; IGNITION SYSTEMS; INTERNAL COMBUSTION ENGINES; LASERS; MIXTURES; PHYSICS; RELIABILITY; CHEMISORPTION; PENTACENE; SILICON; SORPTIVE PROPERTIES; MORPHOLOGY; ADSORPTION HEAT; Laser ignition; Gas breakdown; Spark evolution; Ignition mechanism; Ignition energy

Citation Formats

Tran, P.X. Laser-induced spark ignition fundamental and applications. United States: N. p., 2006. Web. doi:10.1016/j.optlaseng.2005.03.008.
Tran, P.X. Laser-induced spark ignition fundamental and applications. United States. doi:10.1016/j.optlaseng.2005.03.008.
Tran, P.X. Mon . "Laser-induced spark ignition fundamental and applications". United States. doi:10.1016/j.optlaseng.2005.03.008.
@article{osti_938584,
title = {Laser-induced spark ignition fundamental and applications},
author = {Tran, P.X.},
abstractNote = {Laser ignition has become an active research topic in recent years because it has the potential to replace the conventional electric spark plugs in engines that are required to operate under much higher compression ratios, faster compression rates, and much leaner fuel-to-air ratios than gas engines today. It is anticipated that the igniter in these engines will face with pressures as high as 50MPa and temperatures as high as 4000 K. Using the conventional ignition system, the required voltage and energy must be greatly increased (voltages in excess of 40 kV) to reliably ignite the air and fuel mixture under these conditions. Increasing the voltage and energy does not always improve ignitability but it does create greater reliability problem. The objective of this paper is to review past work to identify some fundamental issues underlying the physics of the laser spark ignition process and research needs in order to bring the laser ignition concept into the realm of reality.},
doi = {10.1016/j.optlaseng.2005.03.008},
journal = {Optics and Lasers in Engineering},
number = 5,
volume = 44,
place = {United States},
year = {Mon May 01 00:00:00 EDT 2006},
month = {Mon May 01 00:00:00 EDT 2006}
}
  • Laser-induced spark ignition of CH{sub 4}-air mixtures was experimentally investigated using a nanosecond pulse at 1,064 nm from a Q-switched Nd-Yag laser. Laser irradiance in the order of 10{sup 12} to 10{sup 13} W/cm{sup 2} was found to be sufficient to ignite a mixture having from 6.5 to 17% methane by volume (equivalence ratio, ER, from 0.66 to 1.95). The dependence of the breakdown threshold laser energy, E{sub thr}, on the gas pressure was in agreement with the electron cascade theory. Depending on the laser energy, E{sub o}, the spark absorption coefficient in the range from 0.1 to about 100more » cm{sup {minus}1} was calculated using the electron-ion inverse bremsstrahlung process. The minimum ignition energy was about one order of magnitude higher than the minimum ignition energy obtained by the electric spark ignition. It had its lowest value remaining at about 3 to 4 mJ for a mixture having 10 to 15% methane by volume (ER = 1.058 to 1.68) and it increased sharply toward the far-lean and the far-rich sides of the stoichiometry. The average length and radius of the spark for a stoichiometric or near-stoichiometric methane-air mixture were about 0.8 mm and 0.3 mm, respectively. For lean or rich methane-air mixtures, the average long axis of the spark size varied from about 0.8 to 2 mm, whereas for the short axis it varied from about 0.4 to 1.2 mm depending on the methane volume fraction.« less
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