Ignition by excimer laser photolysis of ozone

Lucas, Donald; Dunn‐Rankin, Derek; Hom, Kenneth; Brown, Nancy J.

doi:10.1016/0010-2180(87)90029-0

Cited by 49 publications

(14 citation statements)

References 14 publications

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“…Laser ignition has been proposed as a potential ignition source that can offer some advantages over conventional systems such as the ability to position the ignition source optimally for ignition, rather than for mounting or durability reasons (Ronney, 1994 andEl-Rabii et al, 2004). A variety of laser ignition strategies are available and these include the use of: a high flux density from a focused pulsed laser to breakdown the fuel-air premixture (Spiglanin, 1995); a wavelength tuned laser to excite a specific species within a mixture (Lucas, 1987;Forch and Miziolek, 1991) or a laser beam that is focused onto a target thereby reducing the energy flux density required (Bach et al, 1969). To date, the first option appears to be the most practical, employing relatively simple and comparatively cheap laser systems and permitting the movement of the ignition position by steering the beam.…”

Section: Introductionmentioning

confidence: 99%

Laser Ignition of Iso-Octane Air Aerosols

Lawes

Lee

Mokhtar

et al. 2007

Combustion Science and Technology

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Iso-octane aerosols in air have been ignited with a focused Nd:YAG laser at pressures and temperatures of 100 kPa and 270 K and imaged using schlieren photography. The aerosol was generated using the Wilson cloud chamber technique. The droplet diameter, gas phase equivalence ratio and droplet number density were determined. The input laser energy and overall equivalence ratio were varied. For 270 mJ pulse energies initial breakdown occurred at a number of sites along the laser beam axis. From measurements of the shock wave velocity it was found that energy was not deposited into the sites evenly. At pulse energies of 32 mJ a single ignition site was observed. Overall fuel lean flames were observed to locally extinguish, however both stoichiometric and fuel rich flames were ignited. The minimum ignition energy was found to depend on the likelihood of a droplet existing at the focus of the laser beam.3

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Section: Introductionmentioning

confidence: 99%

Laser Ignition of Iso-Octane Air Aerosols

Lawes

Lee

Mokhtar

et al. 2007

Combustion Science and Technology

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“…It is worth noting that the use of laser radiation for affecting combustion has been widely discussed during the past decades [5][6][7][8][9]. Until now, only three methods of laser-assisted combustion initiation, such as laser-induced thermal ignition, laser-induced photochemical ignition, and laser-induced spark ignition, have been realized in experiments.…”

Section: Introductionmentioning

confidence: 99%

Initiation of combustion by laser-induced excitation of molecular vibrations of reactants

2006

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The features of combustion initiation in H 2 /air and CH 4 (C 2 H 2 )/air mixtures under laser-induced excitation of the asymmetric mode of ozone molecules added in a small amount to the mixture are analyzed. It was shown that such an approach to supply radiation energy to the combustible mixtures reduces the induction time and decreases the ignition temperature at a small energy of laser radiation delivered to the mixture. These effects are explained mostly by two factors -the intensification of chain reactions due to acceleration of O-atom formation during dissociation of vibrationally excited O 3 molecules and the heating of the mixture due to a faster decomposition of O 3 molecules. The considered method of ignition/combustion control is much more effective (by a factor of 10-100) than the method based on heating the gas by resonance laser radiation in the case where the characteristic time of highly reactive radical and atom formation does not exceed significantly the relaxation time of the asymmetric mode of the O 3 molecule.

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“…The duration and the energy of a pulse are 200 ms and up to 800 mJ, respectively. The volume of the combustion cell is 160 Â 160 Â 100 mm 3 . Four blocks of silicon window with an area of 85 Â 48 mm 2 are mounted on the sides of the cell for the incidence of the laser pulse, the recording of the experimental spectrum, and the capturing of the images.…”

Section: Methodsmentioning

confidence: 99%

“…As a laser pulse with a wavelength of !250 nm is employed to induce the plasma in the gas, a gaseous molecule or atom has to simultaneously absorb a number of photons for these free electrons since the photon energy is usually lower than the ionization potential [1][2][3][4][5]. Therefore, multi-photon ionization process is the only origin of initial free electrons in clean gas without external preionization [1].…”

Section: Introductionmentioning

confidence: 99%

Characteristics of plasma induced by interaction of a free-oscillated laser pulse with a coal target in air and combustible gas

Yang

Peng

2010

International Journal of Hydrogen Energy

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Free-oscillated Nd:YAG laser Laser ignition Radical spectrumHydrogen-oxygen mixture a b s t r a c t Plasma in the air is successfully induced by a free-oscillated Nd:YAG laser pulse with a peak power of 10 2-3 W. The initial free electrons for the cascade breakdown process are from the ablated particles from the surface of a heated coal target, likewise induced by the focused laser beam. The laser field compensates the energy loss of the plasma when the corresponding temperature and the images are investigated by fitting the experimental spectra of B 2 P þ / X 2 P þ band of CN radicals in the plasma with the simulated spectra and a 4-frame CCD camera. The electron density is estimated using a simplified Kramer formula. As this interaction occurs in a gas mixture of hydrogen and oxygen, the formation and development of the plasma are weakened or restrained due to the chaining branch reaction in which the OH radicals are accumulated and the laser energy is consumed.Moreover, this laser ignition will initiate the combustion or explosion process of combustible gas and the minimum ignition energy is measured at different initial pressures. The differences in the experimental results compared to those induced by a nanosecond Q-switched laser pulse with a peak power of 10 6-8 W are also discussed.

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Ignition by excimer laser photolysis of ozone

Cited by 49 publications

References 14 publications

Laser Ignition of Iso-Octane Air Aerosols

Laser Ignition of Iso-Octane Air Aerosols

Initiation of combustion by laser-induced excitation of molecular vibrations of reactants

Characteristics of plasma induced by interaction of a free-oscillated laser pulse with a coal target in air and combustible gas

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