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arXiv · 2203.04278

Unfocused laser ignition of high-pressure He-H2-O2 combustible mixtures

R. Grosso Ferreira·B. Carvalho·J. Rodrigues·R. Rodrigues·A. Smith·L. Marraffa·M. Lino da Silva
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Abstract

We report consistent ignition of high-pressure (p > 20-30 bar) hydrogen-oxygen mixtures diluted with helium, using an unfocused Nd:YAG laser. This corresponds to laser irradiances several orders of magnitude below the minimum ignition energies reported in the literature. By placing a mirror inside a cylindrical vessel and filling it up to 100 bar with H2-He or O2-He non-combustible mixtures, we obtain the pressure-dependent absorptivity of the combustible He-H2-O2 mixture. We find no measurable absorption of the laser signal by the medium, for the overall pressure range, to the experimental apparatus sensitivity (about 1% of the laser irradiance). This leads credence to the theory that ignition stems from seed electrons created by autofocusing ionization of dust/impurities in the gas.

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R. Grosso Ferreira, B. Carvalho, J. Rodrigues, R. Rodrigues, A. Smith, L. Marraffa, M. Lino da Silva. 2022-03-08. Unfocused laser ignition of high-pressure He-H2-O2 combustible mixtures. https://arxiv.org/abs/2203.04278

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