The dynamics of Al/Pt reactive multilayer ignition via pulsed-laser irradiation

Journal Article · Mon Dec 07 00:00:00 EST 2015 · Applied Physics Letters

DOI:https://doi.org/10.1063/1.4937161· OSTI ID:1338394

Murphy, Ryan D. ^[1]; Reeves, Robert V. ^[1]; Yarrington, Cole D. ^[1]; Adams, David P. ^[1]

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1. Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)

Reactive multilayers consisting of alternating layers of Al and Pt were irradiated by single laser pulses ranging from 100 μs to 100 ms in duration, resulting in the initiation of rapid, self-propagating reactions. The threshold intensities for ignition vary with the focused laser beam diameter, bilayer thickness, and pulse length and are affected by solid state reactions and conduction of heat away from the irradiated regions. We used high-speed photography to observe ignition dynamics during irradiation and elucidate the effects of heat transfer into a multilayer foil. For an increasing laser pulse length, the ignition process transitioned from a more uniform to a less uniform temperature profile within the laser-heated zone. A more uniform temperature profile is attributed to rapid heating rates and heat localization for shorter laser pulses, and a less uniform temperature profile is due to slower heating of reactants and conduction during irradiation by longer laser pulses. Lastly, finite element simulations of laser heating using measured threshold intensities indicate that micron-scale ignition of Al/Pt occurs at low temperatures, below the melting point of both reactants.

• Research Organization: Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)
• Sponsoring Organization: USDOE National Nuclear Security Administration (NNSA)
• Grant/Contract Number: AC04-94AL85000
• OSTI ID: 1338394
• Report Number(s): SAND2016-12661J; 649949
• Journal Information: Applied Physics Letters, Vol. 107, Issue 23; ISSN 0003-6951
• Publisher: American Institute of Physics (AIP)
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
Heat conduction
Laser beam effects
Multilayers
Laser heating
Cameras