Multispectral optical depth measurements in post-detonation high explosive fireballs

Lodes, Rylie Patrick

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https://hdl.handle.net/2142/105255 Copy

Description

Title

Multispectral optical depth measurements in post-detonation high explosive fireballs

Author(s)

Lodes, Rylie Patrick

Issue Date

2019-04-25

Director of Research (if dissertation) or Advisor (if thesis)

Glumac, Nick G.

Department of Study

Mechanical Sci & Engineering

Discipline

Mechanical Engineering

Degree Granting Institution

University of Illinois at Urbana-Champaign

Degree Name

M.S.

Degree Level

Thesis

Keyword(s)

• Optical depth
• Fireball
• High explosive
• Laser attenuation
• Laser absorption
• Laser scattering

Abstract

Temporally and spectrally resolved optical depth measurements were made in post-detonation fireballs from five different high explosives. PETN, HMX-based PBXN-5, RDX, an 80% RDX/20% aluminum mixture, and PETN-based Primasheet 1000 explosives were detonated in a 2.18L explosive test chamber. Charges were 125mg or 250mg explosive output pellets, each detonated by an 80mg low density PETN initiating charge. The charge configurations were based on a modified RP-80 exploding bridgewire (EBW) detonator, which is manufactured by Teledyne RISI. Five laser wavelengths were studied which cover the visible through long-wave infrared region of the spectrum. These 405nm, 532nm, 650nm, 1310nm and 9600nm lasers were used to probe the post-detonation fireballs for the first 5ms after initiation. The two charge masses were studied to understand how optical depth scales with charge mass for the same confinement volume. Data for the optical depth and wavelength and explosive composition are presented and discussed. The spectral dependence on optical depth scaled approximately as λ^(-1), which departed from the expected λ^(-4) dependence from light scattering alone. This result suggests that there is significant broadband absorption of light, in addition to scattering, through the explosive fireball. The results of this study have important implications in the interpretation of optical data collected during explosive events, as well as in the design of future experiments. The penetration depth of light through an optically dense fireball scales with wavelength and is dependent on the explosive used. It can be concluded from the data presented herein what portion of the fireball one is measuring in emission for a given high explosive, wavelength, and also how that portion changes with charge mass in confined or unconfined blasts.

Graduation Semester

2019-05

Type of Resource

text

Permalink

http://hdl.handle.net/2142/105255

Copyright and License Information

Copyright 2019 Rylie Patrick Lodes

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