19th Biennial Conference of the APS Topical Group on Shock Compression of Condensed Matter
Volume 60, Number 8
Sunday–Friday, June 14–19, 2015;
Tampa, Florida
Session U1: Detonation and Shock-induced Chemistry VII: Low Density Explosive Reactivity
2:15 PM–3:15 PM,
Thursday, June 18, 2015
Room: Grand E
Chair: Joel Carney, Naval Surface Warfare Center, Indian Head, Millicent Firestone, Los Alamos National Laboratory
Abstract ID: BAPS.2015.SHOCK.U1.1
Abstract: U1.00001 : Time-Of-Flight Mass Spectrometry of Laser Exploding Foil Initiated PETN Samples
2:15 PM–2:45 PM
Preview Abstract
Abstract
Author:
Mario Fajardo
(AFRL/RWME)
We report the results of time-of-flight mass spectrometry (TOFMS)
measurements of the gaseous products of thin film PETN samples reacting
\textit{in-vacuo}. The PETN sample spots are produced by masked physical vapor deposition of
PETN [A.S. Tappan, \textit{et al}., AIP Conf. Proc. \textbf{1426}, 677 (2012)] onto a
first-surface aluminum mirror. A pulsed laser beam imaged through the soda
lime glass mirror substrate converts the aluminum layer into a
high-temperature high-pressure plasma which initiates chemical reactions in
the overlying PETN sample. We had previously proposed [E.C. Fossum, \textit{et al}., AIP
Conf. Proc. \textbf{1426}, 235 (2012)] to exploit differences in gaseous
product chemical identities and molecular velocities to provide a
chemically-based diagnostic for distinguishing between ``detonation-like''
and deflagration responses. Briefly: we expect in-vacuum detonations to
produce hyperthermal (v $\sim$ 10 km/s) thermodynamically-stable
products such as N$_{2}$, CO$_{2}$, and H$_{2}$O,
and for deflagrations to produce mostly reaction intermediates, such as NO
and NO$_{2}$, with much slower molecular velocities -- consistent
with the expansion-quenched thermal decomposition of PETN. We observe
primarily slow reaction intermediates (NO$_{2}$,
CH$_{2}$NO$_{3})$ at low laser pulse energies, the
appearance of NO at intermediate laser pulse energies, and the appearance of
hyperthemal CO/N$_{2}$ at mass 28 amu at the highest laser pulse
energies. However, these results are somewhat ambiguous, as the NO,
NO$_{2}$, and CH$_{2}$NO$_{3}$ intermediates
persist and all species become hyperthermal at the higher laser pulse
energies. Also, the purported CO/N$_{2}$ signal at 28 amu may be
contaminated by silicon ablated from the glass mirror substrate. We plan to
mitigate these problems in future experiments by adopting the ``Buelow''
sample configuration which employs an intermediate foil barrier to shield
the energetic material from the laser and the laser driven plasma [S.J.
Buelow, \textit{et al}., AIP Conf. Proc. \textbf{706}, 1377 (2003)]. [RW PA{\#}4930]
To cite this abstract, use the following reference: http://meetings.aps.org/link/BAPS.2015.SHOCK.U1.1