Detonation reactions frozen by free expansion and analyzed by mass spectrometry
The molecular design of new more powerful and less sensitive explosives requires detailed knowledge of reaction mechanisms and compositions of molecular products from explosives having a variety of molecular structures and performance parameters. We describe a new apparatus and method for analyzing detonation reactions using 30--250 mg charges. The apparatus consists of a TOF mass spectrometer interfaced to a high-vacuum firing chamber through a skimmer and a laser-schlieren optical system. The fireball normally produced by a detonation is frozen sequentially from the outside inward in a continuum of stages by free adiabatic expansion into the vacuum. Expansion of a given volume element begins when the rarefaction wave arrives from the free surface of the charge, and we find that no significant mixing occurs during the expansion. In this way the chemical history of the detonation is frozen in time and imprinted on the structure of the expanding frozen fireball. Our apparatus isolates a core sample from the expanding fireball as an undisturbed molecular beam and provides a series of mass spectra derived from successive segments of the core. The assembled data set from each pellet fired is a sequence of 95 mass spectra that characterizes the molecules resistant to change at a succession of times separated by a few (ns) in the detonation reaction. These molecules are associated with the slower (rate-determining) steps or stable products in the reaction sequence and give valuable clues to reaction mechanisms. Our mass spectrometer automatically records expansion velocities of the core segments, and an electronic framing camera concurrently records a sequences of laser-schlieren images of the detonation and expansion. The number of spectra over which a change is observed can be related, through the hydrodynamics of the detonation and expansion, to the rate of that change in the detonating sample.
- Research Organization:
- Los Alamos National Lab., NM (United States)
- Sponsoring Organization:
- USDOE; USDOE, Washington, DC (United States)
- DOE Contract Number:
- W-7405-ENG-36
- OSTI ID:
- 7198349
- Report Number(s):
- LA-UR-92-2388; CONF-9206226-1; ON: DE92018605
- Resource Relation:
- Conference: 11. annual working group institute on synthesis of high energy density materials, Monticello, NY (United States), 8-11 Jun 1992
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
37 INORGANIC
ORGANIC
PHYSICAL AND ANALYTICAL CHEMISTRY
CHEMICAL EXPLOSIVES
DESIGN
DETONATIONS
DETONATION WAVES
SCHLIEREN METHOD
MASS SPECTRA
EXPANSION
FIREBALLS
HYDRODYNAMICS
MASS SPECTROSCOPY
MOLECULAR STRUCTURE
PETN
TATB
TIME-OF-FLIGHT METHOD
ESTERS
EXPLOSIVES
FLUID MECHANICS
MECHANICS
NITRATES
NITRIC ACID ESTERS
NITROGEN COMPOUNDS
ORGANIC COMPOUNDS
OXYGEN COMPOUNDS
PHOTOGRAPHY
SHOCK WAVES
SPECTRA
SPECTROSCOPY
450100* - Military Technology
Weaponry
& National Defense- Chemical Explosions & Explosives
400800 - Combustion
Pyrolysis
& High-Temperature Chemistry