No abstract

Small metal bridgewires are commonly used to ignite energetic powders such as pyrotechnics, propellants, and primary or secondary explosives. In this paper we describe a new means for igniting explosive materials using a semiconductor bridge (SCB). When driven with a short (20 μs), low-energy pulse (less than 3.5 mJ), the SCB produces a hot plasma that ignites explosives. The SCB, a heavily n-doped silicon film, typically 100 μm long by 380 μm wide by 2 μm thick, is 30 times smaller in volume than a conventional bridgewire. SCB devices produce a usable explosive output in a few tens of microseconds and operate at one-tenth the input energy of metal bridgewires. In spite of the low energies for ignition, SCB devices are explosively safe. We describe SCB processing and experiments evaluating SCB operation. Also discussed are the SCB vaporization process, plasma formation, optical spectra from the discharge, heat transfer mechanisms from the SCB to the explosive powders, and SCB device applications.

even though the absence of UV, visible, and near-IR absorptions makes it difficult to directly monitor this species spectroscopically.

We report the direct observation of several chemiluminescent product channels associated with the b ¡molecular reaction of C2H with_02. Spontaneous emission is detected from the nascent reaction products CH(A2A), CO(a,32+), and C02(X1Sg+,u3>l), and the rate coefficient for the removal of the C2H species which leads to the observed products (&R = (2.1 ± 0.3) X 10'11 cm3 molecule'1 s'1) is independent of the species being monitored, the C2H precursor, and the photolysis method (excimer laser at 193 nm, or IR multiple photon dissociation). Reaction is believed to proceed through a peroxy radical intermediate, which provides vibrational energy which can accelerate the nuclei toward the different product channels, and C2H vibrational excitation does not affect kR but is carried over into product degrees of freedom. The products which we observe require an interaction of the "terminal" oxygen atom with the carbon -electron system, and there are no apparent inversions or anomalies in the concentrations or internal state distributions of those species which we detect. It is quite possible that C2H(A1 2II) is the species responsible for the observed emissions.

Pulsed-laser-excited Raman scattering methods have been used to examine the dynamic molecular-level response of an explosive molecule (triaminotrinitrobenzene, TATB) to sustained shock loading at a fused silica window interface. The anomalous behavior of Raman modes associated with nitro groups in the molecule (the 881-cm"1 N02 deformation mode, the 1146-cm"1 symmetric C-N02 stretching mode, and the 1170-cm"1 totally symmetric N02 stretching mode) is compared to results obtained under static high pressure. The shock compression data indicate that elevated temperatures act to restrain pressure-enhanced coupling of N02 and NH2 groups in the molecule. Differences in the spectra obtained under static and dynamic high-pressure conditions are discussed in relation to the known insensitivity of TATB to shock initiation.