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Experiments were performed in which confined samples of TATB were initiated by uniform and rapid energy deposition via a penetrating electron beam. The temperature and pressure were obtained in the exothermic region with a resolution of about 2 ms. Information on reaction kinetics was obtained to very high temperatures (≳1000 °C) and pressures (≳ 3000 psi). The absence of thermal gradients greatly simplifies the analysis. Values were obtained for the thermal initiation threshold, the explosion temperature, and kinetic parameters for a consistent reaction below 380 °C. An observed endothermic reaction near 390 °C was shown to be due to an impurity. Non-Arrhenius behavior was observed at higher temperatures. A very fast rise in the reaction rate just above 400 °C is followed by a rapid fall off from extrapolated values at higher temperatures.

Recently, it has been shown that an initial cloud of particles advected by a fluid may, under common circumstances (e.g., when the particles float on the fluid surface), eventually becomes distributed on a fractal set in space. This paper considers the characterization of such fractal spatial patterns by wave number spectra. If a scaling range exists in which the spectrum has an observable power law dependence, k−ρ, then the exponent ρ is given by ρ=D2+1−M, where D2 is the correlation dimension of the fractal attractor and M is the dimension of the relevant space. We find that observability of the power law may be obscured by fluctuations in the k-spectrum, but that averaging can be employed to compensate for this. Theoretical results and supporting numerical computations utilizing a random map are presented. In the companion paper by Sommerer [Phys. Fluids 8, 2441 (1996)], an experimental example utilizing particles floating on the surface of a flowing fluid is given. (More generally we note that our result for the k-spectrum power law exponent ρ should apply to fractal patterns in other physical contexts.)

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