Hot spot mechanism

Sonochemistry is strongly affected by a variety of external variables, including acoustic frequency, acoustic intensity, bulk temperature, static pressure, ambient gas, and solvent (47). These are the important parameters which need consideration in the effective appHcation of ultrasound to chemical reactions. The origin of these influences is easily understood in terms of the hot-spot mechanism of sonochemistry. 

Impact and Friction Initiation of PETN have been extensively studied. This general subject is summarized in Bowden Yoffe (Refs 13 19), Afanas ev Bobolev (Ref 85a), and Vol 7, 135—55, which contains a rather complete description of impact initiation with many refs to the impact and friction initiation of PETN. There is general agreement that impact and friction initiation proceed via a hot spot mechanism (see Vol 7, HI 70—75). There is, however, considerable doubt and controversy about the mechanisms of hot spot formation... 

The hot spot mechanism is particularly important in systems near the detonability limits, and in maintaining detonation at relatively low velocity and low energy-release rate. The hot spots appear to supplement the Hugoniot energy by concentrating the temperature effect of the compression within small portions of the just-compressed layer as to initiate self-heating at these points, and decrease the need for thermal energy from other sources (Ref 34)... 

The voids or density discontinuities in a heterogeneous explosive cause irregularities of the mass flow when shocked. The heterogeneous explosive is initiated by local hot spots formed in it by shock interactions with density discontinuities. The hot spot mechanism is important in the propagation and failure of the detonation wave. As shown in Chapter 1, the density discontinuities are also a dominant feature of the heterogeneous explosive reaction zone. 

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