detonations

Detonation is a form of combustion in which a shock wave drives a self-sustained chemical reaction in a reactive medium. The detonation front is a nearly instantaneous, high-pressure rise that travels at supersonic speed, in contrast to deflagration where flames propagate subsonically by heat transfer. In a detonation, the leading shock compresses and heats the material, triggering rapid decomposition and formation of reaction products; the reaction zone that follows is typically very thin.

Detonation velocity, or the speed of the detonation front, depends on the material, density, temperature, and confinement. For many high explosives, velocities range from roughly 3 to 9 kilometers per second. The Chapman–Jouguet theory describes a self-sustaining detonation with a steady flow behind the front and provides relationships among velocity, pressure, and temperature. Detonation products are usually hot, highly pressurized gases, with significant overpressure contributing to the blast.

Materials capable of detonation include solid high explosives such as TNT, RDX, HMX, and PETN, as well as certain gaseous or vapor-phase mixtures like hydrogen–oxygen or acetylene–oxygen under suitable conditions. Detonation often requires confinement and sufficient density; the smallest diameter that can support a stable detonation is called the critical diameter. Initiation is achieved by boosters, strong shocks, or electric/electronic ignition systems.

Applications span mining and quarrying, demolition, and certain shaped-charge and armor-penetration technologies, as well as detonation-driven pulsed-power devices. Safety considerations focus on blast effects, containment integrity, accidental initiation, and proper handling and storage of energetic materials.