Continuous Oscillographic Method for Measuring the Velocity and Conductivity of Stable and Transient Shocks in Solid Cast Explosives

The continuous monitoring of the position and relative conductivity of reactive shock waves in confined cast explosives is made possible by a new technique. A fine Nichrome wire is cast within and parallel to the long axis of the sample. A record of its resistance during detonation serves to locate the ionization front associated with detonation. The measurement is recorded on an oscillograph. From the photograph of this record, instantaneous detonation velocities are measured to within ±2%. Attenuation of the initiating shock causes a delay in the establishment of a stable detonation in the acceptor. The distance and time required for this transition is confined charges can be measured. The simultaneous use of independent Nichrome and copper wire sensors furnishes additional information about the conductivity of the predetonation zone. Failure of a propagating detonation can also be studied; this permits the measurement of critical diameters, i.e., that diameter below which detonation will not propagate in an unconfined charge. Examples of each use are presented.