A. G. Ivanov

Electromotive force produced by shock compression of a substance

The phenomena accompanying shock polarization of linear dielectrics and depolarization of nonlinear dielectrics are considered. It is established that the appearance of an emf on the front of a shock wave is a characteristic of a large class of substances, such as linear and nonlinear dielectrics, semiconductors, and metals. It is shown that the emf produced by shock compression of ionic crystals, polar dielectrics, semiconductors, and a number of metals is due to shock polarization. Diffusion of carriers from the front of a shock wave is observed in shock-compressed bismuth, europium, and aluminum. Shock compression of polarization nonlinear dielectrics leads to a stronger effect, namely to the onset of a depolarization emf. The presented phenomenological description of shock polarization is in good agreement with experiment.

Explosion-Assisted Blockage f Gas- or Liquid-Filled Steel Pipelines

New experimental data on explosion-assisted blockage of gas- or water-filled steel pipelines of various standard sizes with a 5–7 % relative wall thickness and diameters up to 424 mm are reported. The data show a considerable potential of the method. It is shown that a twentyfold change in the pipeline dimensions, at a impactor-plate velocity of ≈ 200 m/sec, induces no specific features into the pipeline blockage behavior. In this case, the explosive consumption increases from 3 g to 3.5 kg, with no spalling or fractionation of the impactor-plate material and screens observed. Key words: explosives, pipeline blockage, gases and liquids.

POLARIZATION PROBE STUDY OF THE INITIATION OF DETONATION IN AN EXPLOSIVE BY SHOCK WAVES

It has been shown [1-3] that electrical polarization of an explosive substance during shock compression, that is, shock polarization, is a source of information on the physical and chemical transformations of the explosive behind the shock and detonation fronts. When the detonation is triggered by a shock wave of amplitude p less than the Jouguet pressure pj, it is possible to determine the moment the detonation begins and its delay time T d [3] from an oscilloscope trace of the polarization current I(t). However, from the quantitative standpoint the results of [3] are rather uncertain, since the values of rd found for hexolite had a large scatter, >50%, and the sign of the initial jump in the polarization current, Io [Io = I(to)], where to is the moment the shock wave arrives at the sample,* changed from sample to sample for p = const.