Current Waves Generated by Detonation of an Explosive in a Magnetic Field

Abstract

The structure of the electromagnetic field in detonation of a condensed explosive in a magnetic field is analyzed qualitatively. Propagation of a detonation wave in a magnetic field leads to generation of an electric current in explosion products. The physical reason for current generation is the “freezing” of the magnetic field into the conducting substance at the detonation front and subsequent extension of the substance and the field in the unloading wave. The structure of the current layer depends on the character of the boundary magnetic fields and conditions on the surface of initiation of the explosive. Detonation of the explosive in an external magnetic field B₀ generates a system of two currents identical in magnitude but opposite in direction. The structure of the arising current and its absolute value are determined by the parameter R₁ = μ₀ σ₀D²t (μ₀ is the magnetic permeability of vacuum, σ₀ is the electrical conductivity of detonation products, D is the detonation‐front velocity, and t is the time). The value of the current increases with the detonation‐wave motion, and the linear current density is limited from above by 2B₀/μ₀. For R₁ ≫ 1, the electric field in the conducting layer is significantly nonuniform; for detonation products with a polytropic equation of state, a region of a constant‐density current is adjacent to thedetonation front. The results of this analysis are important for interpretation of experiments performed and development of new methods for studying the state of the substance in the detonation wave.