Strata formation at fast electrical explosion of cylindrical conductors

The process of electrical explosion of aluminum and tungsten wires at current densities above $10^8$ A/cm$^2$ (the fast electrical explosion regime) is investigated. Within the frame of 2D magnetohydrodynamic calculations based on the Particle-in-Cell technique with realistic equations of state of the metals, the processes of strata formation in the plasma are considered. In the fast electrical explosion regime, strata formation is shown to take place due to the overheat instability. The strata occurrence is caused by the character of the conductivity change near the critical point of the liquid-vapor phase transition, that is, by metal conductivity decrease with a temperature increase and a density decrease. To provoke strata formation, the energy deposited into the wire substance should be of about the sublimation energy.