A study of the near-critical state of metals by the passage of high currents through wires

The phenomena accompanying the passage of currents with densities j approx-gt 1011 A/m2 through metal wires have been investigated recently in connection with the possibility of studying high-temperature states of metals. During a short period of time the wire (or foil) materials passes through the entire spectrum of states from solid plasma. The rapidity of the process practically eliminates undesirable effects caused by interaction with the external medium. In addition, it can be considered reliably established that, prior to the loss of metallic conductivity, it is possible to achieve homogeneity of the wire material during its heating by the current. For this it is necessary to pass a current density higher than a certain critical value so as to ensure that the heating processes are dominant over the growth of magnetohydrodynamic (MHD) instabilities. From the standpoint of studying the high-temperature behavior of metals, however, the region of greatest interest is the region beyond the existence limits of metallic conductivity. In the stage when the wire is being destroyed by the current and a sharp increase in its resistance is observed, it is possible to reach near-critical or even critical states of matter. Here, the possibility of using the electrical explosion of wires to study the properties of liquid metals in the near-critical region is analyzed. It is shown that the uniformity of the heating of the condensed wire by a current is an important question in all stages of electrical explosion except in the plasma region. Values are obtained for the densities of Cu, Al, W, and Ni in the critical region