Metals during rapid heating by dense currents

Heterogeneous Plasma‐Producing Structures at Current Implosion of a Wire Array

“…The specific power due to absorption of the emitted electrons is j s ∆ε/λ e ρ, where j s is the current density of emission, λ e is the absorption thickness and ρ is the metal density. For tungsten the current density of thermal emission j s varies very fast from 14 A/cm 2 at a temperature of 3000 K to 480 A/cm 2 at the temperature of melting [12]. The difference in energy counted from the initial temperature 300 K between these two states is much less than that at the temperature of melting, ∼1/5.…”

“…Possible mechanisms of such fast plasma formation are contributed to an anomalous electron emission at current densities j > 1 MA/cm 2 [12], gas desorption from the surface at a temperature of ∼700 K and a radial electric field [31]. The effect of the electrode polarity on the electric explosion of wires was demonstrated in [32], the comparison the characteristics of breakdown occurred in gas and along a thin tungsten wire are presented in [42].…”

“…Its maximum value calculated in terms of the voltage and current measured was always several times less, than the liner resistance at the tungsten melting temperature. The high conductivity can be easily explained by a shunting effect of a near-surface plasma [12]. A typical temporal dependence of the voltage U (t) on the axis and the current J(t) referred to a single wire is given in Fig.…”

“…There still exist an uncertain role of the electron emission at a fast Joule heat up in both arising a primary plasma on the wire surface [12,13] and subsequent producing of plasma from the products of electric wire implosion. As to the latter, natural energy sources to ionize a cold substance are: a thermal energy (transferred by heat conduction) of a plasma flux [11], an energy of pre-pinch radiation [15] and an energy of the electric field in the point of the wire location.…”

Neutral Copper Gas Resistivity Measurements by Means of an Exploding Wire in Air

“…It is a phenomenon long-known to science [2], and has subsequently been used in multiple scientific investigations [3][4][5]. Electrical energy absorbed by the exploding wire system until its transformation into plasma is a key characteristic in the further development of the phenomenon, as it influences the initial plasma state, prior to its last expansion [6] .…”