Skin Effect from Extended Irreversible Thermodynamics Perspective

Abstract

The skin effect is rediscussed from the point of view of extended irreversible thermodynamics. Within that framework, the current density flowing in a good conductor is assumed to relax in a finite time τ. For the whole frequency range, it is found that the skin effect is characterized by two length scales: the penetration depth δ and an oscillation scale ξ. Accordingly, it is also shown that the skin effect exhibits two sharply distinct regimes: damped oscillation and pure attenuation in space. A transition frequency between those regimes is determined by ω_t = 1/τ√3, thus leading to the possibility of measuring τ. In the high frequency regime, the penetration depth, as well as other related quantities, all acquire finite saturated values, which do not depend on the wave frequency and are determined by τ only. Experimental verification of the results presented here may be relevant in several branches of applied physics and engineering.