Proximity effect in a thin two-layer tubular conductor caused by a parallel filament

In this paper, we determine in a closed form the current distribution thin two-layer tubular conductor with sinusoidal presence of filament an equal but opposite current. The method treating problem consists solving integral equation for density one layer which enables to find other by imposing equality tangential components electric fields at interface. An important factor, AC DC resistance ratio is also found form. Some numerical examples, and ratio, versus frequency or geometry parameters, are presented.