The equilibrium state of bifilar helix as element of metamaterials

In the present article, we study the long bifilar helix in which electric currents are quasi-stationary, i.e. the wavelength of the electromagnetic field is much longer than the turn of the helix. All components of the force acting on a physically small element of one helix from the other helix having a big length are calculated. The case when the currents in the two helices have the same direction relative to the x axis is considered. The dependence of the radial component of the force of interaction between two helices on the pitch angle is determined. At various pitch angles the helices can attract and repel each other while the direction of the current does not change. It is found the value of pitch angle when two helices do not interact and bifilar helix, formed by them, is in equilibrium state.