Helical field-driven translational-rotational conversion in conductors

A theory of a new magnetodynamic effect describing the energy exchange between the degrees of freedom of a conducting cylinder moving in a helical magnetic field has been developed. The possibility of effectively converting the translational motion of the cylinder into its angular rotation around the system axis [translational-rotational conversion (TRC)] has been demonstrated. A connection between this effect and the formation of helical trajectories of electrons in undulators in free-electron lasers and the inverse Faraday effect has been revealed. In TRC, unlike many known effects associated with the interaction of a moving conductor with a magnetic field, the conductor has no electrical contact with any external circuit, which makes it especially attractive for various applications. The TRC is also possible in a magnetohydrodynamic flow moving along the axis of a helical magnetic field. The theory is formulated in the limit of large magnetic Reynolds numbers, which corresponds to a sufficiently fast motion of well-conducting objects. In this scenario, the dynamics of the system is described by a nonlinear pendulum equation or a nonlinear pendulum equation with a nonzero right-hand side. In the latter case, a system dynamic mode corresponding to phase lock can be implemented.