Measurements of turbulent magnetic diffusivity in a liquid-gallium flow

Direct measurements of the effective conductivity (magnetic diffusivity) in the turbulent flow of a liquid metal have been performed. An nonstationary turbulent flow of a gallium alloy has been excited in a closed toroidal channel with dielectric walls. The Reynolds number reaches a maximum value of Re ≈ 10⁶, which corresponds to the magnetic Reynolds number Rm ≈ 1. The conductivity of the metal in the channel has been determined from the phase shift of forced harmonic oscillations in a series RLC circuit whose inductance is a toroidal coil wound around the channel. The maximum deviation of the effective conductivity of the turbulent medium from the ohmic conductivity of the metal is about 1%.