Electro-optical measurement of an induced toroidal electric field in water

An induced toroidal electric field is measured optically using a Pockel´s device. Multiple primary coils were used in inducing the field to avoid an increase in the primary voltage. A Bi₁₂SiO₂₀ crystal with a relative permittivity of 56 is used as the Pockel´s device. As the electric field inside the crystal is much smaller than that in air the electric field measurements were performed in water to increase the sensitivity. The phase shifts caused by Pockel´s effect are of the order of 10^-3-10^-2 rad and the measured values of induced electric field are 40 approximately 200 V/cm which agree with those calculated from one turn voltage to within about 20%.