Eddy currents in the central column of the ETE spherical tokamak

This paper describes an analytical model of the eddy currents that circulate in the central column of the spherical tokamak ETE (Experimento Tokamak Esférico). The varying magnetic flux that forms and maintains the plasma current also induces currents in the copper bars of the toroidal field magnet central column, around which the ohmic heating solenoid was tightly wound. During the plasma startup phase the eddy currents strongly affect the performance of the ohmic heating system, and must be taken into account in the development of circuit models for the power system of ETE. Theoretical calculations of the ohmic solenoid impedance, including the eddy current and proximity effects, are compared with experimental values.