In order to confine the plasma within a “Tokamak” a current must be induced in the plasma in the toroidal direction. The toroidal current generates the poloidal magnetic field. The intensity of the toroidal plasma current strongly influences the confining and stability properties of the overall magnetic field configuration. JET is presently the only machine in the world able to operate with plasma currents above 5,000,000 amperes. Recent operations of JET have investigated plasma scenarios with toroidal plasma currents up to 3,500,000 amperes in preparation for performing experiments at even higher currents. Operation at high current requires careful assessment of the forces induced by this current in the in-vessel components.
Since fusion power increases with plasma current, ITER has been designed to operate with a toroidal current of up to 17,000,000 amperes. Therefore, high current experiments in JET give valuable input in preparing for the operation of ITER .