ITER in-vessel magnetic sensors prototyping and tests

The ITER in-vessel equilibrium magnetic sensors will be installed in a hostile environment having severe neutron irradiation and cyclic heat loads which could cause undesired effects that can compromise the accuracy of the measurements. The paper describes the design, construction and test of a new set of in-vessel pick-up coil prototypes for ITER developed with the aim at reducing the spurious electromotive forces due to transverse magnetic area and to internal thermal gradients while guaranteeing the required radiation hardness. The sensors have been subjected to various tests including: mechanical, electrical, magnetic and thermal characterization, micrographic analysis and vacuum out-gassing in ITER relevant conditions. In addition, specific tests have been designed for the measurement of the thermally induced electromotive force. The paper will present the development of the sensors and the results obtained.