Gamma irradiation testing of prototype ITER in-vessel magnetic pick-up coils

To fulfill the requirements for ITER in-vessel magnetic diagnostics, several coil prototypes have beendeveloped, aiming at minimizing the disturbing effects of temperature gradients and radiation inducedphenomena. As a first step in the radiation resistance testing of these prototypes, an in-situ high doserate gamma radiation test on a selection of prototypes was performed. The aim of this test was to get afirst experimental feedback regarding the behavior of the pick-up coil prototypes under radiation. Fiveprototypes (a coil wound with glass-insulated copper wire, two LTCC coils and two HTCC coils) wereirradiated at a dose rate of 46 kGy/h up to a total dose of 72 MGy and at a temperature of 50◦C. Duringthe irradiation, the continuity resistances and the insulation resistances were continuously measured.Before and after irradiation reference data were recorded as a function of temperature (from 30◦C to130◦C). This paper includes the results of the temperature and irradiation tests and a discussion of thebehavior of the prototype coils in terms of electrical and mechanical properties.