TIEMF effect in ceramic coated cables

Our previous work on mineral insulated cables demonstrated the important voltages that can appear in some of the coils used in ITER magnetic diagnostics simply due to thermal gradients present from the beginning of operation. To explore alternative cables, a new type of ceramic coated wire has being studied. The two wires examined consist of Cu–Ni and SS 304 conductors covered with a thin ceramic coating. This should reduce cold working during fabrication. An improved technique has been used to measure TIEMF with a rather narrow thermal gradient and highly reduced noise, able to examine the fine structure due to inhomogeneities. For both cables, marked TIEMF effects still exist. Although their absolute magnitude is relatively similar there are important differences in structure. The implications for ITER cables and coils are discussed. The coated cables are compared with MI cables taking also into account insulation and mechanical reliability.