Refurbishment of JET magnetic diagnostics

In a tokamak device, magnetic diagnostics play a key role in: (i) the understanding of plasma physics, (ii) control and (iii) safe operation (Ariola and Pironti [1]). JET plasmas have magnetic fluctuations from a large variety of MHD instabilities (Wesson, 2000) and is equipped with fast magnetic Mirnov coils (Giovannozzi et al., 2014; Nave et al., 2004; Heeter et al., 2000) for spectral and mode number analysis. By the end of 2016 (end of experimental campaign C36B), JET had lost almost all pick-up coils used for MHD analysis (fast Mirnov coils). In order to restore the JET MHD modes analysis capability for the coming DT campaign, 25 + 2 faulty in-vessel coils were refurbished. A new coil design was implemented to try to diminish the failure rate, mitigating the possible cause that led to those failures. New sensors will use GLIDCOP® (Boyer et al., 2015) wire and will be remotely-handleable (RH) compatible.