ISTTOK poloidal field coils positioning assessment

The construction of any machine have inherent structural assembling errors. With aging and stresses these tend to increase and can particularly deform the original structures leading to significant deviations from original designs. To assess ISTTOK poloidal coils fixtures after almost 30 years of operation at IST, Lisbon a series of tests were conducted. Due to its inherent robustness and reliability, the magnetic diagnostic is the prime candidate for real-time plasma position control applications. ISTTOK is equipped with a set of digital integrators for magnetic reconstruction in line with W7-X and in the future with ITER. Incoherence in the data analysis of the poloidal Mirnov coils array suggested a misalignment of the poloidal field (PF) coils. This contribution explores this possibility, relying on the analysis of the magnetic diagnostic data in order to determine the magnetic position of the PF coil circuits. A significant deviation on the positions of said coils was found and a back-propagated correction based on vacuum measurements is proposed for future magnetic data analysis both for real-time control applications and equilibrium reconstruction codes.