Sensitivity of the diamagnetic sensor measurements of ITER to error sources and their compensation

The present paper is focused on the sensitivity analysis of the diamagnetic sensor measurements of ITER against several kinds of error sources, with the aim of compensating them for improving the accuracy in the evaluation of the energy confinement time and poloidal beta, via Shafranov formula.The virtual values of measurements at the diamagnetic sensors were simulated by the COMPFLUX code, a numerical code able to compute the field and flux values generated in a prescribed set of output points from massive conductors and generalized filamentary currents (with an arbitrary 3D shape and a negligible cross section) in the presence of magnetic materials. The major issue to face with has been to determine the possible deformations of sensors and electromagnetic sources. The analysis has been carried out considering the following cases:. -deformed sensors and ideal EM (electromagnetic) sources;-ideal sensors and perturbed EM sources;-both sensors and EM sources perturbed. As regards the compensation, several formulas have been proposed, based on the measurements carried out by the compensation coils; they basically use the value of the flux density measured to compensate the effects of the poloidal eddy currents induced in the conducting structures surrounding the plasma.The static deviation due to sensor manufacturing and positioning errors has been evaluated, and most of the pollution of the diamagnetic flux has been compensated, meeting the prescribed specifications and tolerances