TJ-II: Calibration of the helical arrays of Mirnov coils: Difference between revisions

The calibration of the recently commissioned arrays of Mirnov coils has been performed by comparing the vacuum magnetic field of the standard configuration to the measurements of the integrated field obtained by each of the coils. Reproducibility is very good but only one magnetic configuration has been used and thus the calibration is sensitive to any error in the modelling of the theoretical field used for comparison. To ensure that this calibration, which is essential to correctly determine the mode numbers of the MHD perturbations, is correct, it is worthwhile to perform this exercise for different magnetic field distributions inside the device, either constructed by using other configurations or by preparing specific shots using the different CC, VF or HSX conductors separately. This proposal does not require the creation of plasma and can be executed at the beginning of the day previous to the plasma operation.