Numerical Calculation of Pick-Up Coils Frequency Response as a Useful Tool for Local Magnetic Field Sensors Design

The aim of this article is to present a useful numerical procedure suitable to accurately model pick-up probes for design-oriented purposes, reducing the required prototyping activity and allowing more accurate results with respect to analytic estimations, taking into account both inductive and capacitive effects in complex geometries. The proposed methodology is characterized by the following steps: 1) a partial element equivalent circuit (PEEC) formulation, speeded up by a parametric model order reduction (pMOR) technique, is used to efficiently model the probe in the frequency domain taking into account both inductive and capacitive effects; 2) a nonlinear least-squares solver is used to identify an equivalent RLC network describing the full behavior of the probe up to the first resonance frequency; and 3) a circuital model, considering the probe, the transmission line (TL), and the terminating impedance, is used to estimate the bandwidth of the complete system from the probe to the acquisition system. The experimental validation of the proposed method against the RFX-mod2 three-axis pick-up probe prototype is also presented, together with the application to the design of the magnetic sensors for the new Divertor tokamak test (DTT) facility.