Motional-Stark spectroscopy is a powerful diagnostic for determining the magnetic field distribution in the plasma core, especially when heating systems such as Neutral Beam Heating and Electron Cyclotron Resonance Heating are used, as they can locally change the magnetic field. A spectroscopic system has been installed on TCV to measure the D_alpha emission. The magnetic field is obtained by performing a least-squares optimization method on the measured D_alpha emission with a theoretical model that considers Motional-Stark effect, with the poloidal magnetic field as a free parameter.
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