Abstract
It is suggested that the poloidal magnetic field in a tokamak may be deduced from the analysis of circular polarization of light impurity ion lines excited by charge-exchange recombination. Visible or near-ultraviolet transitions in hydrogenlike oxygen and carbon are considered. Estimations of the linewidths and the magnitude of the Zeeman effect show that, with appropriate polarization analyzer and the experiment geometry, the poloidal component of the magnetic field can, in principle, be measured. Uncertainties of the model used to calculate the polarized line profiles do not affect the interpretation of the measurement in a fundamental way and may be accounted for experimentally by calibrating the polarization effect against the components of the toroidal field. In principle, the analysis of only one transition may provide information about the whole poloidal field profile.