Analysis of the Faraday and the Cotton-Mouton effects interaction in a tokamak plasma

Polarimetry, based on the measurement of the Faraday and the Cotton-Mouton effects, gives an important information on thermonuclear plasma density and current value. However at high plasma density and current conditions both effects start combine nonlinearly and it is difficult to obtain pure Faraday rotation angle and Cotton-Mouton phase shift angle. The paper presents an estimation of this interaction for various plasma regimes, typical for modern tokamak devices. The accuracy of the model, taking into account the coupling between the Faraday and the Cotton-Mouton when both effects are equal, is analyzed for the vertical beam path in the magnetized plasma.