Possibility of measuring the plasma main ion mass by plasma polarimetry in tokamak similarity experiments

Abstract

In the context of tokamak diagnostics, and considering a geometry involving line of sights inserted in a poloidal plane, The polarimetry measurements, i.e. the Faraday rotation and Cotton-Mouton ellipticity are very useful because they give quantitative evaluations of the poloidal magnetic field and plasma density respectively. In certain conditions, i.e. in plasma similarity experiments, they can give information on the plasma ion mass and this could be surprising being the polarimetry derived by anisotropy of the index of refraction which is a property related mainly to the electron dynamics. These conditions are verified when similarity experiments are done changing the mass of the main ion. The subject of this paper is the demonstration that indeed the polarimetry measurements depend on the ion mass and this can be detected with the present technology.