Application of the second-order moments of polarized hydrogen lines to the investigation of pressure broadening and the motional stark effect

We present direct applications of the previously investigated algebraic second-order moments of polarized hydrogen lines to the study of pressure broadening (by charged perturbers) and of the motional Stark effect. These problems are of relevant interest for the diagnostics of electric and magnetic fields in solar plasmas. Pressure broadening is investigated under the simple assumption that the charged perturbers produce an isotropic electric field following the Holtsmark distribution. The corresponding line width turns out to be a simple function of the transition levels. In the investigation of the motional Stark effect, it is assumed that the hydrogen atoms follow an isotropic, Maxwellian velocity distribution. It is found that the effect of the motional electric fields on the dispersion of the Stokes profiles is analogous to that of an effective magnetic field, B* = χB, where χ depends only on the transition levels and the plasma temperature, plus an additional line-dependent broadening mechanism that affects the intensity profile only.