Polarization Spectroscopy of Ions

Spectropolarimetric effects in the linear spectrum of the optical emission are connected not only to the anisotropy of the fast exciting electrons or to the distribution of the resonance radiation but also to the anisotropy in the relative velocity space of the colliding atomic particles. In the last case, the anisotropic collisional relaxation within the system of the quantum states of the excited atomic particles plays an important role. Such anisotropic relaxation takes place under the collisional relaxation of the drifting ions with the neutral atomic particles. The present chapter is devoted to the description of the drift self-alignment of ions and the diagnostic applications of this effect for the ionized gas sensing.