Plasma polarization spectroscopy

摘要: In the density matrix formalism, ensemble of atoms or ions is expressed in terms population and alignment excited levels ground state. The an level determines intensity emission line originating from this gives rise to linear polarization line. Spatially anisotropic collisions induce transitions between populations alignments; for example, along with a produced by beam electrons ground-state population. Thus, plasma produces polarized radiations, spectroscopy (PPS) we can investigate anisotropic, thus non-thermal, features plasma. angular distribution perturber velocities expanded Legendre polynomials. expansion coefficients relevant cross sections among alignments yield rate these transitions. For immersed plasma, coupled equations are constructed levels. We review present status our knowledge collision various processes. Several experimental observations PPS performed so far reviewed, which include those on tokamak laser plasmas, discharge plasmas solar flares. discuss what kind information could be obtained PPS.