Polarization properties of dielectronic satellite lines in the K-shell x-ray spectra of B-like Fe XXII

We report the results of a combined theoretical and experimental study of B-like dielectronic recombination satellite lines excited by an electron beam. Polarization sensitive spectra were accumulated at the Lawrence Livermore electron beam ion trap facility. Three beam energies were chosen in the region of maximum B-like Fe satellite emission. At each energy, spectra were obtained using two LiF crystals of differing polarization sensitivities. Polarization-dependent spectra have been calculated using the degree of polarization of single lines computed with a photon density matrix formalism. The agreement between the experiment and theory is very good. Two spectral features were observed to have polarizations that were particularly sensitive to the electron beam energy. Spectral features with this property are candidates as diagnostics of energy and direction of electron beams in plasmas.