Line broadening by hot and dense plasmas

Abstract

This study is devoted to the broadening of hydrogenic x-ray lines emitted by plasmas produced by laser impact or implosion. In addition to the traditional broadening processes due to high- and low-frequency components of the electric microfield, we have examined the influence of the self-generated magnetic field $\overrightarrow{\mathrm{B}}$ correlated with the Doppler effect by the motional electric field ${\overrightarrow{\mathrm{E}}}_m={\overrightarrow{\mathrm{V}}}_E\times \frac{\overrightarrow{\mathrm{B}}}{c}$. For the interaction between plasma electrons and radiating ions with high charge number $Z_E$, fully quantum-mechanical results [Phys. Rev. A 19, 2421 (1979)] have been used to include all multipole orders of the Coulomb interaction. An analytical treatment of the combined effect of the ion microfield and the self-generated magnetic field shows clearly that the latter is quite important. Its influence consists principally in giving the line profiles a sensitive dependence on polarization and the observation direction $\overrightarrow{\mathrm{k}}$. In case of the C VI resonance line emitted from a plasma corresponding to the critical density in glass laser experiments and a magnetic field of about 10 MG, the profiles are considerably broader than those deduced from only the particle fields. In addition, the profiles observed parallel to the magnetic field ($\frac{\overrightarrow{\mathrm{k}}}{\frac{}{\overrightarrow{\mathrm{B}}}}$) may show a central dip which cannot be ignored in a quantitative study of the line absorption properties.