Profile of Ionized-Calcium Lines in an Arc-Plasma Jet

Abstract

Profiles of the Ca ii resonance lines ($\ensuremath{\lambda}3934$ and $\ensuremath{\lambda}3968$) radiated from an arc-plasma jet were observed by means of a Fabry-Perot etalon. The measurement was made for electron densities 4.0\ifmmode\times\else\texttimes\fi{}${10}^{16}$ and 6.4\ifmmode\times\else\texttimes\fi{}${10}^{16}$ ${\mathrm{cm}}^{\ensuremath{-}3}$, and a temperature around 11 500 \ifmmode^\circ\else\textdegree\fi{}K. The lines exhibited Stark-effect broadening, full width at half-maximum 0.25\ifmmode\pm\else\textpm\fi{}0.06 and 0.51\ifmmode\pm\else\textpm\fi{}0.10 ${\mathrm{cm}}^{\ensuremath{-}1}$, respectively, which was accompanied by small violet shifts, +0.03\ifmmode\pm\else\textpm\fi{}0.02 and +0.10\ifmmode\pm\else\textpm\fi{}0.03 ${\mathrm{cm}}^{\ensuremath{-}1}$. The result can be interpreted by taking into account the effect of both strong and weak collisions of electrons disturbing the radiating process of the ion; the broadening is mainly contributed by strong collisions, while the shift can be explained to be due to weak collisions.