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

Profiles of the Ca ii resonance lines ($\lambda 3934$ and $\lambda 3968$) radiated from an arc-plasma jet were observed by means of a Fabry-Perot etalon. The measurement was made for electron densities 4.0×${10}^{16}$ and 6.4×${10}^{16}$ ${\mathrm{cm}}^{-3\mathrm{}}$, and a temperature around 11 500 °K. The lines exhibited Stark-effect broadening, full width at half-maximum 0.25±0.06 and 0.51±0.10 ${\mathrm{cm}}^{-1\mathrm{}}$, respectively, which was accompanied by small violet shifts, +0.03±0.02 and +0.10±0.03 ${\mathrm{cm}}^{-1\mathrm{}}$. 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.