Influence of ion dynamics on the width and shift of isolated He I lines in plasmas. II.

Abstract

Stark widths and shifts of the He i 7065-, 6678-, 5016-, 4713-, and 3188-\AA{} lines are measured in hydrogen-helium plasma. A repetitively pulsed low-pressure arc is used as a plasma source, while the signal averaging technique is employed to record the line profiles. The electron densities in the range of (2.5\char21{}5.9)\ifmmode\times\else\texttimes\fi{}${10}^{15}$ ${\mathrm{cm}}^{\mathrm{\ensuremath{-}}3}$ are measured by 10.6-\ensuremath{\mu}m laser interferometry. The electron temperatures ranging from 19 300 to 23 600 K are determined from the ratio of the ${\mathrm{H}}_{\ensuremath{\gamma}}$ line intensity to the underlying continuum, while the gas temperatures from 5000 to 12 600 K are measured from the Doppler component of the He i line profiles. The experimental Stark widths and shifts are compared with the theoretical results obtained from the three sets of semiclassical calculations of Stark broadening parameters by using the quasistatic and ion-dynamic treatment of the ions. Inclusion of ion dynamics in the width and shift calculations improves the consistency in the comparison between the theory and the experiment and shows the systematic discrepancy between three semiclassical calculations. These results suggest the possibility of high precision electron-density diagnostics.