Stark broadening of the He I 492.2 nm line with forbidden components in dense low-temperature plasma

•We tested computer simulation calculations of the He I 492.2 nm line shapes.•Simultaneous fitting of discharge spectra with He I lines and hydrogen H beta for plasma diagnostics purpose.•Simple program for simultaneous fitting of several line profiles in the form of data tables developed.•Simulation recommended for high electron density plasma diagnostics.

We present the results of an experimental study of the He I 492.2 nm line with forbidden components emitted by low-electron temperature and high electron number density helium plasma with or without addition of hydrogen. The shapes of the He I 447.1 nm and 501.6 nm lines and hydrogen Hβ line were used to measure electron number density in the range (1-5)×1023 m−3, while electron temperatures in the range from 25,000 K to 35,000 K were determined from the line to underlying continuum ratio of He I lines at 388.8, 667.8, 706.5 and 728.1 nm. The experimental profiles of the He I lines are compared with the results of a computer simulation method. The comparison was performed by use of a program for simultaneous interpolation of data tables obtained by computer simulation for 492.2 and 501.6 nm He I and hydrogen Hβ lines. The electron number densities obtained from this comparison agree within 10% with corresponding values determined from the 447.1 nm He I line which is well within theoretical and experimental uncertainties for all lines included in comparison.