The first measurement of the In III Stark widths

The shapes of 16 doubly ionized indium (In III) spectral lines have been measured in the laboratory helium plasma at 13,000 K electron temperature and 1.48 × 1023 m− 3 electron density. At mentioned plasma conditions the Stark broadening has been found as the dominant mechanism in the line shape formation. Here presented data are the first reported values for Stark widths (W) related to the specific In III lines. The modified version of the linear, low-pressure, pulsed arc was used as a plasma source operated in helium with indium atoms, as impurities, evaporated from indium cylindrical plates located in the homogenous part of the discharge, providing conditions free of self-absorption. At the above mentioned helium plasma conditions we have found symmetrical In III line profiles of the Voigt type. This means that the expected hyperfine structure splitting (Δhfs) in the investigated In III lines has been overpowered by Stark and Doppler broadening. We recommend the found W values of the intense and well isolated 298.280, 403.232 and 524.877 nm In III lines for the plasma electron density diagnostic ranged between 1021 m− 3 and 1023 m− 3.