Observation of an ion effect in the profile of the 4471-Å line of Hei

We have measured the profile of the 4471-{} line of Hei at electron densities nₑ=3×10¹⁵, 10¹⁶, and 3×10¹⁶ cm^-3 in plasmas of different chemical composition. We have observed a smearing of the central dip of the line varying with the inverse square root of the reduced mass of the radiator-perturber system. A comparison with a calculation using ion dynamics at nₑ=3×10¹⁵ cm^-3 shows a better agreement for the dip intensity than with the usual quasistatic ion calculations.