Experimental profile of the stark broadening of the allowed and forbidden transitions in He I 4477 Å

Detailed measurements have been made of the profile of the line He I 4471 Å in a new type shock tube for electron densities in the range of 0.1 to 2 10¹⁶ cm^-3. The electron density in the plasma was found from the broadening of H_β, and Mach-Zehnder, interferometer, while the temperature was determined from the ratio of the intensity of He I 5876 Å to that of He II 4686 Å. The measured profiles are compared with two calculations based on the quasi-static approximation and non-adiabatic ion dynamic broadening to account for the perturbing ions. The relative intensities and the shapes of the allowed and forbidden components are in agreement with computed profile. (author)