Stark width of 4p'[1/2]-4s[3/2](0) Ar I transition (696.543 nm)

The full width at half maximum (FWHM) of the 696.5 nm Ar I spectral line profiles was measured in the plasma. temperature range from 13 500 K to 24 000 K and free electron density from 1.2 to 2.0 x 10(23) m(-3). Results were obtained for this line emitted from the near-cathode region of an atmospheric pressure, 200 A arc burning in pure argon. Our results are compared with data existing up to now. In the electron density range of our experiment, the 696.543 nm Ar I line Stark FWHM is linearly proportional to the electron density. The observed dependence of the FWHM on the plasma temperature and electron density is in qualitative agreement with Griem's theory; however, the ratio of calculated and measured FWHM was equal to 1.55, for the dependence on electron density and temperature. The dependence of FWHM on electron density, obtained by weighted least squares fitting of all our data with the constraint that the curve passes through the origin, is well represented by the following equation: Delta lambda(S)(n(our data)) = (1 +/- 0.067) x 0.08 297 nm x (N-e/10(23) m(-3)), with Delta lambda(S)(n) in nm and N-e in m(-3) for the temperature T-n = 13 000 K.