Experimental investigation of plasma-broadened hydrogen Balmer lines at low electron densities

Stark Broadening of the Hydrogen Balmer-α Line in Low and High Density Plasmas

“…7 of [41], with measurements down to N e = 4 × 10 14 cm −3 at electron temperatures near 1.5 eV (but lower "gas"-(atom-and ion-) temperatures). If fine structure, Doppler and instrumental broadening are accounted for, the excess broadening over ST calculations is only by a factor about 2 at low densities (rather than by the factor of 3 stated in [40], [41]), presumably due to ion-dynamical effects. Interestingly enough, the full computer simulations [31] yield in this case (after fine structure, etc., are allowed for) widths which are very similar to those measured by Ehrich and Kelleher [40], [41].…”

“…Returning briefly to measurements just below N e = 10 15 cm −3 , comparisons between H-α and D-α profiles from (mostly) helium arc plasmas [41] and helium θ-discharge plasmas [45] reveal conspicuous differences: at N e = 6× 10 14 cm −3 , Fig. 3a of [41] shows well-separated, mostly Doppler-broadened profiles; whereas at the same density, Fig.…”

“…Again, (helium) arc experiments [39]- [42] provided a large data set, as summarized in Fig. If fine structure, Doppler and instrumental broadening are accounted for, the excess broadening over ST calculations is only by a factor about 2 at low densities (rather than by the factor of 3 stated in [40], [41]), presumably due to ion-dynamical effects. If fine structure, Doppler and instrumental broadening are accounted for, the excess broadening over ST calculations is only by a factor about 2 at low densities (rather than by the factor of 3 stated in [40], [41]), presumably due to ion-dynamical effects.…”

“…(Note that the wavelength arrow in [41] is inverted.) The low temperatures in the arc experiment [41] explain why any ion-dynamical effects were found to be relatively small, while in the θ-discharge experiment [45] the measured profiles could be well-represented in terms of Voigt profiles with Lorentzian (Stark) profiles with FWHM widths of 0.50Å, or 0.44Å if the inhomogeneity correction was reduced by a factor of 2. The low temperatures in the arc experiment [41] explain why any ion-dynamical effects were found to be relatively small, while in the θ-discharge experiment [45] the measured profiles could be well-represented in terms of Voigt profiles with Lorentzian (Stark) profiles with FWHM widths of 0.50Å, or 0.44Å if the inhomogeneity correction was reduced by a factor of 2.…”

“…Again, (helium) arc experiments [39]- [42] provided a large data set, as summarized in Fig. 7 of [41], with measurements down to N e = 4 × 10 14 cm −3 at electron temperatures near 1.5 eV (but lower "gas"-(atom-and ion-) temperatures). If fine structure, Doppler and instrumental broadening are accounted for, the excess broadening over ST calculations is only by a factor about 2 at low densities (rather than by the factor of 3 stated in [40], [41]), presumably due to ion-dynamical effects.…”