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

Following a review of earlier measurements and calculations of the Stark broadening of the Balmer-α line in plasmas of electron and ion densities from 108 — 1018 cm—3, recent measurements and various theoretical developments are discussed with emphasis on high densities up to Ne = 1019 cm—3 and temperatures up to kT = 10 eV. Although there is now fairly quantitative agreement between measured and calculated widths, shifts and profiles for Ne ≲ 1018 cm—3, serious disagreements are found beyond Ne ≈︂ 2 × 1018 cm—3. In particular, all calculations exhibit a stronger increase of widths with density than do the Bochum gas-liner pinch measurements, possibly indicating a loss of coherence in the quantum-mechanical interference between electron scattering on upper and lower levels of the line.