Plasma effects in the spectrum of high Balmer lines

Measurements of high Balmer lines (N_upper = 12 to 19) emitted from a hydrogen discharge of relatively low plasma density show that the spectrum may be well reproduced by a superposition of symmetric Stark profiles, which accounts for the broadening effect generated by ions and quasistatic electrons. The small deviations which were found most probably involve inelastic electron collisions connecting adjacent upper levels. Within experimental accuracy, a shift is not detectable either for odd or for even series members. This finding is inconsistent with the observations of other authors according to which odd Balmer lines are shifted to the red.