Revisiting the Stark Width and Shift of He II Pα

Abstract

We report experimental determination of plasma-induced Stark widths and shifts of the He II Pα line and a comparison of the results with calculations performed by several computational approaches. The measurements were carried out in a small compressing plasma channel device, reaching electron densities in excess of 10 18 cm −3 and temperatures of a few eV. The experimental data are in a good agreement with some previously published studies. However, the measured relation between the Stark shift and width could not be reproduced by either of the codes, and this disagreement is not yet resolved. This suggests the existence of an additional effect that is not accounted for in the present models and leads to a larger than expected Stark shift of the He II Pα line.

Beyond the Linear Stark Effect: A Retrospective

“…The comparison of obtained experimental data for the He II P α [186] with the previous ones has shown reasonable agreement. The several codes, described earlier elsewhere, were applied for the calculations of the shifts, related to the experimental plasma parameters: ST(Duan), MELS (Iglesias), SimU(Stambulchik) (see [186]).…”

“…Recently in 2018 Stollberg, Stambulchik, Duan, Gigosos, Herrero, Iglesias and Mossé published a paper with the new measurements of the width and shift of He II P α [186]. The comparison of obtained experimental data for the He II P α [186] with the previous ones has shown reasonable agreement.…”

“…Recently in 2018 Stollberg, Stambulchik, Duan, Gigosos, Herrero, Iglesias and Mossé published a paper with the new measurements of the width and shift of He II P α [186]. The comparison of obtained experimental data for the He II P α [186] with the previous ones has shown reasonable agreement. The several codes, described earlier elsewhere, were applied for the calculations of the shifts, related to the experimental plasma parameters: ST(Duan), MELS (Iglesias), SimU(Stambulchik) (see [186]).…”

Spectral Line Shapes in Plasmas II

“…The non-linear corrections are typically minor compared to the linewidths, which complicates the measurements. The new data of the He II Paschen-α width and shift, presented by Stollberg et al [11], are compared to calculations, and the observed width-shift relation appears to be inconsistent with the theoretical predictions. It is expected that further efforts-both on the experimental and theoretical sides-will put an end to the controversy.…”