Stark Broadening of Hydrogen Spectral Lines in Strongly Coupled Plasmas: Effect of the Electrostatic Plasma Turbulence at the Thermal Level

In 2014, Kielkopf and Allard (KA) performed a benchmark experiment where they measured the Full Width at Half Maximum (FWHM) of the Hα line at the electron densities Ne by two orders of magnitude greater than the corresponding previous benchmark experiments, namely up to Ne = 1.4 × 10 20 cm-3. No theoretical calculations of the FWHM of the Hα line existed in this range of Ne. In the present paper we present an analytical theory adequate for the range of the electron densities reached in KA experiment. In this range of Ne, a new factor becomes significant: a rising contribution of the Electrostatic Plasma Turbulence (EPT) at the thermal level of its energy density. After taking into account this contribution, which turns out to be comparable to the corresponding contribution by electron and ion microfields in this range of Ne, our theoretical FWHM of the Hα line becomes in a very good agreement with the experimental FWHM of the Hα line by KA in the entire range of their electron densities. We also extrapolate the FWHM of the Hα line from the Gigosos-Cardenoso tables, which were produced by the most advanced simulations, but without allowing for the thermal EPT: this leads to the underestimation of the experimental FWHM by up to 25%. Stark profiles and the FWHM of other hydrogen spectral lines can also be calculated by the present theory. PACS numbers: 32.70.Jz, 32, 60.+i, 52.35.Fp, 52.70.Kz