Calculated profiles of H I lines of interest for solar plasma electric field measurements
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- Casini, R. & Foukal, P. Sol Phys (1996) 163: 65. doi:10.1007/BF00165456
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We present calculated Stark-polarized line profiles for a number of H i lines observed in the visible and infrared emission spectrum of solar prominences and other limb activity. For use in measurements of possible electric fields in these structures, we also calculate curves giving the difference in line width between the 1/2 (I ± Q) profiles as a function of electric-field intensity. Our calculations take into account magnetic fields in these structures, and incorporate typical observed values of Doppler broadening. These calculations explicitly consider the H i fine structure neglected in previous work, and thus are more accurate in the range of low to intermediate electric-field intensity likely to be encountered in solar plasmas (E < 103 V cm−1). Our results enable us to compare behavior when E and B are parallel, or perpendicular. We draw particular attention to the high electric-field sensitivity of the transitions between high levels such as 12–8 and 15–9 in H i, observed in prominences at wavelengths around 11μ. Their sensitivity is roughly an order of magnitude larger than that of the high Paschen-series lines used in solar plasma electric field studies so far.