Radiance line ratios Ly-β/Ly-α, Ly-γ/Ly-α, Ly-δ/Ly-α, and Ly-ε/Ly-α for soft X-ray emissions following charge exchange between C6+ and Kr

Abstract

The radiance line ratios Ly-b/Ly-a, Ly-c/Ly-a, Ly-d/Ly-a, and Ly-e/Ly-a for soft X-ray emission following charge exchange (CX) between C 6+ and Kr are reported for collision energies between approximately 320 and 46,000 eV/u. The corresponding collision velocities (250-3000 km/s) are characteristic of the solar wind. X-ray spectra were obtained at the Oak Ridge National Laboratory Multicharged Ion Research Facility using a microcalorimeter X-ray detector with a resolution on the order of 10 eV FWHM. The measured Ly-e/Ly-a is zero for all considered energies and suggests that very little, if any, capture to 6p occurs. The measured Ly-b/Ly-a and Ly-c/Ly-a ratios intersect and form a well resolved node around (950 ± 50) km/s, which could be used as an astrophysical velocity indicative tool. The results reported here are compared to calculations for C 6+ + H since no published theory for C 6+ + Kr is known to exist. Double-electron-capture (DEC) and other multi-electron processes are possible. True double capture is estimated to be only 10% of the single-electron-capture (SEC).

Uncertainties in Atomic Data for Modeling Astrophysical Charge Exchange Plasmas

“…In Figure 5, we plot the comparison of the line ratio calculations and experiments for C VI and O VIII. The experimental data are taken from the beam-gas measurements by Andrianarijaona et al [75] for C VI and Seely et al [76] for O VIII. A caveat of the comparison is that these experiments used the Kr atom as a target, while the original theoretical calculations are based on capture from H atom.…”

“…Comparison of experimental and theoretical line ratios for the C 6+ (left) and O 8+ (right) reactions. The experimental data from Andrianarijaona et al[75] and Seely et al[76] are plotted as data points, and the predictions from G16, MCLZ, and RCMD are shown in black, red, and blue curves. The dashed curves show the calculations of C 6+ and O 8+ collisions with H atoms, and the solid lines show the collisions with Kr atoms obtained using the scaling of Leung & Kirchner[77].…”

Uncertainties in Atomic Data for Modeling Astrophysical Charge Exchange Plasmas

“…In Figure 5 we plot the comparison of the line ratio calculations and experiments for C VI and O VIII. The experimental data are taken from the beam-gas measurements by Andrianarijaona et al [77] for C VI and Seely et al [78] for O VIII. A caveat of the comparison is that these experiments used Kr atom as a target while the original theoretical calculations are based on capture from H atom.…”

“…Comparison of experimental and theoretical line ratios for the C 6+ (left) and O 8+ (right) reactions. The experimental data from Andrianarijaona et al[77] and Seely et al[78] are plotted as data points, and the predictions from G16, MCLZ, and RCMD are shown in black, red, and blue curves. The dashed curves show the calculations of C 6+ and O 8+…”