Abstract
Charge-exchange has been recognized as a primary source of soft x-ray emission in many astrophysical outflow environments, including cometary and planetary exospheres impacted by solar wind. Some models have been setup by using different data collections of charge-exchange cross-sections. However, multiple electron transfer has not been included in these models. In this paper, we setup a charge exchange model with the inclusion of double-electron capture, and make a detailed investigation of this process on x-ray emissions of highly charged carbon, nitrogen, oxygen and neon ions by using available experimental cross-sections. We also study the effect of different n −selective cross-sections on soft x-ray emission by using available experimental n −distributions. This work reveals that double electron capture enhancement on line intensity is basically linearly proportional to the ratio of ion abundance in the solar wind. It is more obvious for soft x-rays from carbon ions (C4 +) in collision with CO2, and the enhancement on line intensity can be up to 53 per cent with typical ion abundances (ace observation) in solar wind. The synthetic spectra with parameters from the Ulysses mission for solar wind reveals velocity-dependence, target-dependence, as well as the non-negligible contribution from the double-electron capture.
Effects of Excitation Conditions on Line Intensity in Spectrochemical Analysis of Nitralloy