Absolute cross sections of single and double electron capture for C ⁴⁺ colliding with He, O ₂ , N ₂ , and CH ₄

Context . Charge exchange between solar wind C 4+ ions and neutrals drives soft X-ray and extreme ultraviolet emissions in astrophysical environments. Laboratory studies of charge exchange processes provide accurate atomic structure parameters, which are essential for the modeling of astrophysical plasmas. Aims . We aim to measure the absolute charge exchange cross section of C 4+ colliding with He, O 2 , N 2 , and CH 4 for their potential applications in astrophysical plasma modeling, as such processes take place between fast solar wind and neutral gases in planetary atmospheres. Methods . The experiments were performed on a 150 kV highly charged ion collision apparatus at Fudan University. The C 4+ ions were generated from a 14.5 GHz electron cyclotron resonance ion source, collided with the target gas in the gas cell, and detected by a position-sensitive detector. We utilized the growth rate approach to investigate the electron capture cross section data. Results . We provide new absolute electron capture cross section data of C 4+ colliding with He, O 2 , N 2 , and CH 4 in the energy range of 2.3–33.3 keV/u or 671–2535 km/s, with experimental uncertainties of 9% and 10% for single- and double-electron capture, respectively. The measured single-electron capture cross sections for C 4+ +He show significant deviations from existing theoretical calculations. Conclusions. We obtained the absolute single- and double-electron capture cross sections of C 4+ colliding with He, O 2 , N 2 , and CH 4 . These new data significantly deviate from the predictions of current modeling approaches.