Measurements of absolute electron capture cross sections in He 2+ –He and Ne 8+ –O 2 , N 2 , CH 4 collisions

The total absolute cross sections of single- and double-electron capture (SEC and DEC) in the collisions of He 2+ with He and Ne 8+ with O 2 , N 2 , and CH 4 were studied in the energy ranges 3.5–50 keV/u and 2.8–40 keV/u, respectively. Through a deep analysis of the experimental systematic uncertainties in the measurement procedure and data evaluation, the error in the experimental results of the SEC cross sections is less than 9%. Within the uncertainties, the present results of the He 2+ –He collision show good consistency with previous measurements, validating the experimental system and paving the way for precise measurements of EC cross sections for a variety of ions and neutral gases. The present measurements allow for a test of EC theory and provide crucial EC cross section data for the establishment of plasma models in fusion research and astrophysical X-ray studies.