Single and double electron capture by slow He2+ from atoms and molecules

Impact of slow alpha particles (He2+) on H2 and O2 is relevant for radiation cooling in future magnetically confined burning fusion plasmas. A new compact experimental setup has been utilized for measuring absolute cross sections for single (SEC) and double electron capture (DEC), and transfer ionization (TI) in collisions of slow (impact energy typically 0.1–1 keV times ion charge) singly and multiply charged ions with atoms and molecules. Our method combines collection of slow product ions and electrons with primary ion beam attenuation and stopping in a differentially pumped target gas chamber. Reliability of the new setup has been checked by measuring well established SEC and DEC cross sections for impact of slow singly and doubly charged noble gas ions on their atoms (He, Ne, Ar). We have then measured absolute cross sections for SEC by both 3He2+ and 4He2+ from Ne, and in further consequence will study fusion relevant SEC and DEC by He2+ from H2 and O2.