Ion-molecule collision processes relevant to fusion edge plasmas

A survey is presented on the existing database for ion-molecule collision processes relevant to fusion edge plasmas. The scope of the survey is limited to hydrogen and helium species, which form the main plasma constituents. In accordance with the energy range of interest (about 1-200 eV), the data have been mainly collected from low energy beam experiments. The experimental methods used are briefly discussed and characterized with respect to their strengths and weaknesses. The survey of data is divided into the following categories: (1) reactive collisions, with total cross-sections, state selective measurements and product distributions; (2) energy transfer collisions; and (3) negative ion collisions. Conclusions are drawn with regard to further work to be done on this subject.