Abstract
An account is given of experiments involving collisions of H+, H+ 2. and He+ ions with hydrogen and helium in the energy range 3–35 KeV. The construction of apparatus for producing suitable beams of ions is described and details presented of an accurate method for measuring charge exchange and ionization cross-sections. Curves showing values of these cross- sections are given and they are compared with the results of other workers where these are available. A method for measuring e/m values of secondary ions is also described.