Our understanding of elementary processes in plasmas has been increasing dramatically over the last few years. The development of various swarm techniques, such as the temperature variable selected ion flow tube or the selected ion flow drift tube, has provided the prerequisite for detailed investigations into ion molecule reactions both in binary and three body collisions, and the mechanisms of many reactions are now understood quite satisfactorily. This information could not have been obtained without a detailed knowledge of the transport phenomena involved. Some of these, such as the...