The ten invited papers presented at the Symposium on The Role of Ion
Composition in Understanding Magnetospheric Processes, which was held on
11 August 1981 in Edinburgh, Scotland, have formed the principal basis
for this book. The symposium was a part of the Fourth Scientific
Assembly of the International Association of Geomagnetism and Aeronomy
and was convened by the Division III Working Group on Composition of Hot
Magnetospheric Plasma under the co- chairmanship of Dr. Gerhard
Haerendel and myself. The symposium papers have been expanded and are
supplemented in this book by several additional papers to provide a more
comprehensive topical review and a current status report on experimental
and theoretical research that relate to our present understanding of the
energetic ion composition in Earth's magnetosphere. Thus, the papers
include new results as well as a review of published results, with
rather extensive reference lists, in the hope that this collection will
be useful both for information on current research activities as well as
a somewhat lasting topical resource for the space science community.