  The history of the magnetron and Penning electrode geometry is briefly
outlined. Plasma generation by electrical discharge-driven electron impact
ionization is described and the basic physics of plasma and electrodes relevant
to magnetron and Penning discharges are explained. Negative ions and their
applications are introduced, along with their production mechanisms. Caesium
and surface production of negative ions are detailed. Technical details of how
to build magnetron and Penning surface plasma sources are given, along with
examples of specific sources from around the world. Failure modes are listed
and lifetimes compared.
