Spectroscopy of multi-charged ions

Recent and future applications of multiply charged ions to spectroscopy and atomic structure are discussed. The experimental techniques use either very fast ions produced in heavy ion accelerators, or slow ions produced directly both in electron beam ion sources and from collisions of fast accelerated ions. For the accelerated fast ions, spectroscopic measurements using gas target excitation, solid foil excitation and laser excitation are compared. In gas target excitation, both X-ray and electron spectroscopy have been applied to analyse atomic structures and secondary collision effects. Highly-charged secondary ions have also been trapped electro-magnetically for further similar studies in controlled conditions. Spectroscopic detection following solid foil interaction has led to atomic lifetime measurements, principally of metastable level, analysis of complex highly-ionized heavy ion spectra, and investigations of relativistic and QED effects in few electron ions. (Auth.)