In the past three decades, the development of nuclear physics facilities for
fundamental and applied science purposes has required an increasing current of
multicharged ion beams. Multiple ionization implies the formation of dense and
energetic plasmas, which, in turn, requires specific plasma trapping
configurations. Two types of ion source have been able to produce very high
charge states in a reliable and reproducible way: electron beam ion sources
(EBIS) and electron cyclotron resonance ion sources (ECRIS). Multiple
ionization is also obtained in laser-generated plasmas (laser ion sources
(LIS)), where the high-energy electrons and the extremely high electron density
allow step-by-step ionization, but the reproducibility is poor. This chapter
discusses the atomic physics background at the basis of the production of
highly charged ions and describes the scientific and technological features of
the most advanced ion sources. Particular attention is paid to ECRIS and the
latest developments, since they now represent the most effective and reliable
machines for modern accelerators.Comment: 42 pages, contribution to the CAS-CERN Accelerator School: Ion
Sources, Senec, Slovakia, 29 May - 8 June 2012, edited by R. Baile