ECR ION SOURCES - PRESENT STATUS AND PROSPECTS

Although now widely used for many applications, the electron cyclotron resonance ion sources (ECRIS), an outgrowth of the fusion plasma rese arch, still suffer from some mystification, or at least from a lack of understanding. This article is an attempt to give a broad overview of the today ECRIS activity devoted to the production of highly charged ions: it therefore describes both physics and theory efforts, technolo gy, performances, plans and prospects as well. An important chapter gi ves the status of understanding the ECRIS behavior, both the current t hinking on how they operate and the experimental evidences whenever it is possible. The various existing sources, their design and main feat ures, are then surveyed. At last the present trends of development, th e potential directions for future improvement are examined.