HIGH-CURRENT DC MICROWAVE ION SOURCES (INVITED)

Microwave-driven ion sources and, in particular, electron cyclotron resonance (ECR) ion sources have customarily been used almost exclusively for the production of multiply charged ions. However, very reliable microwave sources that generate high-current low-emittance beams of singly charged ions have recently been developed for ion implanters and accelerator injectors. In this paper the elementary concepts of high-current microwave ion sources are summarized. The distinction between the ECR and the off-resonance coupling of the microwave power into the plasma is addressed as well as the difficulty of extracting high-quality ion beams in the presence of the large magnetic fields associated with microwave ion sources. The features of a selection of high-current microwave ion sources are reviewed.