  This chapter describes the basic principles, design features and
characteristics of microwave discharge ion sources. A suitable source for the
production of intense beams for high-power accelerators must satisfy the
requirements of high brightness, stability and reliability. The 2.45 GHz
off-resonance microwave discharge sources are ideal devices to generate the
required beams, as they produce multimilliampere beams of protons, deuterons
and singly charged ions. A description of different technical designs will be
given, analysing their performance, with particular attention being paid to the
quality of the beam, especially in terms of its emittance.
