ABSTRACT
Microwave ion sources were first developed for multiply charged ion production at the end of the 1960s by R. Geller and his group using electron cyclotron resonance heating of the electrons and magnetic confinement for the ions. The wavelength of microwaves is, in contrast to radio frequency ion sources, of similar dimension or smaller than the ion source. In most microwave ion sources, a magnetic field is superimposed to improve the microwave heating of the plasma electrons. A microwave ion source consists of a single or multimode cavity, which is also the discharge chamber, or contains a separate vessel made of insulating material. If the magnetic field exceeds the electron cyclotron resonance value and the neutral particle density is sufficiently high, the energy of the microwave is effectively absorbed by off-resonance heating processes. Microwave ion sources run well with oxygen and corrosive gases.
