ABSTRACT
However, for beam transport, not only the extracted current, but also the beam quality is important. Beam transport can be affected if the space charge compensation is not constant in time or if the beam intensity changes with time. The current distribution in charged particle beams depends on the properties of the emitting medium and the beam-forming system, the extraction system. If the emitting area is too small to deliver enough current, it cannot be increased above a certain limit without reduction in beam quality. There are two different kinds of compensation effects: space charge compensation and current compensation. The emittance of the beam is determined by the emitting area, its shape, and the temperature of the emitted particles. In plasma sources the ions are generated in a discharge chamber. The emittance of the extracted beam is given by the plasma parameter, existing magnetic fields, and aberrations in the extraction.
