multiplier is analogous to the photomultiplier transducer for ultraviolet/visible
radiation with each dynode being held at a successively higher voltage.
The cathode and several dynodes have Cu/Be surfaces from which bursts
of electrons are emitted when struck by energetic ions or electrons. Electron
multipliers with up to 20 dynodes are available that provide a current
gain of 10 million.
In general, electron multipliers are rugged and reliable and capable of providing high-current gains in nanosecond response times. These transducers are placed directly behind the exit slit of a magnetic sector mass analyzer. Ions reaching the transducer have enough kinetic energy to eject electrons from the first stage. Electron multipliers can also be used with quadrupole mass analyzers but the ion beam is accelerated to several thousand electron volts prior to striking the first stage.