An electron tube in which current amplification is achieved by means of secondary emission of electrons. Primary electrons are released from the cathode by some means, such as the photoelectric effect. These are accelerated by a high potential applied to the first anode. The anodes, termed dynodes, are made from a good secondary emitter and on impact a greater number of electrons is produced. These are then accelerated in turn by the second and subsequent anodes, to each of which an increasing positive potential is applied (see diagram). A large output pulse is produced at the final anode – the collector – which is operated at a very high potential. See also photomultiplier.

Electron multiplier