An electron multiplier is the most common detector. An ion from the analyzer strikes the first dynode, knocking loose a few secondary electrons. Those are accelerated to the next dynode, where each knocks loose more — cascading down a chain until a single ion has become a pulse of millions of electrons, large enough to measure.

How it works

Send an ion and watch the electron count double at every dynode down the zigzag chain.

electrons hit every dynode in order → number doubles each step
ion from analyzer secondary electron stepped voltages force each electron to the next dynode

The electrons must hit every dynode in sequence — the dynodes are held at stepped voltages, so the field always pulls electrons to the next one in line. Multiplication happens at every step, which is how the detector can register even a single ion.

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