- In certain electron tubes, especially photomultiplier tubes, one of multiple electrodes which produce secondary emissions of electrons. Each successive electron mirror, or dynode, in the series produces greater and greater amounts of electrons. Depending on the total number of dynodes, the electron pulse may be millions of times larger than it was at the beginning of the tube. Used, for instance, for detection and measurement of minute flashes of light, and in TV camera tubes. Also called dynode.