How a Photomultiplier Tube Works
the electrons emitted from the cathode are accelerated towards the first dynode that is maintained 90-100V positive with respect to the cathode. Each photoelectron that strikes the dynode surface produces several electrons, called secondary electrons, that are accelerated to dynode 2. By the time this process has been repeated at each dynode, 10^5 to 10^7 electrons have been produced. All electrons are finally connected at the anode to proved an average current.