Frequency conversion in a photomultiplier tube during the interaction of the photoelectron flux with the heterodyne field

An analysis is made of the conversion of the modulation frequency of optical radiation in a photomultiplier tube during the interaction of the photoelectron flux with the heterodyne field in a wide range of flight angles and for an arbitrary heterodyne signal. Computer calculations of the dependence of the difference-frequency current component on the system parameters are presented. It is shown that, in general, a receiving system based on a photomultiplier tube with an additional grid is characterized by two processes: current cutoff and density bunching of the photoelectron flux. The current cutoff predominates at small angles of flight.