Growing Electric Space-Charge Waves and Haeff's Electron-Wave Tube

A theory of "growing" electric space-charge waves in drifting, interpenetrating electron streams, or mixed ion and electron streams, has been developed by Pierce, Haeff, and others to explain the operation of the electron-wave tube and other amplifying devices and perhaps also the origin of some solar radio emission.The theory is shown to be untenable, the growth predicted being spurious and due to misinterpretation of the dispersion equations. The waves which are thought to grow are evanescent waves being reflected back into an emitter which is moving through the gas. Only mathematically do they appear as real traveling waves with exponential growth.An alternative mechanism to explain the operation of the amplifying tubes is briefly described.