Electron beam generation using a ferroelectric cathode

Data is presented on the production of electron beams from a ferroelectric cathode at voltages of order 0.5 MV and current densities of order 100 A/cm². In comparison with data at lower voltages, the beam current scales as the three-halves-power of the voltage. An interpretation of the voltage dependent scaling, based on the coupling of electrostatic energy from the ferroelectric to the gun, is presented     

High-power microwave generation using a ferroelectric cathodeelectron gun

A two-stage 500 kV 200-A ferroelectric electron gun has been designed, fabricated, tested, and used in a high power microwave amplifier experiment. We report on the operational characteristics of the gun including measurements of the beam dynamics. The optimum conditions for application of the trigger and its timing are also reported. Faraday cup measurement shows that the beam radius is 4.1 mm, in good agreement with simulation. The gun is designed for use in traveling-wave tube amplifiers, and testing of an X-band amplifier driven by the gun is reported. A peak output power of 5.9 MW has been observed from a single stage amplifier driven by a 100 A. 450 kV beam. This corresponds to energy converging efficiency of 13.1% and is the first observation of high power (~MW) microwave generation using the beam generated from a ferroelectric cathode,     

Low group velocity traveling wave tube amplifiers

We report experimental and theoretical results from research into high power X-band traveling wave tube amplifiers designed to eliminate sidebands caused by reflections from the output of such structures. These amplifiers have a low energy velocity, such that the time it takes a wave to be reflected from the output to the input is of the order of, or greater than, the electron beam pulse duration. The elimination of sidebands and the effects of reflections is achieved by this transit time isolation, The bandwidth of the output spectrum is limited by the low pass-band of the periodic structures. Such amplifiers have been operated at power levels of up to 160 MW at 9 GHz for 50 ns pulse durations