Re-entrant crossed-field amplifiers with enhanced performance

To identify in detail the factors that limit the average power capability of the cold-cathode r-f triggered crossed-field amplifier, a research tube has been built and tested. The research tube features segmented collector and delay line to measure current and velocity distribution along the beam. An independent cheek on beam distribution is provided by a row of x-ray dimples--thin metal and beryllium-covered pinholes in the side wall for x-radiation indication of bombardment on the line or collector. A slide will be shown of the images so obtained in the region of the output where some kind of undesired and quite complex discharge is seen to occur. The tube is also provided with three optical windows and four r-f probes, in addition to the normal input and output. The optical windows show the expected cathode fluorescence, and the window nearest the output also shows a glow in the delay line that probably has the same cause as the x-ray pattern.