P1–35: Improvements in miniature wire-strung cathodes for high frequency VEDs

This paper reports on design and process improvements for wire-suspended cathodes, which were first presented one year ago. These improvements provide lower power, further reduction in size, better stability and accuracy, and higher loading. Current assemblies dissipate less than 150 milliwatts at cathode diameter of .33 mm. The cathodes are too small for use with conventional heaters and so are heated from behind by an electron beam or an intense light beam. Laser light transmitted via optical fiber to the back of the cathode was employed. The cathodes are now electrically isolated from the focus electrode, thus allowing beam cutoff and modulation. We discuss advantages over current art and present data on emission, temperature, power and mechanical stability.