Miniature reservoir cathode—an update

We report on recent work to produce a small, low power, low cost reservoir cathode capable of long life (more than 100,000 h) at high loading (>5 A/cm2). Our objective is a highly manufacturable, commercial device costing less than US$ 30. Small highly loaded cathodes are needed, especially for millimeter traveling wave tubes, where focusing becomes difficult when area convergence ratios are too high. We currently have three models ranging from 0.060 to 0.125 in. diameter.