Improved Field Emitter Array Cathodes for Advanced RF Sources

Field Emission Array (FEA) cathodes possess remarkable properties that would be extremely beneficial for vacuum electron devices, including high current emission density, operation at room temperature, gated electrode operation, and low cost-high quantityproduction. Unfortunately, these devices are subject to catastrophic failure during electrical arcs, which are common during device processing. They are also subject to damage from ion bombardment and often operate with nonuniform emission. This programwould develop techniques enabling these cathodes to survive high energy arcs and ion bombardment. Techniques will also be developed to provide uniform emission over the cathode surface. Calabazas Creek Research, Inc. possesses an experimental device fortesting FEA cathodes at voltages exceeding 100 kV in a vacuum electron device structure similar to a high power RF device. An array of computational tools are available for detailed modeling of the mechanical and electrical performance. The Phase I programwill quantify the requirements for device survival in typical RF devices and develop structures and techniques to achieve reliable, long-life, high quality performance. Successful development of FEA cathodes capable of long life, reliable operation in RFdevices will dramatically improve the performance while decreasing the design, manufacturing, and operating costs. It will facilitate new devices operating at significantly lower voltages with greater bandwidth and efficiency. It will also eliminaterequirements for cathode heater power.