Development of a transmission-mode diamond secondary electron source

Vacuum electron devices such as traveling wave tubes designed to operate at frequencies near 300 GHz will require electron beam and circuit dimensions of several hundred microns and several micron precision, likely fabricated using techniques such as DRIE or LIGA. To increase power while maintaining the required dimensions such devices will require either multiple round beams, "sheet" beams, or similar. These requirements may be most easily met with a cold electron source capable of emitting high current density, and which may be lithographically patterned and positively aligned with the interaction structure. To date, achieving high current as well as high current density from field emitter arrays has been difficult, and achieving stable and uniform emission has often required current limiting structures in series with each emission site, degrading beam quality.