Development of High-Current Sheet Beam Cathodes for Terahertz Sources

Generation of a sheet beam directly from a scandia-doped dispenser cathode has been investigated and optimized by means of beam-profile simulations and measurements. Rectangular beams 600 mum wide and 100 mum thick with current densities over 50 A/cm
²
have been generated. The beams are stable for at least several hundred hours with the cathodes operating at 950degC
_b
, making them promising candidates for application in the next generation of terahertz vacuum electron devices such as a 0.5-THz superradiant Smith-Purcell radiation source.