A novel rectangular-ring slow-wave structure for interaction with a sheet electron beam

摘要

Conventional round electron beams have a practical current limit beyond which space-charge forces will de-bunch the beam and prevent further rf power amplification. Alternatively, rectangular cross-section sheet electron beams can circumvent this limitation by distributing the current over a larger area by stretching the width of the beam. This topology can enable a >5× increase in current over round beam systems while maintaining relatively low operating voltages. Another advantage of the sheet beam is that the coupling impedance has a relatively small dependence on beam thickness.