Carbon nanotube cathodes as electron sources for microwave amplifiers

Cold cathodes based on carbon nanotubes allow to produce a modulated electron beam. Using an array of vertically aligned CNs that exhibit an aspect ratio of about 200, we demonstrated the modulation of a high current density beam (~ 1 A/cm2 at 1.5 and 32 GHz frequencies. Such CN cathodes are very promising for their use in a new generation of compact, highly efficient and low cost amplifiers that operate between 10 and 100GHz.