Preparation of Miniature Thermionic Cathode to be Used in THz Devices

A kind of miniature thermionic cathode is prepared by depositing an anti-emission Ta-Zr composite coating on impregnated scandate cathode surface via dual Ion-Beam-Assisted Deposition (Dual IBAD) and then etching in the center of the anti-emission coating a mini electron emission zone with a diameter of
$\mathbf{100}\boldsymbol{\mu} \mathbf{m}$
via Focus Ion Beam(FIB). Experimental results show that dense coating prepared by Dual IBAD is more effective than loose coating prepared by magnetron sputtering in suppressing electron emission, that Ta/Zr coating is more effective than Zr coating in suppressing electron emission, and that the average current density of the cathode can reach 43A/cm
²
at 950 °C.