Very stable large current density printed carbon nanotube field-emission cathode applied in electron gun

We have fabricated large current density cold cathodes based on the printed carbon nanotubes(CNTs), which are applied in the compact vacuum electron devices including X-ray sources and microwave tubes. The peak value of the cathode current in the diode structure driven by DC voltage is up to 19.88mA (current density: ∼2.51A/cm 2 ), along with the fluctuations of the current smaller than 5.3% during the period of about 27 hours. The experimental results show that printed CNTs have the potential as field emission electron sources.