Thermionic electron emission device

A thermionic electron emission device comprising:

• an insulating substrate;
• one or more lattices located on the insulating substrate, wherein each of the one or more lattices comprises:
• a first, a second, a third and a fourth electrode down-leads located on the insulating substrate to define an area, wherein the first and the second electrode down-leads are parallel to each other, the third and the fourth electrode down-leads are parallel to each other, and the first and the second electrode down-leads are insulated from the third and the fourth electrode down-leads respectively;
• and
• a thermionic electron emission unit located in the area, wherein the thermionic electron emission unit comprises a first electrode, a second electrode, and a thermionic electron emitter, the first electrode and the second electrode are located and spaced from each other;
• the first electrode is electrically connected to the first electrode down-lead and the second electrode is electrically connected to the third electrode down-lead;
• wherein the thermionic electron emitter comprises a continuous carbon nanotube film structure having a first end electrically connected to the first electrode and a second end electrically connected to the second electrode, the carbon nanotube film structure comprises a carbon nanotube film, the carbon nanotube film comprises a plurality of carbon nanotubes joined end to end along axial directions of the carbon nanotubes by contacting with each other directly, and the first electrode and the second electrode are directly and electrically connected with each other by the plurality of carbon nanotubes.