Electron emission device comprising carbon nanotubes yarn and method for generating emission current

An electron emission device, comprising:

• an electron emitter comprising a plurality of one-dimensional nanostructures;
• an anode opposite to and spaced apart from the electron emitter;
• a first power supply circuit configured for electrically connecting the electron emitter and the anode with a power supply to generate an electric field between the electron emitter and the anode;
• and
• a second power supply circuit configured for electrically connecting the electron emitter with a power supply to supply a heating current for heating the electron emitter whereby electrons emit therefrom;
• wherein the electron emitter further comprises a sleeve defining an opening therein and a filament placed in the opening, and the one-dimensional nanostructures are formed on an outside surface of the sleeve and electrically connected therewith, the first power supply circuit is electrically connected with the anode and the sleeve, and the second power supply circuit is electrically connected with two terminals of the filament.