Field emission X-ray source device

A field emission X-ray source device, comprising:

• an insulating housing having a tube shape and extending in a longitudinal direction between a first side and a second side;
• an anode electrode covering the first side of the insulating housing;
• a gate electrode including a first gate covering the second side of the insulating housing and a second gate in a cylindrical shape disposed on the first gate, inside the insulating housing;
• a cathode electrode disposed inside the insulating housing;
• an electronic emitter provided on the cathode electrode, and configured to emit an electron beam toward the anode electrode;
• a target provided on the anode electrode and facing the electronic emitter, and configured to enable X-rays to be generated by collision with the electron beam, and
• a cylindrical insulating spacer rested on the first gate, inside the second gate,
• wherein the cathode electrode is positioned above the insulating spacer inside the second gate in the longitudinal direction and between the anode electrode and the second gate.