Disclosed is an X-ray source, including: a cathode; an anode positioned on the cathode so as to face the cathode; emitters formed on the cathode; a gate electrode positioned between the cathode and the anode and including openings at positions corresponding to those of the emitters; an insulating spacer formed between the gate and the anode; and a coating layer formed on an internal wall of the insulating spacer, and including a material having a lower secondary electron emission coefficient than that of the insulating spacer.
1. An X-ray source, comprising:
a cathode;
an anode positioned to face the cathode;
emitters formed on the cathode;
a gate electrode positioned between the cathode and the anode and including openings at positions corresponding to those of the emitters;
an insulating spacer formed between the gate and the anode; and
a coating layer formed on an internal wall of the insulating spacer, and including a material having a lower secondary electron emission coefficient than that of the insulating spacer,
wherein the coating layer is only present on portions of the internal wall that are closer to the cathode, and exposed portions of the internal wall that are closer to the anode are free from the coating layer.
2. The X-ray source of claim 1 , wherein the coating layer prevents the insulating spacer and the electrons from colliding with each other and secondary electrons from being generated.
3. The X-ray source of claim 1 , wherein the coating layer includes a chromic oxide (Cr 2 O 3 ) or a titanium oxide (TiO 2 ).
4. The X-ray source of claim 1 , wherein the insulating spacer has a tube form.
5. The X-ray source of claim 1 , wherein a thickness of the coating layer decreases as the coating layer approaches the anode.
6. The X-ray source of claim 1 , wherein the coating layer includes:
a first layer; and
a second layer having a different secondary electron emission coefficient from that of the first layer.
7. The X-ray source of claim 1 , wherein the coating layer includes:
a first layer formed on an internal wall of the insulating spacer which is exposed between the gate electrode and the anode; and
a second layer formed on the first layer and having a different secondary electron emission coefficient from that of the first layer.
8. The X-ray source of claim 1 , wherein the gate electrode has a form bent toward the anode in a surrounding region of the opening.
9. The X-ray source of claim 1 , wherein the emitter is a carbon nano tube emitter.
10. The X-ray source of claim 1 , wherein the gate electrode has a mesh form.
11. The X-ray source of claim 1 , wherein an exposed surface of the anode is inclined at a non-normal angle with respect to an axis of the cylinder.