Electron emitting construct configured with ion bombardment resistant
A robust cold cathode uses an electron emitting construct design possibly for an x-ray emitter device. The electron beam emitted by the emitting construct is focused and accelerated by an electrical field towards an electron anode target. A shield is provided to prevent a cold cathode from being damaged by ion bombardment in high-voltage applications and a non-emitter zone may provide a robust ion bombardment zone. The system is further configured to provide an angled target anode or a stepped target anode to further reduce the ion bombardment damage.
1. An x-ray emitting device comprising:
an electron anode target; and
a cold cathode electron source having
at least one electron emitting zone configured to emit electrons towards said electron anode target, and
at least one non-emitting ion bombardment zone,
wherein said at least one electron emitting zone further comprises
an electrically insulating substrate,
an array of nano-Spindt field emission type electron sources,
a plurality of control contacts configured for controlling said electron sources,
a focus electrode configured for applying a voltage above said array, and
a shield disposed over said control contacts, said shield constituting part of the focus electrode, and
wherein said at least one non-emitting ion bombardment zone is disposed along a line perpendicular to the surface of said electron anode target; said at least one ion bombardment zone being distinct from said electron emitting zone of said cold cathode electron source.
2. The x-ray emitter device of claim 1 , further comprising a focus structure configured to direct electron towards said electron anode target such that said electrons strike an electron focal spot at an angle.
3. The x-ray emitter device of claim 2 , wherein said at least one ion bombardment zone is disposed along a line perpendicular to the surface of said electron anode target at said electron focal spot.
4. The x-ray emitter device of claim 2 , wherein said at least one ion bombardment zone has larger dimensions than said electron focal spot.
5. The x-ray emitter device of claim 2 , wherein said at least one ion bombardment zone is coated with an elemental material.
6. The x-ray emitter device of claim 5 , wherein said elemental material comprises a pure metal.
7. The x-ray emitter device of claim 5 , wherein said elemental material comprises carbon.
8. The x-ray emitter device of claim 2 , wherein said at least one ion bombardment zone comprises a central region surrounded by said electron emitting zone of said cold cathode electron source.
9. The x-ray emitter device of claim 2 , wherein the electrically insulating substrate is silicon-based.