Field emission device and reforming treatment method

Patent metadata

Field	Value
Publication number	US-10068741-B2
Application number	US-201515535722-A
Country	US
Kind code	B2
Filing date	Dec 22, 2015
Priority date	Dec 25, 2014
Publication date	Sep 4, 2018
Grant date	Sep 4, 2018

Abstract

In a vacuum chamber ( 1 ), an emitter ( 3 ) and a target ( 7 ) are opposed to each other. A guard electrode ( 5 ) is disposed around an outer circumference of an electron generating portion ( 31 ) of the emitter ( 3 ). A supporting part ( 4 ) supports the emitter ( 3 ) movably in an end-to-end direction of the vacuum chamber ( 1 ). Reforming treatment is performed on the guard electrode ( 5 ) by operating the supporting part ( 4 ), moving the emitter ( 3 ) to an open end ( 21 ) side (non-discharge position) and applying a voltage to repeatedly effect discharge on the guard electrode ( 5 ) in a state where field emission from the electron generation portion ( 31 ) is suppressed. After the reforming treatment, the supporting part ( 4 ) is again operated. The emitter ( 3 ) is moved to an open end ( 22 ) side (discharge position) and placed in a state where field emission from the electron generation portion ( 31 ) is allowed.

First claim

The invention claimed is:

1. A field emission device, comprising:
a vacuum vessel with a cylindrical insulator, the insulator having both ends sealed to define a vacuum chamber on an inner wall side of the insulator;
an emitter located on one end side of the vacuum chamber and having an electron generating portion facing an other end side of the vacuum chamber;
a guard electrode disposed on an outer circumferential side of the electron generating portion of the emitter, the guard electrode having a cylindrical shape extending in an end-to-end direction of the vacuum chamber, one end side of the guard electrode being supported on and fixed to the vacuum vessel;
a target located on the other end side of the vacuum chamber and opposed to the electron generating portion of the emitter; and
a supporting part that has a shape extending from a side of the emitter opposite the electron generating portion and supports the emitter movably in the end-to-end direction of the vacuum chamber, the supporting part being movable such that the emitter is moved in the end-to-end direction and thereby brought into contact with or separated apart from an other end side of the guard electrode by movement of the supporting part such that a distance between the electron generating portion of the emitter and the target is changed.

2. The field emission device according to claim 1 ,
wherein the supporting part includes a bellows that is expandable and contractible in the end-to-end direction of the vacuum chamber and is supported at one end side thereof on the supporting part and at the other end side thereof on the vacuum vessel.

3. The field emission device according to claim 1 ,
wherein the supporting part includes:
a supporting body that has a shape extending from a side of the emitter opposite the electron generating portion and supports the emitter movably in the end-to-end direction of the vacuum chamber;
a magnetic body disposed on an extending direction side of the supporting body;
a circumferential wall that has a shape extending outwardly from a portion of the vacuum vessel opposed to the extending direction side of the supporting body and surrounds a movement range in which the magnetic body moves with movement of the supporting body; and
a magnet disposed on an outer wall surface of the circumferential wall; and

wherein the relationship of t 1 <t<t 2 is satisfied where
t 1 is a distance from the movement range of the magnetic body to the outer wall surface of the circumferential wall at a position opposed to the movement range of the magnetic body in a direction between the magnet and the movement range of the magnetic body;
t 2 is a maximum distance at which a magnetic attractive force is generated between the magnet and the magnetic body by the action of a magnetic force of the magnet on the magnetic body; and
t is a minimum distance between the magnet and the magnetic body.

4. The field emission device according to claim 3 ,
wherein the magnetic body has a diameter larger than that of the extending direction side of the supporting body; and
wherein the circumferential wall includes a narrowed region formed between the movement range of the magnetic body and the emitter and having a diameter smaller than that of the magnetic body.

5. The field emission device according to claim 4 ,
wherein there is a gap left between an inner wall surface of the narrowed region and the movement range of the magnetic body.

6. The field emission device according to claim 1 ,
wherein the guard electrode has a cylindrical shape extending in the end-to-end direction of the vacuum chamber on the outer circumferential side of the emitter; and
wherein the electron generating portion of the emitter is moved by the movement of the supporting part such that the electron generating portion is brought into contact with or separated apart from a target side of the guard electrode.

7. The field emission device according to claim 6 ,
wherein the guard electrode has a small-diameter region formed on the target side thereof.

8. The field emission device according to claim 6 ,
wherein the guard electrode has an edge region formed on the target side thereof such that the edge region extends in a transverse direction of the vacuum chamber and overlaps a circumferential edge region of the electron generating portion of the emitter in the end-to-end direction of the vacuum chamber.

9. The field emission device according to claim 1 , further comprising a grid electrode arranged between the emitter and the target within the vacuum chamber.

10. A reforming treatment method for the field emission device according to claim 1 , comprising:
performing reforming treatment on at least the guard electrode within the vacuum chamber by the application of a voltage to the guard electrode in a state where the electron generating portion of the emitter and the guard electrode are separated apart from each other by operation of the supporting part.

11. A field emission device, comprising:
a vacuum vessel with a cylindrical insulator, the insulator having both ends sealed to define a vacuum chamber on an inner wall side of the insulator;
an emitter located on one end side of the vacuum chamber and having an electron generating portion facing an other end side of the vacuum chamber;
a target located on the other end side of the vacuum chamber and opposed to the electron generating portion of the emitter;
a guard electrode disposed on an outer circumferential side of the electron generating portion of the emitter, the guard electrode having a cylindrical shape extending in an end-to-end direction of the vacuum chamber, one end side of the guard electrode being supported on and fixed to the vacuum vessel;
a supporting body that has a shape extending from a side of the emitter opposite the electron generating portion and supports the emitter, the supporting body being movable such that the emitter is moved in the end-to-end direction and thereby brought into contact with or separated apart from an other end side of the guard electrode by movement of the supporting body; and
a bellows supported at one end side thereof on the supporting body and supported at the other end side thereof on the vacuum vessel thereby comprising a part of the vacuum vessel.

12. The field emission device according to claim 11 ,
wherein the guard electrode has a cylindrical shape extending in the end-to-end direction of the vacuum chamber on the outer circumferential side of the emitter; and
wherein the electron generating portion of the emitter is moved by the movement of the supporting body such that the electron generating portion is brought into contact with or separated apart from a target side of the guard electrode.

13. The field emission device according to claim 12 ,
wherein the guard electrode has a small-diameter region formed on the target side thereof.

14. The field emission device according to claim 12 ,
wherein the guard electrode has an edge region formed on the target side thereof such that the edge region extends in a transverse direction of the vacuum chamber and overlaps a circumferential edge region of the electron generating portion of the emitter in the end-to-end direction of the vacuum chamber.

15. The field emission device according to claim 11 , further comprising a grid electrode arranged between the emitter and the target within the vacuum chamber.

16. A reforming treatment method for the field emission device according to claim 11 , comprising:
performing reforming treatment on at least the guard electrode wit

Assignees

• Meidensha Electric Mfg Co Ltd

Inventors

• Takahashi Daizo
• Fukai Toshimasa
• Tanimizu Toru

Classifications

• H01J35/065 Primary

  Field emission, photo emission or secondary emission cathodes · CPC title

• H01J2235/205

  Gettering · CPC title

• H01J1/304 Primary

  Field-emissive cathodes · CPC title

• H01J35/16

  Vessels; Containers; Shields associated therewith · CPC title

• H01J35/12

  Cooling non-rotary anodes · CPC title