X-Ray Source with Tube-Shaped Field-Emitter

Patent metadata

Field	Value
Publication number	US-2017200580-A1
Application number	US-201615342575-A
Country	US
Kind code	A1
Filing date	Nov 3, 2016
Priority date	Jan 7, 2016
Publication date	Jul 13, 2017
Grant date	—

Abstract

An x-ray tube can include an electron-emitter, which can include a tube-shape with a minimum inside diameter of at least 0.5 millimeters. The electron-emitter can provide field-emission of electrons, and thus can avoid the electrical power required for heating, and can avoid degradation due to high temperature of, a thermionic-emission electron-emitter. This type of electron-emitter, with a tube-shape, can have a relatively large electron-emission region, allowing high electrical current without excessive current density.

First claim

What is claimed is:

1 . An x-ray tube comprising an electron-emitter, an anode, an x-ray window, and an evacuated-region between the electron-emitter and the anode, wherein:
a. the electron-emitter is electrically insulated from the anode; b. the anode includes a material for generation of x-rays in response to impinging electrons from the electron-emitter; and c. the electron-emitter:
i. is capable of field-emission of electrons;
ii. includes a tube-shape with a minimum inside diameter of at least 0.5 millimeters;
iii. has an open-end facing the anode, with at least a portion of the evacuated-region located between the open-end and the anode;
iv. includes an electron-emission region, capable of emitting electrons to the anode, at an inside of the electron-emitter, or at the open-end of the electron-emitter, or both; and
v. includes an electrically-conductive path from the electron-emission region to an electrical connection for a power-supply.

2 . The x-ray tube of claim 1 , wherein the open-end is substantially perpendicular to a longitudinal-axis of the electron-emitter.

3 . The x-ray tube of claim 1 , wherein a cross-section of the open-end of the electron-emitter is pointed and the open-end has a pointed-edge.

4 . The x-ray tube of claim 3 , wherein an internal angle of the pointed-edge of the open-end of the electron-emitter is less than 30 degrees relative to a longitudinal-axis of the electron-emitter.

5 . The x-ray tube of claim 3 , wherein the pointed-edge has an exterior bevel.

6 . The x-ray tube of claim 5 , wherein the exterior bevel of the pointed edge is linear.

7 . The x-ray tube of claim 1 , wherein a distance between the open-end of the electron-emitter and the anode is greater than 0.1 millimeters and less than 2 millimeters.

8 . The x-ray tube of claim 1 , further comprising an enclosure, wherein:
a. the enclosure is hermetically-sealed to the anode; b. the enclosure at least partially encloses the evacuated-region; c. the enclosure circumscribes at least a portion of the electron-emitter; d. the enclosure is electrically conductive; e. the electron-emitter has a proximal-end opposite of the open-end; f. an inner-surface of the enclosure tapers inward, with a smaller inside-diameter closer to the open-end of the electron-emitter, and a larger inside-diameter closer to the proximal-end of the electron-emitter, forming a taper-angle, in order to increase an electric-field gradient at the open-end of the electron-emitter; and g. the taper-angle is between 2 degrees and 20 degrees.

9 . The x-ray tube of claim 1 , wherein:
a. the anode includes the x-ray window; b. the x-ray window has a transmissivity of greater than 50% for x-rays having an energy of 1.74 key; c. the x-ray window has a concave-side facing the electron-emitter; and d. the concave-side of the x-ray window includes the material for generation of x-rays.

10 . The x-ray tube of claim 9 , wherein the x-ray window includes a substantially-flat-side that is outside of the x-ray tube and opposite of the concave-side.

11 . The x-ray tube of claim 1 , wherein a pressure of the evacuated-region is less than 5×10 −9 Torr.

12 . The x-ray tube of claim 1 , wherein the electron-emission region includes carbon.

13 . The x-ray tube of claim 1 , wherein the electron-emission region includes a doped material.

14 . The x-ray tube of claim 1 , wherein the electron-emission region has a surface area of at least 15 square millimeters.

15 . The x-ray tube of claim 1 , wherein the x-ray tube forms part of an x-ray source, the x-ray source comprising the x-ray tube electrically connected to a power supply, and the power supply is capable of causing a voltage between the electron-emitter and the anode of at least 1 kilovolt.

16 . The x-ray tube of claim 1 , wherein:
a. the anode includes a cone-shape; b. a pointed-end of the cone-shape points towards an open-end of the electron-emitter; c. an outer-face of the cone-shape includes the material for generation of x-rays; and d. the x-ray window has a curved shape and at least partially encircles the pointed-end of the cone-shape and the open-end of the electron-emitter.

17 . The x-ray tube of claim 16 , wherein:
a. the x-ray window is annular-shaped and encircles the pointed-end of the cone-shape; and b. the x-ray tube is capable of outward emission of x-rays in a 360 degree arc around a circumference of the pointed-end of the cone-shape and between 0.25*pi and 1.75*pi steradians.

18 . A method of using the x-ray tube of claim 1 , the method comprising:
a. emitting x-rays from the x-ray tube into a region-of-air near a device with an electrostatic charge; b. forming ions in the region-of-air; and c. using the ions to dissipate the electrostatic charge from the device.

19 . An x-ray tube comprising an electron-emitter, an anode, an x-ray window, and an evacuated-region between the electron-emitter and the anode, wherein:
a. the electron-emitter is electrically insulated from the anode; b. the anode includes a material for generation of x-rays in response to impinging electrons from the electron-emitter; and c. the electron-emitter:
i. is capable of field-emission of electrons;
ii. includes a tube-shape;
iii. has an open-end facing the anode, with at least a portion of the evacuated-region located between the open-end and the anode, a cross-section of the open-end of the electron-emitter is pointed, and the open-end has a pointed-edge with an exterior bevel;
iv. includes an electron-emission region, capable of emitting electrons to the anode, at an inside of the electron-emitter, or at the open-end of the electron-emitter, or both; and
v. includes an electrically-conductive path from the electron-emission region to an electrical connection for a power-supply.

20 . An x-ray tube comprising an electron-emitter, an anode, an x-ray window, and an evacuated-region between the electron-emitter and the anode, wherein:
a. the electron-emitter is electrically insulated from the anode; b. the anode includes a material for generation of x-rays in response to impinging electrons from the electron-emitter; and c. the electron-emitter:
i. is capable of field-emission of electrons;
ii. includes a tube-shape;
iii. has an open-end facing the anode, with at least a portion of the evacuated-region located between the open-end and the anode, a cross-section of the open-end of the electron-emitter is pointed and an internal angle of the pointed-edge of the open-end of the electron-emitter being less than 30 degrees relative to a longitudinal-axis of the electron-emitter;
iv. includes an electron-emission region, capable of emitting electrons to the anode, at an inside of the electron-emitter, or at the open-end of the electron-emitter, or both; and
v. includes an electrically-conductive path from the electron-emission region to an electrical connection for a power-supply.

Assignees

• Moxtek Inc

Inventors

• Miller Eric
• Hansen Bill

Classifications

• A61B6/40

  Arrangements for generating radiation specially adapted for radiation diagnosis · CPC title

• H01J35/186

  used as targets or X-ray converters · CPC title

• H01J35/065 Primary

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

• H01J35/32

  Tubes wherein the X-rays are produced at or near the end of the tube or a part thereof which tube or part has a small cross-section to facilitate introduction into a small hole or cavity · CPC title

• H01J35/08

  Anodes; Anti cathodes · CPC title