Reduced power consumption X-ray source

• US 8,804,910 B1
• Filed: 11/30/2011
• Issued: 08/12/2014
• Est. Priority Date: 01/24/2011
• Status: Expired due to Fees

• Current Assignee: Moxtek Inc (Nippon Kayaku Company Limited)
• Original Assignee: Moxtek Inc (Nippon Kayaku Company Limited)
• Inventors: Wang, Dongbing, Reynolds, Dave
• Primary Examiner(s): Kiknadze, Irakli
• Application Number:
  US13/307,579
• Time in Patent Office: 986 Days
• Field of Search: 378/101, 378/119, 378/121, 378136-138
• US Class Current: 378/101
• CPC Class Codes: H01J 2235/167 against thermal (heat) energy
• CPC Class Codes: H01J 35/16 Vessels; Containers; Shields associated therewith
• CPC Class Codes: H05G 1/10 Power supply arrangements for feeding the X-ray tube supply circuits with converters in general H02M; supply circuits for emitters and amplifiers H04B1/16 - H04B1/1623

Abstract

A reduced power consumption x-ray source comprising:

• • In one embodiment, an x-ray tube including an infrared heat reflector disposed inside an x-ray tube cylinder between the cathode and the anode and oriented to reflect a substantial portion of infrared heat radiating from a filament back to the filament, thus reducing heat loss from the filament.
  • In another embodiment, an alternating current source for an x-ray tube filament including a switch for allowing power to flow to the filament for a longer or shorter time depending on the desired output x-ray flux.
  • In another embodiment, a neutral grounded, direct current (DC) high voltage, power supply with parallel high voltage multipliers, each supplied by separate alternating current sources, but both the output of one alternating current source connected to ground and the input of another alternating current source connected to ground. The output of both high voltage multipliers are connected.

Claims

1. An x-ray tube comprising:

a) an evacuated insulative cylinder;

b) an anode disposed at one end of the insulative cylinder including a material configured to produce x-rays in response to impact of electrons;

c) a cathode disposed at an opposing end of the insulative cylinder from the anode, the cathode including a filament disposed at an inward face of the cathode, the filament configured to produce electrons accelerated towards the anode in response to an electric field between the anode and the cathode;

d) an infrared heat reflector disposed inside the insulative cylinder between the cathode and the anode, and oriented to reflect a substantial portion of infrared heat radiating from the filament back to the filament;

e) the reflector having a curved, concave shape facing the cathode;

f) an opening in the reflector aligned with an electron path between the filament and the anode; and

g) the opening sized to allow a substantial amount of electrons to flow from the filament to the anode.

2. The device of claim 1, wherein the curved, concave shape includes a portion of a spherical shape.

3. The device of claim 1, wherein an area of the opening is at least 10% of a surface area of the reflector on a side of the reflector facing the filament.

4. The device of claim 1, wherein an area of the opening is at least 25% of a surface area of the reflector on a side of the reflector facing the filament.

5. The device of claim 1, wherein the reflector has a metallic surface on a side facing the filament.

6. The device of claim 1, wherein the reflector has a reflectivity on a side facing the filament of greater than about 0.75 for infrared wavelengths of 1 to 3 μ

m.

7. The device of claim 1, wherein the filament is disposed at a focal point of the reflector.

8. An alternating current source for an x-ray tube filament comprising:

a) a voltage source;

b) a switch that is electrically coupled to the voltage source;

c) the switch having a first switch position and a second switch position;

d) electrical current flow through the switch when the switch is in the first switch position is at least 3 times more than the electrical current flow through the switch when the switch is in the second switch position;

d) a direct current to alternating current (DC to AC) converter;

i) configured to provide alternating current to the x-ray tube filament;

ii) electrically coupled to the voltage source through the switch; and

iii) provides more alternating current to the x-ray tube filament when the switch is in the first position;

f) the x-ray tube filament configured to produce an electron beam having an electron beam current level;

g) a feedback module receiving input regarding the electron beam current level; and

h) the feedback module directing the switch to the first switch position for more or less time based on the electron beam current level.

9. The alternating current source of claim 8 wherein:

a) the feedback module is configured to set the switch to the first switch position for more time when the electron beam current level is below a first set point; and

b) the feedback module is configured to set the switch to the first switch position for less time when the electron beam current level is above a second set point.

10. The alternating current source of claim 8 wherein the DC to AC converter provides alternating current to the x-ray tube filament through a transformer.

11. The alternating current source of claim 8 wherein the DC to AC converter is configured to provide the alternating current to the x-ray tube filament at a frequency between about 0.5 MHz to about 200 MHz.

12. The alternating current source of claim 8 wherein the switch is an analog switch.

13. The alternating current source of claim 8 wherein electrical current flow through the switch when the switch is in the first switch position is at least 100 times more than the electrical current flow through the switch when the switch is in the second switch position.

14. The alternating current source of claim 8 wherein no electrical current is allowed to flow through the switch when the switch is in the second switch position.

15. A neutral grounded, direct current (DC) high voltage, power supply comprising:

a) a first alternating current (AC) source having a first connection and a second connection;

b) a second AC source having a first connection and a second connection;

c) a first high voltage multiplier having;

i) an AC connection;

ii) a ground connection;

iii) an output connection;

d) a second high voltage multiplier having;

i) an AC connection;

ii) a ground connection;

iii) an output connection;

e) the first connection of the first AC source, the second connection of the second AC source, the first high voltage multiplier ground connection, and the second high voltage multiplier ground connection all electrically connected to an electrical ground;

f) the second connection of the first AC source electrically connected to the first high voltage multiplier AC connection;

g) the first connection of the second AC source electrically connected to the second high voltage multiplier AC connection; and

h) the first high voltage multiplier output connection electrically connected to the second high voltage multiplier output connection.

16. The power supply of claim 15 wherein a DC voltage differential between the ground and the high voltage multiplier output connections is at least 10 kilovolts.

17. The power supply of claim 15 further comprising an x-ray tube including:

a) an evacuated insulative cylinder;

b) an anode disposed at one end of the insulative cylinder including a material configured to produce x-rays in response to impact of electrons; and

c) a cathode disposed at an opposing end of the insulative cylinder from the anode;

d) the power supply providing at least 10 kilovolts of DC voltage between the cathode and the anode; and

e) electrons accelerated from the cathode towards the anode in response to an electric field between the cathode and the anode, the electric field generated by the at least 10 kilovolts of DC voltage between the cathode and the anode.

18. The power supply of claim 15 wherein the high voltage multipliers are Cockcroft Walton multipliers.

19. The power supply of claim 15 wherein the first AC source is configured to be operated in phase with the second AC source.

20. The power supply of claim 15 wherein a phase difference between the first AC source and the second AC source is less than or equal to ninety degrees.