X-ray source with an immersion lens

1. An x-ray source, comprising:

an electron source configured to emit a beam of electrons;

a magnetic focusing lens configured to focus the beam of electrons to a spot, having a spot size, on a target, wherein the magnetic focusing lens includes an immersion lens in which a peak in a magnitude of a magnetic field associated with the magnetic focusing lens occurs proximate to a plane of the target;

an electrostatic lens between the electron source and the magnetic focusing lens that is configured to collimate the beam of electrons; and

the target configured to provide a transmission source of x-rays in response to receiving the beam of focused electrons.

2. The x-ray source of claim 1 , wherein the x-ray source further includes a tube that has a surface that defines an interior of the tube;

wherein the electron source and the target are included in the interior of the tube;

and

wherein the tube is sealed and the interior of the tube has a pressure that is less than atmospheric pressure.

3. The x-ray source of claim 2 , wherein the pressure in the interior of the tube is less than or equal to high vacuum.

4. The x-ray source of claim 2 , wherein the target includes a thin-film deposited on the surface of the tube.

5. The x-ray source of claim 1 , wherein the x-ray source further includes:

a power-supply circuit that is configured to provide power to the electron source and the magnetic focusing lens; and

an anti-arcing material that surrounds the power-supply circuit.

6. The x-ray source of claim 5 , wherein the power-supply circuit outputs a voltage between 10 kV and 500 kV.

7. The x-ray source of claim 1 , wherein the target includes: tungsten, tantalum, molybdenum, rhenium, copper or compounds that include two or more of these elements.

8. The x-ray source of claim 1 , wherein a focal length of the magnetic focusing lens is between 0.5 and 5 mm.

9. The x-ray source of claim 1 , wherein the spot size has a cross-sectional diameter between 10 nm and 100 μm.

10. The x-ray source of claim 1 , wherein a focal length of the electrostatic lens is between 0.5 and 50 mm.

11. An x-ray source, comprising:

an electron source configured to emit a beam of electrons;

a magnetic collimating lens configured to collimate the beam of electrons;

a magnetic focusing lens configured to focus the beam of electrons to a spot, having a spot size, on a target, wherein the magnetic focusing lens includes an immersion lens in which a peak in a magnitude of a magnetic field associated with the magnetic focusing lens occurs proximate to a plane of the target; and

the target configured to provide a transmission source of x-rays in response to receiving the beam of focused electrons.

12. The x-ray source of claim 11 , wherein the x-ray source further includes a tube that has a surface that defines an interior of the tube;

wherein the electron source and the target are included in the interior of the tube;

and

wherein the tube is sealed and the interior of the tube has a pressure that is less than atmospheric pressure.

13. The x-ray source of claim 12 , wherein the target includes a thin-film deposited on the surface of the tube.

14. The x-ray source of claim 11 , wherein a focal length of the magnetic focusing lens is between 0.5 and 5 mm.

15. The x-ray source of claim 11 , wherein the spot size has a cross-sectional diameter between 10 nm and 100 μm.

16. A system, comprising an x-ray source, wherein the x-ray source includes:

an electron source configured to emit a beam of electrons;

a magnetic focusing lens configured to focus the beam of electrons to a spot, having a spot size, on a target;

an electrostatic or magnetic collimating lens between the electron source and the magnetic focusing lens that is configured to collimate the beam of electrons; and

the target configured to provide a transmission source of x-rays in response to receiving the beam of focused electrons, wherein the magnetic focusing lens includes an immersion lens in which a peak in a magnitude of a magnetic field associated with the magnetic focusing lens occurs proximate to a plane of the target.

17. The system of claim 16 , wherein the x-ray source further includes a tube that has a surface that defines an interior of the tube;

wherein the electron source and the target are included in the interior of the tube; and

wherein the tube is sealed and the interior of the tube has a pressure that is less than atmospheric pressure.

18. The system of claim 17 , wherein the target includes a thin-film deposited on the surface of the tube.

19. The system of claim 16 , wherein the target includes: tungsten, tantalum, molybdenum, rhenium, copper or compounds that include two or more of these elements.

20. The system of claim 16 , wherein a focal length of the magnetic focusing lens is between 0.5 and 5 mm.

21. The system of claim 16 , wherein the spot size has a cross-sectional diameter between 10 nm and 100 μm.

22. A method for providing a transmission source of x-rays, the method comprising:

emitting a beam of electrons from an electron source;

collimating the beam of electrons with an electrostatic or magnetic collimating lens;

focusing, using a magnetic focusing lens after the electrostatic or magnetic collimating lens, the beam of electrons to a spot, having a spot size, on a target, wherein the magnetic focusing lens includes an immersion lens in which a peak in a magnitude of a magnetic field associated with the magnetic focusing lens occurs proximate to a plane of the target; and

in response to receiving the beam of focused electrons at the target, providing the transmission source of x-rays.