X-ray source and the use thereof and method for producing X-rays

Abstract

An x-ray source comprising a housing, in which a target in the form of an ionized cloud based on metal vapor is provided. The ionized cloud can be excited by means of an electron beam for emitting monochromatic x-rays. The low atom density advantageously produces only a little braking radiation. The robustness of the plasma with respect to the inevitable thermal energy input is also advantageous with respect to the solid target materials. The cloud can be filled at any time with target material which can be vaporized by means of an electric arc. A method for producing x-rays with the above-mentioned x-ray source is also provided. The use of an x-ray source for emitting monochromatic x-rays for x-raying a body is further provided.

Claims

1. An X-ray source having a housing, in which a target is provided that emits X-rays when being bombarded with an electron beam, wherein an ionized metal vapor is produced in the housing as the target, wherein a target material and a vaporizer apparatus for producing the metal vapor are provided in the housing; wherein an electrode is provided as the vaporizer apparatus for igniting an arc between the electrode and the target material.

2. The X-ray source as claimed in claim 1, wherein the housing has a vaporization chamber for a metal to be vaporized, the vaporization chamber being connected via an opening to a residual volume of the housing.

3. The X-ray source as claimed in claim 1, wherein the housing has a first window in a wall of the housing, the first window being transparent for the electron beam.

4. The X-ray source as claimed in claim 1, wherein a window is arranged in a wall of the housing, the window being transparent for the X-rays to be produced.

5. The X-ray source as claimed in claim 1, wherein the target material comprises a light metal.

6. The X-ray source as claimed in one of claim 1, wherein the target material comprises a lanthanide, tungsten, molybdenum or an alloy of at least two thereof.

7. A method comprising: utilizing an X-ray source emitting monochromatic X-rays as claimed in claim 1 for X-raying a body, which forms differentiable contrasts at a wavelength of the X-rays used.

8. The X-ray source as claimed in claim 2, wherein the opening is a nozzle.

9. The X-ray source as claimed in claim 5, wherein the target material is aluminum.

10. A method for producing X-rays, in which a target in a housing of an X-ray source is bombarded with an electron beam and emits X-rays, wherein a metal vapor is produced in the housing as the target in a vaporizer apparatus, wherein a target material is provided for producing the metal vapor; wherein an electrode is provided as the vaporizer apparatus for igniting an arc between the electrode and the target material.

11. The method as claimed in claim 10, wherein monochromatic X-rays are produced with the target.

Description

BRIEF DESCRIPTION

(1) Some of the embodiments will be described in detail, with reference to the following figures, wherein like designations denote like members, wherein:

(2) FIG. 1 shows an exemplary embodiment of the X-ray source in schematic section with a separate vaporization chamber and a housing for receiving the metal vapor; and

(3) FIG. 2 shows a further exemplary embodiment of the X-ray source in which the target material is vaporized and the cloud is received in that same housing body, in schematic section.

DETAILED DESCRIPTION

(4) Illustrated in FIG. 1 is an X-ray source, in which a housing 11 is provided, in which a cloud 12 of metal vapor can be produced as the target for X-rays 21. Adjacent to said housing 12 is a vaporization chamber 13, in which a liquid target material 14 is vaporized using an arc 15. The target material can be liquefied even before vaporization by the introduction of energy of the arc 15. In order to be able to ignite the arc 15, electrodes 16 and a voltage source 17 are provided. The vaporizer apparatus 18 formed by the vaporization chamber 13 is made complete by a nozzle 19, with said nozzle being formed in the partition between a production space 20, formed by the housing 11, for a monochromatic X-ray beam 21 and the vaporization chamber 13. The housing 11 is separated from the vaporization chamber 13 by an electrically insulating layer 22.

(5) In order to produce an electron beam 23, an electron gun 24 is provided, wherein the electron beam 23 passes into the housing 11. The electron beam interacts with the gaseous target and is electrostatically decelerated and collected by a collector 28. Finally, a window 29 is provided, through which the X-rays 21 which are produced can be coupled out of the housing 11.

(6) The electron gun 24 has a cathode 30, which is at a potential of 0 V. It emits the electron beam 23, which is, focused by a lens 31, coupled out of the electron gun. The driving force here is a potential which is established by the ionized, gaseous target to be made to have a potential of +100 to +300 kV. The collector 28 is at a potential of between +40 and +120 kV.

(7) FIG. 2 illustrates an alternative embodiment of the X-ray source. The housing 11 used here only has one housing space 33, which acts both as the vaporizer apparatus 18 and as the production space 20 according to FIG. 1. At the bottom of the housing 11 is the target material 14, which is likewise melted and vaporized by the electrodes 16 by way of the arc 15. As in FIG. 1, the electrodes 16 are electrically insulated from the remaining housing by insulators 34. The electrodes 16 according to FIG. 2 are supplied by an AC voltage source 35, wherein the arc is stabilized by a ballast 36. Stabilization of the arc is necessary so that the cloud used as the target is replenished continuously with vaporized target material. This is because the embodiment according to FIG. 2 lacks a metering apparatus like nozzle 19 according to FIG. 1.

(8) However, the X-ray beam 21 is produced in the same way as described in FIG. 1. This is also illustrated in more detail in FIG. 1. In this case, a lanthanum atom with its nucleus 56 is illustrated by way of example. Also illustrated is the K-shell 37 of the atom, on which an electron 38 is located. This electron is excited by excitation of the electron beam and raised to a higher shell 39. When it jumps back, it emits the monochromatic X-rays 21.

(9) The electron emitter used is, according to FIG. 2, not an electron gun 24 but a simple electrode 40, wherein this electrode 40 is, as already described in FIG. 1, at a potential of 0 V. Both the electrode 40 and the collector 28 are arranged in an external housing 41, which has an additional window 42, by way of which the X-rays 21 are coupled out. The housing 11 is simply placed inside the external housing 41. Advantageously, a plurality of the housings 11 can be kept in storage, for example in order to allow fast replacement if the housing 11 needs to be cleaned or if the target material 14 is used up. It is advantageously also possible for a plurality of housings with different target materials 14 to be kept in storage, so as to be in a position to quickly modify the X-ray source for producing monochromatic X-rays of different wavelengths. In principle, such modification is, of course, also possible in the construction according to FIG. 1.

(10) Although the present invention has been disclosed in the form of preferred embodiments and variations thereon, it will be understood that numerous additional modifications and variations could be made thereto without departing from the scope of the invention.

(11) For the sake of clarity, it is to be understood that the use of a or an throughout this application does not exclude a plurality, and comprising does not exclude other steps or elements.