Apparatus for Generating Electron Radiation and 3D Printing Apparatus

Abstract

An apparatus for generating electron radiation comprises a wire-shaped hot cathode that is much more extensive in a longitudinal direction than in a transverse direction. Electron radiation emerges from the hot cathode that, due to the elongated shape of the hot cathode, exhibits an elongated, line-shaped cross section perpendicular to its direction of propagation, where the extension in longitudinal direction of the line is significantly greater than in transverse direction of the line. The apparatus further comprises a cathode electrode and an anode. A voltage for accelerating the electrons emitted from the hot cathode is applied between the cathode electrode and the anode. The hot cathode is arranged to be spaced apart from the cathode electrode such that electrons that are accelerated to the anode are emitted from the hot cathode in each of the transverse directions.

Claims

1. An apparatus for generating electron radiation, comprising: a wire-shaped hot cathode that is much more extensive in a longitudinal direction than in a transverse direction perpendicular thereto, the hot cathode being configured to emit electron radiation exhibiting an elongated, line-shaped cross section perpendicular to its direction of propagation as a result of an elongated shape of the hot cathode, where an extent of the electron radiation in a longitudinal direction of the line-shaped cross section is significantly greater than in a transverse direction of the line-shaped cross section; a cathode electrode; an anode, wherein during operation of the apparatus, a voltage emitted from the hot cathode for accelerating electrons is applied between the cathode electrode and the anode, wherein the hot cathode is arranged so as to be spaced apart from the cathode electrode such that electrons accelerated to the anode are emitted from the hot cathode in each of a plurality of transverse directions.

2. The apparatus of claim 1, wherein the cathode electrode has a smooth surface and/or a non-interrupted surface on the side facing the hot cathode, wherein the surface is not interrupted by a groove.

3. The apparatus of claim 1, wherein the cathode electrode has a curved surface comprising a hollow cylindrical, concavely curved surface on a side facing the hot cathode.

4. The apparatus of claim 3, wherein the hollow cylindrical, concavely curved surface of the cathode electrode has a vertex line and comprises a surface with a parabola-shaped cross section.

5. The apparatus of claim 4, wherein the distance between the hot cathode and the surface of the cathode electrode in the region of the vertex line of the concave curvature at the extremum of the parabola is less than the distance between the hot cathode and other regions of the surface of the cathode electrode.

6. The apparatus of claim 1, wherein the electrons emitted from the hot cathode in the direction of the cathode electrode are reflected on the surface of or in the region of the surface of the cathode electrode in the direction of the anode or are deflected in the direction of the anode.

7. The apparatus of claim 1, wherein a workpiece to be machined serves as an anode.

8. The apparatus of claim 1, wherein the anode is configured an anode electrode that has an opening through which the electron radiation emerging from the hot cathode can pass.

9. The apparatus of claim 1, wherein the apparatus comprises a plurality of deflection electrodes to compress and/or focus the electrode radiation.

10. The apparatus of claim 9, wherein the deflection electrodes are arranged behind the anode electrode in the direction of propagation of the electron radiation.

11. A three-dimensional (3D) printing apparatus for producing a spatially extended product, comprising: at least one apparatus of claim 1 for generating electron radiation; and a working region, to which starting material, to be exposed to electron radiation, for the 3D printing is or can be fed, wherein the working region is arranged in the 3D printing apparatus such that the electron radiation impinges on the starting material.

12. An apparatus for machining a workpiece, comprising at least one apparatus of claim 1 for generating electron radiation.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Other features and advantages of the described apparatuses will become apparent from the following description of example embodiments with reference to the accompanying drawings.

[0022] FIG. 1 is, in schematic form, a side view of a first embodiment of an apparatus for generating electron radiation.

[0023] FIG. 2 is a perspective view of the apparatus according to FIG. 1.

[0024] FIG. 3 is, in schematic form, a side view of a second embodiment of an apparatus for generating electron radiation.

[0025] FIG. 4 is a perspective view of the apparatus according to FIG. 3.

[0026] FIG. 5 is, in schematic form, a side view of a third embodiment of an apparatus for generating electron radiation.

[0027] FIG. 6 is a perspective view of the apparatus according to FIG. 5.

[0028] FIG. 7 is, in schematic form, a side view of a fourth embodiment of an apparatus for generating electron radiation.

[0029] FIG. 8 is a perspective view of the apparatus according to FIG. 7.

[0030] FIG. 9 is, in schematic form, a side view of a fifth embodiment of an apparatus for generating electron radiation, wherein the generated electron radiation is illustrated.

[0031] FIG. 10 is an exploded view of a detail from FIG. 9.

[0032] FIG. 11 is an exploded view of a detail from FIG. 10.

[0033] FIG. 12 is, in schematic form, a side view of a first embodiment of an apparatus that is intended for generating electron radiation and that is designed as a Pierce electron gun.

[0034] FIG. 13 is a perspective view of the apparatus according to FIG. 12.

[0035] FIG. 14 is, in schematic form, a side view of a second embodiment of an apparatus that is intended for generating electron radiation and that is designed as a Pierce electron gun.

[0036] FIG. 15 is a perspective view of the apparatus according to FIG. 14.

[0037] FIG. 16 is, in schematic form, a side view of a third embodiment of an apparatus that is intended for generating electron radiation and that is designed as a Pierce electron gun, wherein the generated electron radiation is illustrated.

[0038] FIG. 17 is an exploded view of a detail from FIG. 16.

[0039] FIG. 18 is an exploded view of a detail from FIG. 17.

DETAILED DESCRIPTION

[0040] Identical or functionally identical parts or elements are provided with the same reference numerals in the figures.

[0041] The illustrated apparatuses comprise a hot cathode 11, a cathode electrode 12 and an anode electrode 13. The apparatus can generate electron radiation 14 (see FIG. 9 to FIG. 11).

[0042] In all of the embodiments, the hot cathode 11 is constructed as a wire and extends into the drawing plane of FIG. 1, FIG. 3, FIG. 5, FIG. 7, and FIGS. 9 to 11 or, more specifically, in a longitudinal direction that is arranged perpendicular to the direction of propagation of the electron radiation 14. Owing to this configuration, a line-shaped cross section of the electron radiation 14 is achieved, wherein the longitudinal direction of the line-shaped cross section is aligned parallel to the longitudinal direction of the wire forming the hot cathode 11.

[0043] In the illustrated embodiments, the anode electrode 13 comprises two parts 13a, 13b, which are spaced apart from one another and between which the electron radiation 14 can pass through. Instead of a multiple piece anode electrode 13, a single piece anode electrode 13 can also be provided. Then the single piece anode electrode may have an opening, through which the electron radiation 14, emerging from the hot cathode 12, can pass. The opening can be, in particular, rectangular and may have a much larger dimension in its longitudinal direction, which extends into the drawing plane of FIG. 1, than in its transverse direction, in order to let the line-shaped electron radiation 14 pass through.

[0044] The hot cathode 11 is supplied by a voltage source, which is not shown, with a voltage such that a current flows through the hot cathode 11 that causes the hot cathode 11 to heat up. In this case, the hot cathode 11 may be at least partially at the same potential as the cathode electrode 12.

[0045] When the apparatus is in operation, a voltage generated by a voltage source (not shown) and intended for accelerating the electrons emitted from the hot cathode 11 is applied between the cathode electrode 12 and the anode electrode 13. The voltage may be, for example, between 1 kV and 10 kV. In this case, the cathode electrode 12 is connected to the negative pole, and the anode electrode 13 is connected to the positive pole of the voltage source, wherein, in particular, the anode electrode 13 can additionally be connected to ground.

[0046] According to one option, the anode electrode can be dispensed with in the apparatus. In this case, a metallic workpiece that is to be machined can be used, for example, as an anode.

[0047] The cathode electrode 12 has a cavity 15 that is open on one side and in which the hot cathode 11 is disposed. The surface 16 of the cathode electrode 12 that forms the cavity 15 is smooth or, more specifically, not interrupted. The surface 16 is constructed so as to be hollow cylindrical and concavely curved, where in this case the surface 16 has, in particular, a parabola-shaped cross section. As a result, the concavely curved surface 16 of the cathode electrode 12 has a vertex line 17 that extends into the drawing plane in FIG. 11. The hot cathode 11 is disposed in front of the vertex line 17 or, more specifically, in front of the extremum of the parabola (see FIG. 1). In this case, the hot cathode 11 is at a distance from the surface 16 of the cathode electrode 12, where the distance is less in the region of the vertex line 17 or, more specifically, in the region of the extremum of the parabola than the distance between the hot cathode 11 and other regions of the surface 16 of the cathode electrode 12.

[0048] FIG. 11 shows that even the electrons emitted from the hot cathode 11 upwards in FIG. 11 or, more specifically, in the direction of the vertex line 17, are deflected downwards in the direction of the anode electrode 13. Therefore, when the apparatus is in operation, the electrons, emitted from the hot cathode 11 in the direction of the cathode electrode 12, are reflected on the surface 16 or in the region of the surface 16 of the cathode electrode 12 in the direction of the anode electrode 13 or are deflected in the direction of the anode electrode 13. In this way, it is ensured that in essence all of the electrons emitted from the hot cathode 11 in radial directions contribute to the electron radiation 14.

[0049] Furthermore, the embodiment according to FIGS. 1 and 2 comprises two deflection electrodes 18a, 18b behind the anode electrode 13 in the direction of propagation of the electron radiation 14. It is also possible to dispense with the two deflection electrodes 18a, 18b. They are used only to form the beam profile of the electron radiation 14.

[0050] Furthermore, the embodiments according to FIGS. 3 to 8 comprise in the direction of propagation of the electron radiation 14 behind the deflection electrodes 18a, 18b an additional electrode 19 that has an opening 20 for the passage of the electron radiation 14. The additional electrode 19 may have a positive potential with respect to the deflection electrodes 18a, 18b so that the electrons of the electron radiation 14 are accelerated in the direction of the additional electrode 19 and pass through the opening 20.

[0051] The individual embodiments are distinguished to some extent by the configuration of the anode electrode 13. In the embodiments in FIGS. 1 to 4, the anode electrode 13 comprises two flat, plate-shaped parts 13a, 13b, which are spaced apart from one another. The parts are inclined towards the horizontal in the drawings such that their mutually facing ends extend upwards into the cavity 15 of the cathode electrode 12.

[0052] In the embodiment according to FIGS. 5 and 6, the parts 13a, 13b are arranged in a similar way. However, they are not designed so as to be flat, but rather curved.

[0053] In the embodiments in FIGS. 7 to 11, the parts 13a, 13b are constructed so as to be flat, as in the first embodiments, according to FIGS. 1 to 4. However, they are not inclined towards the horizontal in the drawings, so that their mutually facing ends do not extend upwards into the cavity 15 of the cathode electrode 12.

[0054] The apparatus for generating electron radiation may be integrated in a 3D printing apparatus for the production of a spatially extended product. To this end, then for the 3D printing a bar-shaped starting material that is made of metal and that can be melted by the electron radiation 14 can be arranged, for example, in a working region 21 (see FIG. 9). As an alternative, a starting material in powder form can also be provided.

[0055] In the apparatuses described some or, in particular, all of the parts may be arranged in a vacuum. The housing required to this end is not shown or is not shown in its entirety in the figures. Only FIG. 9 shows a housing 22 in schematic form.