X-RAY TUBE HAVING AN INSULATION BODY WITH A POTTED BODY

Abstract

An X-ray tube has a cathode housing having a radiation exit window, a cooled anode, a hot cathode, an insulation body, a supply line for coolant to the anode and a discharge line for coolant from the anode. The supply and discharge lines have a plurality of turns in the insulation body. The potted body has an inner and outer mold. The anode, the cathode housing and the potted body are fastened on the ceramic body. At least one plastic directing body aligns the hoses separated from the outer and inner mold. The potting space is filled with a plastic potting compound in a cured state so that the intermediate spaces between the turns on the one hand and the outer mold and the inner mold on the other hand are occupied by the plastic of the at least one directing body and/or the plastic of the potting compound.

Claims

1. An X-ray tube, comprising: a cathode housing having a radiation exit window, a cooled anode, a cathode, an insulation body configured for electrical insulation of a high-voltage potential of the anode, a supply line configured for coolant to the anode, and a discharge line configured for coolant from the anode; the supply line and the discharge line respectively comprising a plurality of turns in the insulation body; wherein the insulation body comprises a ceramic body and a potted body; the anode and the cathode housing being fastened on the ceramic body and the potted body being fastened on the ceramic body; wherein the potted body comprises an inner mold and, at least temporarily during the production of the X-ray tube, an outer mold; wherein the supply line and the discharge line are respectively configured with a hose, which forms the plurality of turns, in a potting space between the outer mold and the inner mold; wherein at least one plastic directing body, by which the hoses are aligned in the potting space, is arranged in the potting space wherein the turns of the hoses are respectively separated from the outer mold and the inner mold; and wherein the potting space is filled with a plastic potting compound in a cured state wherein the intermediate spaces between the turns on the one hand and the outer mold and the inner mold on the other hand are occupied by the plastic of the at least one directing body and/or the plastic of the potting compound.

2. The X-ray tube as claimed in claim 1, wherein with the at least one directing body, the hoses are furthermore aligned in the potting space wherein the turns of the hoses are also separated from one another, and wherein the potting space is furthermore filled with the potting compound wherein the intermediate spaces between the turns are also occupied by the plastic of the at least one directing body and/or the plastic of the potting compound.

3. The X-ray tube as claimed in claim 1, wherein the ceramic body has a circumferential indentation between the cathode housing and the anode on a front side facing toward the anode, and wherein the ceramic body has a central recess on a rear side of the ceramic body facing toward the potted body.

4. The X-ray tube as claimed in claim 3, wherein the hoses are arranged partially in a region of the central recess of the ceramic body, in particular with in each case at least one half-turn of the hoses and/or at least 10% of the length of the hoses being arranged in the central recess of the ceramic body.

5. The X-ray tube as claimed in claim 1, wherein the inner mold is configured as a bush for a high-voltage plug for connection to the anode.

6. The X-ray tube as claimed in claim 1, wherein the inner mold is configured as a cable which comprises an insulating sheath and a core running in the sheath, to which the anode is connected.

7. The X-ray tube as claimed in claim 1, wherein the at least one directing body and the potting compound consist of the same plastic.

8. The X-ray tube as claimed in claim 7, wherein the plastic of the potting compound comprises a silicone or an epoxy resin or a polyurethane.

9. The X-ray tube as claimed in claim 1, wherein a plurality of directing bodies is arranged in the potting space, in particular with the directing bodies in each case being arranged clamped between the inner mold and the outer mold and/or between the hoses on the one hand and the inner mold or the outer mold on the other hand.

10. The X-ray tube as claimed in claim 9, wherein the directing bodies are arranged at angular positions in a respective section plane perpendicular to a tube axis (RA) of the X-ray tube, the angular positions forming a rotationally symmetrical arrangement with respect to the tube axis (RA).

11. The X-ray tube as claimed in claim 10, wherein N directing bodies support the hoses toward the inner mold and N directing bodies support the hoses toward the outer mold, and the rotationally symmetrical arrangement of the angular positions has N-fold symmetry, where N is a natural number with N≥2.

12. The X-ray tube as claimed in claim 11, wherein the N directing bodies which support the hoses toward the inner mold and the N directing bodies which support the hoses toward the outer mold are arranged with respect to the tube axis (RA) in a respective section plane at identical angular positions, or at angular positions offset by 360°/(2*N) with respect to one another.

13. The X-ray tube as claimed claim 1, wherein one or more directing bodies of the at least one directing body are configured as a perforated plate comprising a plate and a plurality of holes in the plate, through which the hoses are guided, in particular with a respective perforated plate being arranged clamped between the inner mold and the outer mold.

14. The X-ray tube as claimed in claim 1, wherein one or more directing bodies of the at least one directing body are configured as a grooved bar comprising a bar and a plurality of grooves, in particular semicircular grooves, into which the hoses are placed, in particular, with a respective grooved bar being arranged clamped between the hoses on the one hand and the inner mold or the outer mold on the other hand.

15. The X-ray tube as claimed in claim 14, wherein grooved bars which support hoses toward the inner mold and grooved bars which support hoses toward the outer mold are respectively arranged lying opposite one another pairwise.

16. The X-ray tube as claimed claim 1, wherein the turns of the hoses are wound around a tube axis (RA) and are sequenced along a tube axis (RA).

17. The X-ray tube as claimed in claim 16, wherein the turns have a constant radius (R) with respect to the tube axis (RA).

18. The x-ray tube according to claim 17, with the outer mold and the inner mold being configured substantially in the form of the lateral surface of a cylinder and coaxially with respect to the tube axis (RA) and the turns having a constant radial spacing (RAA) with respect to the outer mold and furthermore the turns have a constant radial spacing (RAI) with respect to the inner mold.

19. The X-ray tube as claimed in claim 17, wherein the turns have a constant spacing (AA) with respect to one another in the axial direction.

20. The X-ray tube as claimed in claim 16, wherein the turns have a radius (R) with respect to the tube axis (RA) which increases away from the anode.

21. The X-ray tube as claimed in claim 20, with the outer mold and the inner mold being configured substantially in the form of the lateral surface of a cylinder and coaxially with respect to the tube axis (RA) and the turns having a radial spacing (RAA) with respect to the outer mold which decreases away from the anode and furthermore the turns having a radial spacing (RAI) with respect to the inner mold which increases away from the anode.

22. The X-ray tube as claimed in claim 20, wherein the turns have a constant axial spacing (AA) with respect to one another or an axial spacing (AA) with respect to one another which increases away from the anode.

23. The X-ray tube as claimed in claim 1, wherein after the production of the X-ray tube, the outer mold remains on the rest of the potted body.

24. The X-ray tube as claimed in claim 1, wherein after the production of the X-ray tube, the outer mold is removed from the rest of the potted body.

25. The X-ray tube as claimed in claim 1, wherein the cathode is a hot cathode.

26. A method for producing the X-ray tube as claimed in claim 1, the method comprising the steps of: a) in order to set up the potting space, arranging the outer mold in a sealing manner on a rear side of the ceramic body facing away from the anode and arranging the inner mold in front of the rear side of the ceramic body, and arranging the at least one plastic directing body and the hoses in the potting space between the inner mold and the outer mold, with the at least one directing body aligning the hoses in the potting space wherein the turns of the hoses are respectively separated from the outer mold and the inner mold; b) filling the potting space with the plastic potting compound in a liquid state wherein the intermediate spaces between the turns on the one hand and the outer mold and the inner mold on the other hand are occupied by the plastic of the at least one directing body and/or the plastic of the potting compound; and c) curing the plastic potting compound.

27. The method as claimed in claim 26, wherein the X-ray tube is produced wherein the outer mold is remaining on the rest of the potted body after step c).

28. The method as claimed in claim 26, wherein the X-ray tube is produced comprising a further step d) of removing the outer mold from the rest of the potted body.

29. The method as claimed in claim 26, wherein the turns of the hoses are also separated from one another, and wherein the intermediate spaces between the turns are also occupied by the plastic of the at least one directing body and/or the plastic of the potting compound when filling the potting space with the plastic potting compound in the liquid state.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0062] FIG. 1 shows a schematic longitudinal section of a first embodiment of an X-ray tube according to the invention, having grooved bars and turns of the hoses with a uniform radius;

[0063] FIG. 2 shows a schematic longitudinal section of a second embodiment of an X-ray tube according to the invention, having perforated plates and turns of the hoses with a uniform radius;

[0064] FIG. 3 shows a schematic longitudinal section of a third embodiment of an X-ray tube according to the invention, having grooved bars and turns of the hoses with a variable radius and a crown-shaped ceramic body;

[0065] FIG. 4 shows a schematic longitudinal section of a fourth embodiment of an X-ray tube according to the invention, having perforated plates and turns of the hoses with a variable radius and variable axial spacing;

[0066] FIG. 5 shows a schematic cross section through an X-ray tube according to the invention, having directing bodies at angular positions with a rotationally symmetrical arrangement of the angular positions, with two inner grooved bars and two outer grooved bars opposing one another;

[0067] FIG. 6 shows a schematic cross section through an X-ray tube according to the invention, having directing bodies at angular positions with a rotationally symmetrical arrangement of the angular positions, with four inner grooved bars and four outer grooved bars opposing one another;

[0068] FIG. 7 shows a schematic cross section through an X-ray tube according to the invention, having directing bodies at angular positions with a rotationally symmetrical arrangement of the angular positions, with two inner grooved bars being arranged offset by 90° with respect to two outer grooved bars;

[0069] FIG. 8 shows a schematic cross section through an X-ray tube according to the invention, having directing bodies at angular positions with a rotationally symmetrical arrangement of the angular positions, with three perforated plates being arranged offset by 120° with respect to one another;

[0070] FIG. 9 shows a schematic longitudinal section of a partially manufactured X-ray tube, having a cathode housing and a ceramic body, which is manufactured according to the invention to form a complete X-ray tube;

[0071] FIG. 10 shows the partially manufactured X-ray tube of FIG. 9, having a positioned inner mold and outer mold which form a potting space, having positioned directing bodies and positioned hoses;

[0072] FIG. 11 shows the X-ray tube of FIG. 10, now fully completed, the potting space being filled with a potting compound; and

[0073] FIG. 12 shows the X-ray tube of FIG. 11 in a variant of the invention, after removal of the outer mold.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0074] FIG. 1 shows a first embodiment of an X-ray tube 1 according to the invention in a schematic longitudinal section. The X-ray tube 1 extends along a tube axis RA.

[0075] The X-ray tube 1 comprises a cathode housing 2 which is fastened vacuum-tightly on a ceramic body 3, for example by soldering. An anode 4 (here having an approximately cylindrical anode body) which is likewise fastened vacuum-tightly on the ceramic body 3, typically likewise by soldering, is furthermore arranged inside the cathode housing 2. The cathode housing 2, the ceramic body 3 and the anode 4 delimit an evacuated space 5.

[0076] Arranged in the evacuated space 5 there is a cathode, here a hot cathode 6, typically formed with electrical filaments. In the embodiment shown, the hot cathode 6 can receive an electrical current via a ground terminal 7a and a current terminal 7b, which are fed vacuum-tightly through the cathode housing 2. The electrical current is typically an AC current, preferably with a low voltage, usually with a maximum voltage amplitude of 24 V or less. With this electrical current (also referred to as a heating current), the hot cathode 6 can be brought to incandescence so that electrons emerge from the hot cathode 6.

[0077] During operation, the anode 4 is at a positive high-voltage potential (typically from 20 kV to 60 kV, in other applications possibly even more), relative to the hot cathode 6. During operation in the embodiment shown here, the hot cathode 6 is grounded, notwithstanding the heating current explained above. Electrons emerging from the hot cathode 6 are accelerated by the high voltage, under the effect of a grounded shield 8, from the hot cathode 6 onto the anode 4, here onto an upper side 4a of the anode 4. When they impinge on the anode 4, the electrons are decelerated so that X-radiation is generated in the form of Bremsstrahlung. Furthermore, electrons are ejected from the inner shells of the atoms of the material (“target”) arranged on the upper side 4a of the anode 4. When electrons from the outer shells fill the inner shells of these atoms, X-radiation is emitted in the form of characteristic X-radiation. In general, a desired material is applied on the upper side 4a of the anode 4 in order to generate the X-radiation characteristic of this material. The X-radiation generated emerges from the X-ray tube 1 through a radiation exit window 13, here a beryllium window, and can be used for measurements, for example an X-ray fluorescence measurement on a sample, or for the recording of an X-ray image.

[0078] The electrons which are accelerated onto the anode 4 heat the anode 4, which consists of metal. In order to prevent melting of the anode 4, the anode 4 is cooled with a coolant. Formed in the X-ray tube 1 there is a supply line 9, which conducts the coolant to the anode 4, and furthermore a discharge line 10 which conducts the coolant back away from the anode 4. It should be noted that the supply line 9 and the discharge line 10 may also be connected the other way round to the coolant flow, if so desired.

[0079] The anode 4, which is at a high-voltage potential, must be electrically insulated. In particular, voltage flashovers onto the outer side of the X-ray tube 1 and other grounded structures must be prevented.

[0080] The electrical insulation of the anode 4 is carried out on the X-ray tube 1 essentially by an insulation body 11 and the evacuated space 5 set up in the cathode housing 2. According to the invention, this insulation body 11 comprises the ceramic body 3 made of ceramic material, on which the anode 4 and the cathode housing 2 are seated, and a potted body 12 which is fastened to the ceramic body 3 on the rear side. The ceramic body 3 consists of a vacuum-tight ceramic material, for example Al.sub.2O.sub.3. The potted body 12 consists to a substantial part of a plastic potting compound 32. The plastic of the potting compound 32 may, for example, be a silicone. The supply line 9 and the discharge line 10 are fed through the insulation body 11 to the anode 4. The insulation body 11 (and correspondingly also the respectively associated section of the ceramic body 3 and the housing body 12) is configured approximately in the shape of a circular cylinder on the outside and aligned along the tube axis RA.

[0081] It should be noted that the coolant is in contact with the high-voltage potential in the anode 4 and is grounded in the region of coolant connections 9b, 10b. Correspondingly, the high voltage drops in the coolant over the length of the supply line 9 and over the length of the discharge line 10. In order to prevent sparkovers of the high voltage, on the one hand a coolant having a low electrical conductivity or high dielectric strength is used, for example deionized water or a silicone oil. On the other hand, the X-ray tube 1 is designed in such a way that it allows a large length (path length) of the supply line 9 and the discharge line 10 in a compact space and furthermore ensures sufficient separation of structures that are at different electrical potentials.

[0082] In the design shown, two tubelets 14a, 14b, typically made of metal, lead through the ceramic body 3, to which at the upper end anode channels 4b for the coolant, which run within the anode 4, are connected and to which at the lower end hoses 9a, 10a are connected. It should be noted that in other designs, the coolant feed through the ceramic body 3 may also be configured differently, for example with coaxial tubelets or ceramic tubelets, or simple holes, into which plug connections (not represented) are inserted. The hoses 9a, 10a form the supply line 9 and the discharge line 10, insofar as they run within the potted body 12. The hoses 9a, 10a are made from a plastic material. In the potted body 12, the hoses 9a, 9b respectively form a plurality of turns 16 in a central section, which are arranged successively in the axial direction and form a double helix in this region (more on this below).

[0083] On its rear side facing away from the anode 4, the ceramic body 3 forms a central recess 15, which is configured conically here. In the axial direction (along the tube axis RA), the recess 15 extends over a depth TR into the ceramic body 3, which in total has an axial extent AEK. In the embodiment shown, TR=0.8*AEK approximately applies; in general, preferably, TR 0.5*AEK or even TR 0.75*AEK. In the radial direction (perpendicularly to the tube axis RA), the recess 15 extends at its widest point on the rear side of the ceramic body 3 with a maximum radius GRR, and at its end near the anode at its narrowest point with a minimum radius KRR. The ceramic body 3 has an outer radius RK in the region of its rear side; it should be noted that in the embodiment shown, the ceramic body 3 has a uniform outer radius. In the embodiment shown, GRR=0.75*RK approximately applies; in general, preferably, GRR 0.5*RK or even GRR 0.67*RK. Furthermore, in the embodiment shown KRR=0.53*RK approximately applies; in general, preferably, KRR 0.33*RK or even KRR 0.40*RK.

[0084] By the recess 15 in the ceramic body 3, the hoses 9a, 10a can be brought axially close to the anode 4, and the depth TR of the recess 15 can at least partially be used to make the high voltage drop across the coolant in the hoses 9a, 10a. The tubelets 14a, 14b, by which the anode channels 4b are connected to the hoses 9a, 10a, can be configured to be comparatively short. A considerable hose length, usually at least 10% of the respective overall hose length or even a hose length corresponding to at least a half-turn 16 (i.e., at least R*pi, with R: radius of the turns 16), can be accommodated in the region of the recess 15. The recess 15 furthermore leads to a comparatively long creepage path from the tubelets 14a, 14b to the radial outer side of the ceramic body 3 along the interface with the potted body 12, which, in particular, is much longer than the radius RK of the ceramic body 3.

[0085] A metal contacting element 17, which connects the anode 4 to a terminal pole 18, is also fed through the ceramic body 3. The contacting element 17 furthermore extends centrally in the X-ray tube 1 through the potted body 12 and, in the embodiment shown, leads into a bush 19 for a high-voltage plug (the latter is not represented) with which the high voltage for the anode 4 can be connected to the terminal pole 18 in the bush 19. The bush is made from an electrically insulating material, for example a plastic.

[0086] Here, the bush 19 at the same time forms an inner mold 20 for the potted body 12. The bush 19 is configured approximately cylindrically and is aligned with the tube axis RA.

[0087] The potted body 12 furthermore comprises an outer mold 21, which is configured here as a cylinder tube which may for example be made from metal or plastic. The inner mold 20, the outer mold 21 and the ceramic body 3 delimit a potting space 22. In particular, the hoses 9a, 10a run within this potting space 22.

[0088] The hoses 9a, 10a are aligned in the potting space 22 with the aid of directing bodies 23. The directing bodies 23 consist of plastic. Typically, the directing bodies 23 are arranged clamped in the potting space 22. In the embodiment shown, the directing bodies 23 are configured as grooved bars 24. The grooved bars 24 respectively comprise a bar 24a on which a plurality of grooves 24b, here semicircular grooves, are formed. A turn 16 of a hose 9a, 10a is placed into each groove 24b. In the embodiment shown, radially inner grooved bars 25a, 25b and radially outer grooved bars 26a, 26b, between which the turns 16 of the hoses 9a, 10a are clamped, respectively face one another. The grooved bars 24 are correspondingly clamped respectively between one of the molds 20, 21 and the hoses 9a, 10a.

[0089] By the directing bodies 23, the turns 16 of the hoses 9a, 10a are aligned with a high accuracy. In this case, both the spacing of the individual turns 16 radially inward with respect to the bush 19/inner mold 20 (RAI), and radially outward with respect to the outer mold 21 (RAA), and in the axial direction with respect to one another (AA) are set. In this case, in the embodiment shown, in the region of the turns 16 it is ensured that the neighboring turns 16 of the various hoses 9a, 10a, and furthermore the hoses 9a, 10a and the inner mold 20, and lastly the hoses 9a, 10a and the outer mold 21, do not touch (i.e., AA>0, RAI>0, RAI>0). In the embodiment shown, for all the turns 16 the radial spacing RAI inward with respect to the inner mold 20 is respectively the same, furthermore the radial spacing RAA outward with respect to the outer mold 21 is respectively the same, and furthermore the radius R of the turns 16 with respect to the tube axis RA is the same. In addition, the axial spacing AA with respect to one another is respectively the same for all the turns 16.

[0090] The potting space 22 has been filled with a liquid plastic potting compound 32, so that the entire potting space 22 that has not been occupied by other structures (hoses 9a, 10a, directing bodies 23, contacting element 17) has been filled with the potting compound 32. The directing bodies 23 have ensured that the hoses 9a, 10a could not be displaced during the potting and during the subsequent curing of the potting compound 32, and, in particular, the spacings provided (for example RAI, RAA, AA for the respective turns 16), which are relevant for the breakdown strength, have been maintained with a high accuracy. The plastic of the potting compound 32 and the plastic of the directing bodies 23 have been selected to be the same, in particular, as a silicone material. In this way, creepage currents at the interfaces between directing bodies 23 and the potting compound 32 are minimized; this interface (insofar as it relates to the electrical properties) substantially vanishes after the curing of the potting compound 32.

[0091] The potted body 12 engages with a conical front end 29 into the recess 15 of the ceramic body 3 and is fastened thereto. The X-ray tube 1 can establish a good vacuum tightness and high-voltage strength with the ceramic body 3, and with the potted body 12 a good water-tightness and likewise a good high-voltage strength, in a compact space. The potting compound 32 is straightforward to handle and is maintenance-friendly (in particular, the cured potting compound 32 can no longer flow out of the potting space 22 and exhibits only little thermal expansion and aging, unlike an insulation oil). A long coolant column can be set up (path length of the supply line and discharge line), in particular, by using installation space axially and radially inside the ceramic body 3. The hoses 9a, 10a may for this purpose have a certain flexibility, although this can be defined because of the directing bodies 23 and can be placed with the required spacings in the potted body 12. Creepage paths can readily be set up with a large length (for instance between the potted body 12 and the ceramic body 3) or can be entirely avoided (by the same plastic for the directing bodies 23 and the potting compound 32). Overall, a straightforward and compact structure of the X-ray tube 1 is possible, voltage flashovers being reliably avoidable and the coolant flow being ensured in a defined and reliable way.

[0092] It should be noted that with the X-ray tube 1, the outer mold 21 may also (after the potting of the potting compound and its curing) be removed (not represented in detail in FIG. 1, but cf. FIG. 12 back).

[0093] Further embodiments of an X-ray tube 1 according to the invention, which correspond substantially to the embodiment of FIG. 1, will be explained in FIGS. 2 to 4. Only the substantial differences from the embodiment of FIG. 1 will respectively be explained.

[0094] FIG. 2 shows a second embodiment of an X-ray tube 1 according to the invention.

[0095] In this X-ray tube 1, the directing bodies 23 for the hoses 9a, 10a are configured as perforated plates 27. The perforated plates 27 are respectively formed by a plate 27a which contains a plurality of holes 27b. The turns 16 of the hoses 9a, 10a are fed through the holes 27b. The perforated plates 27 are typically arranged clamped between the inner mold 20 and the outer mold 21, in particular, during the potting and curing of the potting compound. As an alternative, the perforated plates 27 may also be aligned relative to the rest of the X-ray tube 1 by an external holder during the potting and curing.

[0096] FIG. 3 shows a third embodiment of an X-ray tube 1 according to the invention.

[0097] In this embodiment, the ceramic body 3 is formed with a circumferential indentation 30 on its front side facing toward the anode 4. This indentation 30 lies radially between the anode 4 and the cathode housing 2. A creepage path from the anode 4 to the outer side of the ceramic body 3 at the interface of the ceramic body 3 and the evacuated space 5 is thereby extended, and in particular is significantly longer than the spacing AAG between the anode 4 and the cathode housing 2. The circumferential indentation 30 appears approximately V-shaped (in other embodiments, also U-shaped, not represented) in longitudinal section on each side of the tube axis RA. In longitudinal section, the ceramic body 3 appears approximately W-shaped overall, or in a three-dimensional view approximately crown-shaped.

[0098] In the embodiment shown, a cable 31 which is formed by a plastic insulating sheath 31a and a metal core 31b is used as the inner mold 20. The core 31b is connected to the contacting element 17 so that the anode 4 can receive a high voltage via the core 31b. The insulating sheath 31a protrudes here into the potted body 12 in the axial direction (along the tube axis RA) beyond the turns 16. The sheath 31a is configured with a constant diameter, and the cable 31 is aligned along the tube axis RA. During the potting of the potting space 22, the cable 31 is potted permanently into the X-ray tube 1.

[0099] In this embodiment, corresponding directing bodies 23 furthermore ensure that the radial spacing RAA of the turns 16 of the hoses 9a, 10a outward with respect to the outer mold 21 decreases away from the anode 4. Conversely, the radial spacing RAI of the turns 16 of the hoses 9a, 10a inward with respect to the inner mold 20 increases away from the anode 4. In the supply line 9 and in the discharge line 10, the (local) potential is commensurately higher when a respective line section lies closer to the anode 4 (along the line path of the supply line 9 or of the discharge line 10). The effect achieved with this configuration is therefore that the radial spacing of line sections with a high potential from the outer mold 21 (in contact with the ground) is greater than in line sections with a low potential. Conversely, it also achieves the effect that the radial spacing of line sections with a low potential from the core 31b (which is at a high voltage) is greater than for line sections with a high potential. This prevents voltage flashovers and allows a particularly compact build of the X-ray tube 1 for a given high voltage.

[0100] The directing bodies 23 in this design are configured as wedge-shaped grooved bars 24, and the turns 16 have an equal axial spacing AA with respect to one another.

[0101] FIG. 4 shows a fourth embodiment of an X-ray tube 1 according to the invention.

[0102] In this embodiment, the directing bodies 23 are again configured in such a way that the radial spacing RAA of the turns 16 of the hoses 9a, 10a outward with respect to the outer mold 21 decreases away from the anode 4. Conversely, the radial spacing RAI of the turns 16 of the hoses 9a, 10a inward with respect to the inner mold 20 increases away from the anode 4. In addition, it is provided here that the axial spacing AA of neighboring turns 16 increases away from the anode 4. Because of the increase in the radii R of the respective turns 16 in the direction axially away from the anode 4, there is a higher voltage drop per turn 16 for turns 16 which are further away from the anode 4 than for turns 16 which lie closer to the anode 4. By the larger axial spacings AA for the turns 16 which lie further away from the anode 4, voltage flashovers between axially neighboring turns 16 can therefore be prevented and a more compact build of the X-ray tube 1 can be achieved.

[0103] FIGS. 5 to 8 show schematic cross sections through X-ray tubes according to the invention perpendicularly to the respective tube axis RA in various embodiments, respectively in the region of the turns 16 and the directing bodies 23. In this case, the arrangement of angular positions at which the respective directing bodies 23 may advantageously be arranged in the potting space 22 between the outer mold 21 and the inner mold 20 is illustrated by way of example. The location or the projection of the hoses 9a, 10a is respectively represented by dashes.

[0104] In the embodiment of FIG. 5, the directing bodies 23 are configured as grooved bars 24, two (N=2) inner grooved bars 25a, 25b and two (N=2) outer grooved bars 26a, 26b being provided. An inner grooved bar 25a, 25b and an outer grooved bar 26a, 26b respectively oppose one another and clamp the hoses 9a, 10a between them. The inner grooved bars 25a, 25b are supported on the inner mold 20. The outer grooved bars 26a, 26b are supported on the outer mold 21. The angular positions of the two inner grooved bars 25a, 25b are offset by 180° with respect to one another, and the angular positions of the outer grooved bars 26a, 26b are offset by 180° with respect to one another. The arrangement of the angular positions of the directing bodies 23 has 2-fold rotational symmetry here.

[0105] In the embodiment of FIG. 6, the directing bodies 23 are likewise configured as grooved bars 24, four (N=4) inner grooved bars 25a, 25b, 25c, 25d and four (N=4) outer grooved bars 26a, 26b, 26c, 26d being provided. An inner grooved bar 25a, 25b, 25c, 25d and an outer grooved bar 26a, 26b, 26c, 26d respectively oppose one another and clamp the hoses 9a, 10a between them. The inner grooved bars 25a, 25b, 25c, 25d are supported on the inner mold 20. The outer grooved bars 26a, 26b, 26c, 26d are supported on the outer mold 21. The angular positions of the four inner grooved bars 25a, 25b, 25c, 25d are offset by 90° with respect to one another, and the angular positions of the outer grooved bars 26a, 26b, 26c, 26d are offset by 90° with respect to one another. The arrangement of the angular positions of the directing bodies 23 has 4-fold rotational symmetry here.

[0106] In the embodiment of FIG. 7, the directing bodies 23 are again configured as grooved bars 24, two (N=2) inner grooved bars 25a, 25b and two (N=2) outer grooved bars 26a, 26b being provided. The inner grooved bars 25a, 25b are supported on the inner mold 20. The outer grooved bars 26a, 26b are supported on the outer mold 21. The angular positions of the two inner grooved bars 25a, 25b are offset by 180° with respect to one another, and the angular positions of the outer grooved bars 26a, 26b are offset by 180° with respect to one another. The angular positions of the inner grooved bars 25a, 25b are in this case offset by 90° relative to the angular positions of the outer grooved bars 26a, 26b. The hoses 9a, 10a are also held clamped by the directing bodies 23 here; in this embodiment, the hoses 9a, 10a should have a certain minimum stiffness against radial compression and stretching (against “oval deformation”), so that a good clamping action of the directing bodies 23 occurs. The arrangement of the angular positions of the directing bodies 23 has 2-fold rotational symmetry here.

[0107] It should be noted that the grooved bars 24 may extend parallel to the tube axis RA, in which case the grooves must be fitted into the respective bar with an inclination corresponding to the pitch of the double helix of the hoses 9a, 10a. As an alternative, the grooved bars 24 may also extend with grooves fitted perpendicularly to their extent direction, and then be arranged with an inclination with respect to the tube axis RA in the potting space 12 which corresponds to the pitch of the hoses 9a, 10a. It should furthermore be noted that the inner grooved bars 25a-25d may be supported not only on the inner mold 20 but, as an alternative or in addition, also on one another, in particular with the inner grooved bars 25a-25d forming partial shells (in particular half-shells or quarter-shells) which engage around the inner mold (not represented in detail here).

[0108] In the embodiment of FIG. 8, the directing bodies 23 are configured as perforated plates 27, three (N=3) perforated plates 28a, 28b, 28c being provided, the angular positions of which are offset by 120° with respect to one another. The perforated plates 27 are respectively supported with their plates 27a (or the lateral edges thereof) both on the inner mold 20 and on the outer mold 21. The hoses 9a, 10a are fed through the holes 27b of the plates 27a. The arrangement of the angular positions of the directing bodies 23 has 3-fold rotational symmetry here.

[0109] FIGS. 9 to 11 schematically illustrate the sequence of the manufacture of an X-ray tube 1 according to the invention. By way of example, an X-ray tube 1 as described in FIG. 1 is manufactured. Longitudinal sections along the tube axis RA are respectively represented schematically.

[0110] The manufacture begins with the provision of a partially manufactured X-ray tube 100, essentially comprising the ceramic body 3 on which the anode 4 and the cathode housing 2 are already fastened, cf. FIG. 9. The cathode housing 2 is in this case directed downward.

[0111] The potting space 22 is then prepared by (in principle in any desired order): putting the outer mold 21 on the ceramic body 3; placing the inner mold 20 (here a bush 19 including a terminal pole 18) inside the outer mold 21; and arranging the directing bodies 23 and the hoses 9a, 10a in the region between the inner mold 20 and the outer mold 21. The state then reached is shown in FIG. 10. The hoses 9a, 10a are held in position by the directing bodies 23, here the grooves 24b. The potting space 22 is open upward.

[0112] The potting space 22 is then filled with a curable liquid potting compound 32 made of plastic, which for example is selected as a silicone. The potting compound 32 is most simply poured into the potting space 22 from above. The liquid potting compound 32 is distributed throughout the entire available potting space 22 up to a surface 32a of the potting compound 32. The potting compound 32 enters in particular, between the turns 16 and the inner mold 20, between the turns 16 and the outer mold 21, and axially between neighboring turns 16. The potting compound 32 thus encloses the hoses 9a, 10a as well as the directing bodies 23. The filled state of the potting space 22 is shown in FIG. 11. The liquid potting compound 32 is then cured; for the curing, typically a certain time is waited and/or heat is applied. After the curing of the potting compound 32, the potted body 12 and the X-ray tube 1 overall are completed. In this variant, the outer mold 21 remains on the X-ray tube 1; the outer mold 21 may be clad with lead foil (not represented) for grounding and radiation protection. With an anode 4 cooled by means of a coolant, for example deionized water, in the hoses 9a, 10a and a high voltage applied between the anode 4 and the heated hot cathode 6, X-radiation may then be generated by means of the X-ray tube 1 during operation.

[0113] In another variant, starting from the X-ray tube shown in FIG. 11, the outer mold of the potted body is removed after the curing of the potting compound 32; a corresponding X-ray tube 1 with a removed outer mold is represented in FIG. 12. Of the potted body, a residual potted body 12a, which is formed essentially by the potting space 22 filled with cured potting compound 32 (including the encapsulated directing body or bodies and the encapsulated hose sections) and the inner mold 20, then remains in the X-ray tube 1. A (radially outer) side face 32b of the cured potting compound 32, or of the filled potting space 22, is correspondingly exposed; this side face 32b may be clad with a lead foil (not represented) for grounding and radiation protection. In this variant, the outer mold may be used several times (it is then usually configured in multiple parts for radial mold release and arranged permanently on a potting station, not represented). The X-ray tube 1 shown in FIG. 12 may be used in the same way as the X-ray tube shown in FIG. 11 for the generation of X-radiation during operation.

LIST OF REFERENCE SIGNS

[0114] 1 X-ray tube [0115] 2 cathode housing [0116] 3 ceramic body [0117] 4 anode [0118] 4a upper side of the anode (“target”) [0119] 4b anode channels for coolant (in the anode body) [0120] 5 evacuated space [0121] 6 hot cathode [0122] 7a ground terminal [0123] 7b current terminal (for heating current) [0124] 8 shield [0125] 9 supply line [0126] 9a hose of the supply line [0127] 9b coolant connection (supply line) [0128] 10 discharge line [0129] 10a hose of the discharge line [0130] 10b coolant connection (discharge line) [0131] 11 insulation body [0132] 12 potted body [0133] 12a rest of the potted body [0134] 13 radiation exit window, here beryllium window [0135] 14a tubelet of the supply line [0136] 14b tubelet of the discharge line [0137] 15 recess [0138] 16 turn [0139] 17 contacting element [0140] 18 terminal pole [0141] 19 bush [0142] 20 inner mold [0143] 21 outer mold [0144] 22 potting space [0145] 23 directing body [0146] 24 grooved bar [0147] 24a bar [0148] 24b groove [0149] 25a-25d inner grooved bar [0150] 26a-26d outer grooved bar [0151] 27 perforated plate [0152] 27a plate [0153] 27b hole [0154] 28a-28d perforated plates [0155] 29 conical front end of the potted body [0156] 30 circumferential indentation [0157] 31 cable [0158] 31a sheath [0159] 31b core [0160] 32 potting compound [0161] 32a surface (potting compound) [0162] 32b side face (potting compound) [0163] 100 partially manufactured X-ray tube [0164] AA axial spacing [0165] AAG radial spacing of the anode and the cathode housing [0166] AEK axial extent of the ceramic body [0167] GRR largest radius of the recess [0168] KRR smallest radius of the recess [0169] R radius of the turn [0170] RA tube axis [0171] RK outer radius of the ceramic body on the rear side [0172] RAA radial spacing outward [0173] RAI radial spacing inward [0174] TR axial depth of the recess

LIST OF REFERENCES

[0175] [1] WO 2008/148426 A1 [0176] [2] DE 10 2017 217 181 B3 [0177] [3] U.S. Pat. No. 10,714,300 B2 [0178] [4] Company brochure “OEG-92J Industrial X-Ray tube”, Version 2021, of the Varex Imaging Corporation, Salt Lake City, Utah 84104, USA. [0179] [5] DE 10 2008 017 153 A1 [0180] [6] US 2012/0 076 278 A1 [0181] [7] JP 2015-232 944 A