X-ray tube with an insulating body enclosing a cast body

Description

[0001] The invention relates to an X-ray tube, which comprises a cathode housing with a radiation exit window, a cooled anode, a cathode, in particular a hot cathode, an insulating body for electrically isolating a high-voltage potential of the anode, an inlet line for coolant to the anode and an outlet line for coolant from the anode, and wherein in the insulating body the inlet line and the outlet line each comprise a plurality of turns.

[0002] Such an X-ray tube is known from WO 2008 / 148426 A1 (= reference [1]) and from DE 674415 C.

[0003] X-rays are used in a variety of ways in instrumental analysis and for producing images of human and animal patients in medicine. X-rays are typically generated in an X-ray tube by the emission of electrons from an electrically heated cathode. These electrons are accelerated in a vacuum by an electric field toward an anode, where bremsstrahlung and characteristic X-rays are released, depending on the anode's target material (e.g., tungsten, molybdenum, or rhodium).

[0004] When generating X-rays, only a small portion, usually approximately 1%, of the applied energy is converted into X-ray power. The remaining portion of the applied energy generates heat. To prevent the anode from melting, it is therefore common practice to cool the anode. The anode is usually cooled using a coolant that flows through the anode. The coolant is channeled through cooling channels within the anode.

[0005] During operation, the anode is typically at high voltage potential. As a result, electrical insulation of the anode is necessary. The anode can be arranged on an electrically insulating insulating body. Coolant lines that supply the anode with coolant typically run through the insulating body. Since the coolant in the anode is also at high voltage, care must be taken to prevent voltage breakdowns across the coolant column. For this, the length of the coolant column, the conductivity or dielectric strength of the coolant, and the applied voltage must be selected appropriately. Only coolants with low electrical conductivity, such as demineralized water (DI water), are regularly used as coolants.

[0006] The reference [1] cited at the beginning shows a high-voltage X-ray tube comprising a cathode and an anode, as well as an anode insulation element. The anode insulation element is designed as a ceramic cone and includes an opening for a high-voltage connector. An intermediate element is inserted between the anode insulation element and a high-voltage connector inserted into the opening for the high-voltage connector. An inflow channel and an outflow channel run through the intermediate element, through which a cooling fluid, in particular a cooling oil, is conducted to the anode. The inflow and outflow channels can be spiral-shaped. Drilling and casting are proposed for the production of conduction structures.

[0007] If the inlet and outlet channels are designed spirally, a longer insulation distance can be provided in the coolant. However, spiral-shaped piping structures within the intermediate body are difficult to manufacture. Reference [1] does not provide any further details on how spiral-shaped inlet and outlet lines should be manufactured, particularly in the intermediate body.

[0008] Imprecise placement of the supply line and the drain line in an insulation body, in particular too small a distance between turns to each other or to an inner or outer wall of the insulation body, can lead to voltage flashovers and damage to the X-ray tube.

[0009] A vertical anode for an X-ray tube is known from DE 10 2017 217 181 B3 (= reference [2]) and US 10,714,300 B2 (= reference [3]). The vertical anode comprises a base anode body. The base anode body contains spiral-shaped cooling sections through which a cooling fluid flows to cool the anode.

[0010] The spiral-shaped cooling sections allow for better cooling of the anode body. However, there is no further discussion of what an insulating body for electrically insulating the anode body might look like, nor of how an inflow and outflow channel for the cooling fluid might be designed.

[0011] Another X-ray tube is the OEG 9X series of X-ray tubes from Varex Imaging Corporation, Salt Lake City, UT 84104, USA (formerly Varian Medical Systems), see the company brochure "OEG-92J Industrial X-Ray tube", version 2021 (=reference [4]). An X-ray tube in this series essentially comprises an anode at high-voltage potential, which is attached to a ring-shaped glass element with a double U-shaped cross-section. An oil-filled hollow body is attached to the underside of the glass element, facing away from the anode. A coolant line runs in the oil-filled hollow body from a rear part of the X-ray tube through the glass element to the anode and back into the rear part of the X-ray tube. The coolant line runs in the rear part of the X-ray tube with coils around a high-voltage connection. The coils are axially adjacent to one another and radially outwardly against a plastic wall.

[0012] The coils retain a certain degree of mobility in the oil, which can promote voltage breakdowns. The adjacent coils also have a relatively low dielectric strength. A comparatively long coolant line is required to prevent voltage breakdowns, and this design accordingly has a relatively long length. Furthermore, even a small leak in the hollow body of the X-ray tube can cause oil to leak out and contaminate the rest of the X-ray tube and the surrounding area. This oil contamination is often difficult to remove.

[0013] A cooled radiation generator is known from DE 10 2008 017 153 A1 (=reference [5]). The radiation generator comprises a tube-shaped protective housing filled with a cooling liquid. A radiation-generating tube with a cathode and an anode is arranged inside the tube-shaped protective housing filled with the cooling liquid. A flow channel filled with a cooling medium is formed on the tube-shaped protective housing. The flow channel can be used to cool the interior of the tube-shaped protective housing. The cooling medium is fed into and out of the flow channel via an inlet and outlet line.

[0014] A cooled X-ray tube is known from US 2012 / 0 076 278 A1 (=reference [6]). The X-ray tube comprises a housing, a cathode assembly mounted on the housing with a cathode, a stator assembly mounted on the housing with a rotating anode, and an X-ray window mounted on a window frame on the housing. Liquid cooling channels are formed in the housing and in the stator assembly. Coolant can be fed into and out of the liquid cooling channels via connections on the housing and the stator assembly. The coolant can be used to cool the housing and the stator assembly.

[0015] JP 2015-232 944 A (=reference [7]) discloses an X-ray tube device that can prevent damage to a vacuum envelope of the X-ray tube device. The X-ray tube device comprises an X-ray tube, a stress relaxation film, and a molded part. The X-ray tube has a cathode, an anode, and the vacuum envelope. The film is bonded to the outer surface of the vacuum envelope. The molded part completely covers the vacuum envelope and the film and is bonded to them. The stress relaxation film can reduce the stress applied from the outside of the vacuum envelope. Object of the invention

[0016] It is the object of the present invention to present an easy-to-manufacture X-ray tube with which a high electrical breakdown strength and a compact design can be achieved. Description of the invention

[0017] This object is achieved according to the invention by an X-ray tube of the type mentioned at the outset, which is characterized in that that the insulation body comprises a ceramic body and a cast body, wherein the anode and the cathode housing are attached to the ceramic body, and the cast body is attached to the ceramic body, that the cast body comprises an inner casting mold and, at least temporarily during the manufacture of the X-ray tube, an outer casting mold, that in a casting space between the outer casting mold and the inner casting mold, the inlet line and the outlet line are each formed with a hose that forms the plurality of turns, that in the casting space at least one plastic aligning body is arranged, with which the hoses are aligned in the casting space so that the turns of the hoses are spaced from the outer casting mold and the inner casting mold, and that the casting space is filled with a plastic casting material in a cured state,so that the 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 straightening body and / or the plastic of the casting material.

[0018] The present invention proposes the use of at least one plastic guide body to arrange the hoses with the multiple coils in the casting chamber. The at least one guide body enables a defined and precise arrangement of the hoses in the casting chamber, particularly during the pouring of the casting material and until the casting material has hardened; thereafter, the defined and precise arrangement is maintained.

[0019] The guide body (auxiliary body) guides and stabilizes the hoses in the casting chamber. With at least one guide body, the hoses can be safely and easily positioned so that they do not directly touch either the inner or outer mold. This prevents arcing from the hoses or the coolant they contain onto the inner and outer mold (or the outside of the filled casting chamber) during operation of the X-ray tube, thus preventing damage to the X-ray tube.

[0020] The straightening bodies also enable a defined, for example uniform, arrangement of the hoses, in particular in the radial direction and / or axial direction.

[0021] Because the hoses can be precisely positioned in the cast body, meaning the positioning tolerances are small, only these small positioning tolerances need to be taken into account when designing the X-ray tube with regard to the high voltage (and associated dielectric strength) desired during operation. In particular, the straightening bodies can be used to ensure a minimum spacing between hose sections. In other words, less safety margin is required when spacing the hoses from the inner and outer casting mold, or preferably between the turns of the hoses themselves. This reduces the space required for the multiple-winding hoses, allowing the X-ray tube to be built even more compactly, particularly in the radial and / or axial directions, depending on the design.

[0022] The inlet line and the outlet line generally each run essentially helically (helically) around a tube axis of the X-ray tube, forming a double helix structure (i.e., the individual turns can be alternately assigned to the inlet line and the outlet line); the double helix can be cylindrical (straight) or conical (tapering). Preferably, the inlet line and the outlet line run in a similar (symmetrical) manner around the tube axis, in particular with the same (local) pitch and the same (local) radius, with the inlet line and the outlet line being arranged rotated by 180° relative to each other around the tube axis.

[0023] The plastic casting material is poured into the casting chamber in its liquid state. For this purpose, the X-ray tube can be positioned, for example, with the anode facing the support surface; an opening leading into the casting chamber points upwards in the opposite direction. The liquid casting material can be distributed evenly within the casting chamber (between the inner mold and the outer mold) without forming gaps or cavities. The casting material can also be distributed particularly well between the tubes, which are held in position by at least one straightening element.

[0024] The casting material is then cured, which, depending on the material system, can be achieved, for example, by waiting and / or heat treatment, and retains its shape in the cured state. If desired, the outer casting mold can be removed from the rest of the casting body (in particular from the cured casting material of the filled casting space) while the casting material is cured. In the cured state, the plastic casting material - optionally together with the plastic material of at least one straightening body - permanently separates the tubes from the walls of the inner casting mold and the outer casting mold (or the outside of the filled casting space) and preferably also separates the tubes from each other, so that contact between the tubes and the walls, and preferably also between each other, is no longer possible.This minimizes the risk of flashover between the tubes and the walls during operation of the X-ray tube. Casting material between the tubes can also help minimize the risk of voltage flashovers between the tubes or adjacent coils, potentially reducing the thickness of the tube walls or making the dielectric strength of the tube material less relevant. Furthermore, the ceramic body can be tightly bonded to the cast body without gaps or cavities. Typically, the casting is already firmly mechanically attached to the ceramic body by casting the cast body onto the ceramic body.

[0025] As a plastic, the cast material exhibits good dielectric strength, which prevents arcing and thus damage to the X-ray tube components in a compact design. Using the cast material eliminates the need for an oil-filled hollow body containing electrically insulating oil through which the tubes are routed. The cured cast material may still be flexible ("soft") to a certain extent, but is no longer flowable and, in particular, no longer liquid.

[0026] The anode can be easily attached to the ceramic body in a vacuum-tight manner, for example, by soldering it to a metallized surface of the ceramic body or by temperature- and vacuum-resistant bonding to the ceramic body. The design of the ceramic body also allows for adjustment of the creepage distance on both the side of the ceramic body facing the anode and the side of the ceramic body facing the cast body, thereby improving the dielectric strength. The ceramic body can be made of Al2O3 or ZrO2, for example.

[0027] The hoses have a certain degree of bendability or flexibility, particularly for laying in the casting chamber, with the at least one straightening body being used to align the hoses in the casting chamber. The hoses preferably have a minimum degree of inherent rigidity, which gives each hose a basic geometry that is adapted to the desired hose geometry in the X-ray tube. Furthermore, the inner walls of the hoses can be designed such that they have a low level of roughness and thus offer little flow resistance to the coolant flowing through the hoses. This allows for efficient inflow and outflow of coolant to the anode. The inner walls of the hose can also be additionally coated for this purpose, in particular to adjust the surface tension between the coolant and the hose.

[0028] It's usually easy to make the hoses liquid-tight. This prevents fluid leaks in the insulation body, which could, for example, lead to unwanted arcing in the insulation body and thus damage the components of the X-ray tube.

[0029] Deionized water (DI water), single-distilled water, or multiply distilled water can be used as a coolant, for example. Water-based coolants are preferred due to their high specific heat capacity; however, other coolants, such as oil, particularly silicone oil, can also be used in addition to water-based coolants. The coolant preferably has a low electrical conductivity of less than 1 µS / cm. Since the length of the required coolant column and thus the length of the coolant-filled hoses depend, among other things, on the conductivity of the cooling medium, the length of the hoses and thus the space required for the X-ray tube can be reduced by selecting a coolant with a low conductivity.

[0030] The X-ray tube according to the invention is typically connected with the cathode to ground (irrespective of the cathode's heating current) and the anode to a (positive) high-voltage potential. Within the scope of the invention, it is also possible to connect the cathode to a (negative) high-voltage potential, if desired. Preferred embodiments of the invention

[0031] In a preferred embodiment of the X-ray tube according to the invention, it is provided that the hoses are further aligned in the casting chamber with the at least one straightening body, so that the turns of the hoses are also spaced from one another, and that the casting chamber is further filled with the casting material, so that the spaces between the turns are also occupied by the plastic of the at least one straightening body and / or the plastic of the casting material. By means of the at least one straightening body, the turns of the hoses can be reliably and precisely spaced from one another in the casting chamber, in particular with regard to the axial direction. The distance between the turns of the hoses can be set so precisely that, during operation of the X-ray tube at a given high voltage, no arcing occurs between the turns of the hoses or the coolant contained therein, which could therefore damage the X-ray tube.Precise alignment allows for efficient use of the space in the X-ray tube and its insulation body, thus minimizing the space required for the tubes. This allows the X-ray tube to be designed even more compactly. The tubes can be securely held in position and spaced apart from each other by the casting material while the mold is being filled with the straightening elements. When the mold is filled with the casting material in its liquid state, the casting material can be distributed evenly between the coils without creating gaps or cavities.

[0032] A further preferred embodiment is characterized in that the ceramic body has a circumferential recess between the cathode housing and the anode on a front side facing the anode, and in that the ceramic body has a central recess on a rear side of the ceramic body facing the cast body. The circumferential recess extends the path between the anode and the cathode housing (which is grounded) on the front side of the ceramic body, thereby establishing a long creepage distance. The central recess extends the path between structures connected to the anode that lead through the ceramic body (typically a high-voltage feedthrough and usually also tubes for the coolant) and the outside of the insulating body (which is usually grounded) on the rear side of the ceramic body, thereby establishing a long creepage distance between the ceramic body and the cast body.In longitudinal section, the ceramic body can then be approximately W-shaped; due to the multiple recesses, the ceramic body is then also referred to as crown-shaped. The circumferential recess is typically V-shaped or U-shaped (on each side in longitudinal section), and the central recess is also typically (inverted) V-shaped or U-shaped in longitudinal section along the tube axis. Note that in some embodiments, only the central recess is provided, and in other embodiments, both the circumferential recess and the central recess are provided.

[0033] In a preferred development of this embodiment, the tubes are partially arranged in a region of the central recess of the ceramic body, in particular wherein at least half a turn of the tubes and / or at least 10% of the length of the tubes is arranged in the central recess of the ceramic body. This allows the space of the recess to be used efficiently and the tubes to be connected closer to the anode (for example, to tubes / pipe sockets that protrude through the ceramic body), thus extending the length of the tubes and thus the path for the high voltage to drop from the anode. The recess typically extends in the direction of the tube axis over at least 50% of the axial extent of the ceramic body.The recess may be conically shaped, preferably with the widest radius of the recess on the rear side of the ceramic body extending over at least 2 / 3 of the outer radius of the ceramic body on its rear side.

[0034] A further preferred embodiment is one in which the inner mold is designed as a socket for a high-voltage plug for connection to the anode. The socket and the high-voltage plug allow the anode to be connected to the high voltage in a simple, particularly reversible manner. The socket, which is made of electrically insulating material (usually a plastic), can provide the necessary creepage distance to prevent arcing caused by the applied high voltage from a connection pole (usually at the base of the socket) to the grounded parts of the X-ray tube (such as the coolant connections) or the cable shield. In addition, the socket can protect the high-voltage connection of the high-voltage plug (which, when connected, projects into the socket and contacts the connection pole) from accidental contact.The bushing is typically located radially centrally in the cast body on the side of the insulation body facing away from the anode, and preferably the inlet line and the outlet line also run around the bushing, whereby a particularly compact and electrostatically stable coaxial structure of the high-voltage potentials can be achieved.

[0035] An alternative embodiment is also preferred, characterized in that the inner casting mold is designed as a cable comprising an insulating sheath and a core extending within the sheath, to which the anode is connected. This embodiment is particularly cost-effective and can achieve an even more compact structure, especially in the radial direction. The cable can be cast directly with the casting material.

[0036] A particularly preferred embodiment is one in which the at least one straightening body and the casting material are made of the same plastic. Using the same plastic for the straightening body(s) and the casting material results in a particularly good bond between the straightening body and the casting material. This results in a largely monolithic casting with defined internal hoses for the coolant. Distortions of field lines at the interface between the straightening body and the casting material are minimized, as are leakage currents at these interfaces. The structure of the casting body is therefore far less susceptible to voltage breakdowns. Using the same plastic for the straightening body(s) and the casting material allows the structure of the X-ray tube to be made even more compact due to the improved dielectric strength.

[0037] In a preferred refinement of this embodiment, the plastic of the casting material comprises a silicone, an epoxy resin, or a polyurethane. These plastics have proven particularly effective in practice. The plastics are inexpensive to purchase, can be easily cast in the liquid state, are curable, and exhibit good electrical insulation properties. Furthermore, these materials are subject to minimal aging effects (especially compared to insulating oil).

[0038] In a particularly preferred embodiment, it is provided that several straightening bodies are arranged in the casting chamber, in particular wherein the straightening bodies are each clamped between the inner casting mold and the outer casting mold and / or between the hoses on the one hand and the inner casting mold or the outer casting mold on the other. By using multiple straightening bodies, the hoses can be aligned even better in the casting chamber and can be held in position particularly easily. By clamping the straightening bodies to the hoses and the casting molds, a secure hold of the straightening bodies is easily possible, especially for the casting process. Alternatively, it is also possible for the straightening bodies to be clamped against one another and at least against the outer casting mold. Generally, the straightening bodies rest against the hoses in order to keep them aligned (during the casting process).

[0039] An advantageous development of this embodiment is one in which the alignment bodies are arranged at angular positions in a respective sectional plane perpendicular to a tube axis of the X-ray tube, wherein the angular positions form a rotationally symmetrical arrangement with respect to the tube axis. Due to the rotationally symmetrical arrangement of the alignment bodies, they can act evenly on the tubes from multiple directions, so that the tubes are subjected to approximately uniform radial force (clamping force) over the circumference of their coils and / or are radially aligned. This minimizes the roundness of the coils, and the tubes are supported particularly stably by the alignment bodies.

[0040] A further development of this refinement is also advantageous, characterized by N straightening elements supporting the hoses toward the inner casting, and N straightening elements supporting the hoses toward the outer casting. The rotationally symmetrical arrangement of the angular positions has an N-fold number, where N is a natural number with N≥2. This distribution of straightening elements has proven particularly effective in practice. This allows the hoses to be positioned very precisely and securely in place in the casting chamber.

[0041] It is also advantageous if the N straightening bodies that support the hoses towards the inner casting body and the N straightening bodies that support the hoses towards the outer casting body are arranged in a respective sectional plane with respect to the tube axis at identical angular positions, or at angular positions offset by 360° / (2*N) from one another. The positioning of the straightening bodies at identical angular positions enables particularly easy clamping of each hose section between the opposing straightening bodies; this also allows for very precise alignment of the hoses, in particular with minimized compression of the coils. In some embodiments, with identical angular positions of the straightening bodies, it can also be provided that the straightening bodies support one another. By positioning the straightening bodies at different angular positions, the hoses can be aligned in the circumferential direction at a particularly large number of points, whereby the alignment of the hoses, in particular in the axial direction, can be designed with particular precision.It should be noted that the N straightening bodies that support the hoses towards the inner casting and the N straightening bodies that support the hoses towards the outer casting can be designed as a single piece (e.g. as a perforated plate) or as multiple pieces (e.g. as opposing grooved bars) when arranged at identical angular positions.

[0042] Also preferred is an embodiment in which one or more straightening bodies of the at least one straightening body are designed as a perforated plate, comprising a plate and a plurality of holes in the plate through which the hoses are guided, in particular wherein a respective perforated plate is clamped between the inner casting mold and the outer casting mold. Such perforated plates are simple to manufacture and easy to position in the casting mold. The hoses are guided through the holes in the perforated plate (typically before the perforated plate and the hoses are arranged between the outer casting mold and the inner casting mold). A uniform arrangement of the hoses is easily possible due to the predetermined structure of the perforated plate. The distance between the hoses can be adjusted via the distances between the individual holes.Likewise, the distance of the hoses to the inner and outer mold can be adjusted via the distance of the holes to the side edges of the perforated plate when the side edges are in contact with the inner and outer mold when clamped.

[0043] A further embodiment is advantageous, which is characterized in that one or more straightening bodies of the at least one straightening body are designed as a grooved bar, comprising a bar and several grooves, in particular semicircular grooves, into which the hoses are inserted, in particular wherein a respective grooved bar is clamped between the hoses on the one hand and the inner casting mold or the outer casting mold on the other. Such grooved bars are particularly easy to manufacture. The grooved bars can be arranged simply and flexibly on the inner casting mold and / or the outer casting mold. The hoses are inserted into the grooves of the grooved bars and thereby aligned. By clamping the grooved bars between the hoses and one of the casting molds, the grooved bars can be easily fixed for the casting process.

[0044] In an advantageous further development of this embodiment, grooved bars that support hoses toward the inner casting body and grooved bars that support hoses toward the outer casting body are arranged in pairs opposite each other. This allows the hoses to be easily held precisely in position, particularly with the hoses being clamped between the opposing grooved bars. With appropriately sized grooved bars, the grooved bars can also support each other.

[0045] Equally advantageous is an embodiment in which the coils of the tubes are wound around a tube axis and arranged along the tube axis. This allows for easy arrangement of the tubes. The coils of the tubes can be arranged in a space-saving manner.

[0046] A further development of this embodiment is also advantageous, in which the windings have a constant radius with respect to the tube axis, in particular, wherein the outer casting mold and the inner casting mold are essentially cylindrical and coaxial with the tube axis, so that the windings have a constant radial distance from the outer casting mold and, furthermore, the windings have a constant radial distance from the inner casting mold. This can be implemented particularly easily and precisely in practice.

[0047] A particularly advantageous development of this design is one in which the coils are spaced at a constant distance from one another in the axial direction. This, too, can be easily and precisely implemented in practice. The constant (even) spacing of the coils of the hoses, combined with a constant coil radius, distributes the voltage drop across the length of the coolant column evenly across all coils; the potential difference between adjacent coils (at the same angular positions) is the same for all coils. This allows for optimal space utilization in the cast body while maintaining the desired dielectric strength between the coils of the hoses.

[0048] Also advantageous is an alternative development of the above embodiment in which the turns have a radius with respect to the tube axis that increases away from the anode, in particular wherein the outer casting mold and the inner casting mold are essentially cylindrical and coaxial with the tube axis, so that the turns have a radial distance from the outer casting mold that decreases away from the anode and, furthermore, the turns have a radial distance from the inner casting mold that increases away from the anode. In the hose sections that are close to the anode with respect to the coolant path, a comparatively high potential still prevails. Because the radius of the turns is still small near the anode, a greater radial distance from the outer casting mold (which typically has contact with ground) is maintained, so that better dielectric strength is achieved in this area.Conversely, in the tube sections that are far from the anode in terms of the coolant path, only a low potential (closer to ground) is present. The large radius of the coils far from the anode maintains a greater radial distance from the inner mold (in which a conductor carrying the high-voltage potential is located during operation), thus achieving better dielectric strength in this area as well. This allows for optimal use of the installation space in the X-ray tube.

[0049] A further development of this further development is also advantageous, which is characterized by the fact that the windings have a constant axial distance from one another or an axial distance from one another that increases away from the anode. A constant axial distance between the turns can be set up particularly easily. The dielectric strength can be improved even further by increasing the axial distance between the turns away from the anode and at the same time increasing the radius of the turns. As the radius of the turns increases away from the anode, the voltage drop across the coolant per turn away from the anode increases. This increases the potential difference between adjacent turns (at the same angular positions) away from the anode, which increases the risk of voltage flashovers. This can be (at least partially) compensated for in terms of dielectric strength by the axial distance increasing away from the anode.Preferably, the axial spacing of the windings is proportional to the radii of the windings; this achieves an approximately uniform voltage drop per axial distance (or a uniform field strength) in the cast body between the windings, as long as it is determined by the linear drop in the anode's high voltage over the length of the tubes in the coolant. The installation space in the X-ray tube is used optimally.

[0050] A preferred embodiment of the X-ray tube according to the invention is one in which the outer mold remains attached to the remaining cast body after the X-ray tube has been manufactured. In other words, the outer mold required during casting is not removed after casting, but remains part of the X-ray tube during operation. This is particularly simple. The outer mold can also mechanically stabilize the X-ray tube during operation. If necessary, the outer mold can be wrapped with a material that is highly electrically conductive and / or highly X-ray-absorbent, e.g., lead foil, to ensure grounding and radiation protection.

[0051] In an alternative embodiment, after the X-ray tube has been manufactured, the outer mold is removed from the remaining cast body. In other words, the mold required for casting is only attached to the ceramic body during the casting process and is no longer part of the X-ray tube during operation. This makes it possible to use one outer mold for the production of a multitude of X-ray tubes. If necessary, the remaining cast body can be wrapped with a material that is highly electrically conductive and / or highly X-ray-absorbent, e.g., lead foil, to ensure grounding and radiation protection.

[0052] Furthermore, within the scope of the present invention also falls a method for producing an X-ray tube described above, comprising the steps: a) To set up the casting chamber, the outer casting mold is arranged in a sealing manner on a rear side of the ceramic body facing away from the anode, and the inner casting mold is arranged in front of the rear side of the ceramic body, and in the casting chamber between the inner casting mold and the outer casting mold, the at least one plastic straightening body and the hoses are arranged, wherein the at least one straightening body aligns the hoses in the casting chamber such that the turns of the hoses are spaced apart from the outer casting mold and the inner casting mold, and preferably also the turns are spaced apart from one another, b) the casting chamber is filled with the plastic casting material in a liquid state, so that the spaces between the turns on the one hand and the outer casting mold and the inner casting mold on the other hand, and preferably also the spaces between the turns among themselves,are occupied by the plastic of the at least one guide body and / or the plastic of the casting material, c) the plastic casting material is cured. This manufacturing process allows for the simple manufacture of an X-ray tube with high dielectric strength and a compact design. The casting material can be easily and cleanly poured into the sealed casting chamber in its liquid state, and the casting material automatically and completely fills the provided casting chamber, in particular without gaps or cavities. The guide bodies and tubes are enclosed by the casting material, resulting in a solid casting that can provide good dielectric strength. The at least one guide body allows the tubes to be arranged particularly easily and precisely in the casting chamber, whereby desired distances to the inner and outer casting molds can be adjusted.In particular, with tight tolerances. Furthermore, the hoses can be arranged with the desired spacing of the coils from one another, in particular with tight tolerances, by means of the at least one straightening element. The at least one straightening element holds the hoses stable and in position while the casting chamber is being filled with the casting material in the liquid state. After the casting material has hardened, the hoses remain in the desired, precisely adjusted positions, still being held by the straightening elements and now also by the hardened casting material.

[0053] The individual steps of step a) can generally take place in any order. Typically, during step a), at least one straightening element is mechanically clamped to the tubes attached to the straightening element, typically between the inner and outer molds (especially in the case of a perforated plate), or between the tubes on the one hand and the inner or outer mold on the other (especially in the case of slotted bars).

[0054] To achieve a better bond between the straightening body and the casting material, the plastic of the straightening body and the plastic of the casting material can be the same plastic. If the plastic of the (at least one) straightening body and the plastic of the casting material are the same plastic, the (at least one) straightening body is typically prefabricated and cured before being inserted into the casting chamber.

[0055] Note that at the beginning of step a), the tube head (in particular the cathode housing and the anode) has typically already been arranged on the ceramic body. Using the method according to the invention, an X-ray tube according to the invention, as described above, including the embodiments described above, can be manufactured.

[0056] In a preferred variant of the method according to the invention, it is provided that after step c), the outer casting mold remains on the remaining casting body. Accordingly, in this variant, an X-ray tube is produced in which the outer casting mold remains on the remaining casting body after the X-ray tube has been produced. This is particularly easy to implement; in particular, no demolding step for the outer casting mold is necessary after casting.

[0057] In another variant of the method according to the invention, the method further comprises a step d) the outer mold is removed from the rest of the cast body; according to this variant, an X-ray tube is manufactured in which, after the X-ray tube has been manufactured, the outer mold is removed from the rest of the cast body. The outer mold can then be used in the production of a large number of X-ray tubes; alternatively, however, the outer mold can also be used only once, if desired, especially if demolding requires the destruction of the outer mold.

[0058] Further advantages of the invention will become apparent from the description and the drawings. Likewise, the above-mentioned and further-described features can be used individually or in combination in any desired manner. The embodiments shown and described are not intended to be exhaustive, but rather are exemplary in nature for describing the invention. Detailed description of the invention and drawing

[0059] Fig. 1 shows a schematic longitudinal section of a first embodiment of an X-ray tube according to the invention, with slotted bars and tube turns of a uniform radius; Fig. 2 shows a schematic longitudinal section of a second embodiment of an X-ray tube according to the invention, with perforated plates and tube turns of a uniform radius; Fig. 3 shows a schematic longitudinal section of a third embodiment of an X-ray tube according to the invention, with slotted bars and tube turns of a variable radius and a crown-shaped ceramic body; Fig. 4 shows a schematic longitudinal section of a fourth embodiment of an X-ray tube according to the invention, with perforated plates and tube turns of a variable radius and variable axial spacing;Fig. 5 shows a schematic cross-section through an X-ray tube according to the invention, with straightening bodies at angular positions with a rotationally symmetrical arrangement of the angular positions, wherein two inner groove bars and two outer groove bars are opposite one another; Fig. 6 shows a schematic cross-section through an X-ray tube according to the invention, with straightening bodies at angular positions with a rotationally symmetrical arrangement of the angular positions, wherein four inner groove bars and four outer groove bars are opposite one another; . Fig. 7 shows a schematic cross-section through an X-ray tube according to the invention, with straightening bodies at angular positions with a rotationally symmetrical arrangement of the angular positions, wherein two inner groove bars are arranged offset by 90° to two outer groove bars; Fig. 8 shows a schematic cross-section through an X-ray tube according to the invention, with straightening bodies at angular positions with a rotationally symmetrical arrangement of the angular positions, wherein three perforated plates are arranged offset by 120° to each other; Fig. 9 shows a schematic longitudinal section of a partially manufactured X-ray tube, with cathode housing and ceramic body, which is manufactured according to the invention to form a complete X-ray tube; Fig. 10 shows the partially manufactured X-ray tube of Fig. 9 , with positioned inner and outer molds forming a casting chamber, with positioned straightening bodies and with positioned hoses; Fig. 11 shows the X-ray tube of Fig. 10, now completely manufactured, with the casting space filled with a casting compound; Fig. 12 shows the X-ray tube of Fig. 11 , after removing the outer mold.

[0060] The 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.

[0061] The X-ray tube 1 comprises a cathode housing 2, which is attached to a ceramic body 3 in a vacuum-tight manner, for example by soldering. Furthermore, an anode 4 (here with an approximately cylindrical anode body) is arranged within the cathode housing 2, which is also attached to the ceramic body 3 in a vacuum-tight manner, typically also by soldering. The cathode housing 2, the ceramic body 3, and the anode 4 define an evacuated space 5.

[0062] A cathode, here a hot cathode 6, is arranged in the evacuated space 5, typically formed with incandescent filaments. In the embodiment shown, the hot cathode 6 can be supplied with an electric current via a ground connection 7a and a power connection 7b, which are passed through the cathode housing 2 in a vacuum-tight manner. The electric current is typically an alternating current, preferably of low voltage, usually with a maximum voltage amplitude of 24 V or less. By means of this electric current (also called heating current), the hot cathode 6 can be heated, causing electrons to escape from the hot cathode 6.

[0063] During operation, the anode 4 is at a positive high-voltage potential (typically 20 kV to 60 kV, possibly higher in other applications) relative to the hot cathode 6. In the embodiment shown here, the hot cathode 6 is grounded during operation, regardless of the heating current already explained. Electrons emerging from the hot cathode 6 are accelerated by the high voltage, under the influence of a grounded shield 8, from the hot cathode 6 to the anode 4, here onto a top side 4a of the anode 4. Upon impact with the anode 4, the electrons are decelerated, generating X-rays in the form of bremsstrahlung. In addition, electrons are knocked out of the inner shells of the atoms of the material ("target") arranged on the top side 4a of the anode 4. When electrons from the outer shells fill the inner shells of these atoms, X-rays are emitted in the form of characteristic X-rays.Typically, a desired material is attached to the top side 4a of the anode 4 to generate the X-ray radiation characteristic of that material. The generated X-ray radiation exits 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 of a sample or for taking an X-ray image.

[0064] The electrons accelerated toward the anode 4 heat the metal anode 4. To prevent the anode 4 from melting, the anode 4 is cooled with a coolant. Formed within the X-ray tube 1 is an inlet line 9 that carries the coolant to the anode 4, and a drain line 10 that carries the coolant away from the anode 4. Note that the inlet line 9 and the return line 10 can also be connected to the coolant flow in reverse, if desired.

[0065] Anode 4, which is at high-voltage potential, must be electrically insulated. In particular, voltage breakdowns to the exterior of X-ray tube 1 and other grounded structures must be prevented.

[0066] The electrical insulation of the anode 4 on the X-ray tube 1 is achieved essentially by an insulating body 11 and the evacuated space 5 provided in the cathode housing 2. According to the invention, this insulating body 11 comprises the ceramic body 3 made of ceramic material, on which the anode 4 and the cathode housing 2 sit, and a cast body 12 which is fastened to the back of the ceramic body 3. The ceramic body 3 consists of a vacuum-tight, ceramic material, for example Al 2 O 3 . The cast body 12 consists essentially of a cast material 32 made of plastic. The plastic of the cast material 32 can be silicone, for example. The inlet line 9 and the outlet line 10 are guided through the insulating body 11 to the anode 4.The insulation body 11 (and correspondingly also the respective section of the ceramic body 3 and cast body 12) is approximately circular-cylindrical on the outside and aligned along the tube axis RA.

[0067] It should be noted that the coolant in the anode 4 is in contact with the high-voltage potential and is grounded in the area of ​​the coolant connections 9b, 10b. Accordingly, the high voltage drops in the coolant over the length of the inlet line 9 and over the length of the outlet line 10. To prevent breakdown of the high voltage, a coolant with low electrical conductivity or high dielectric strength is used, e.g., deionized water or silicone oil. Second, the X-ray tube 1 is designed to allow a large length (path length) of the inlet line 9 and the outlet line 10 in a compact space, and furthermore ensures sufficient spacing of structures at different electrical potentials.

[0068] In the design shown, two tubes 14a, 14b, typically made of metal, lead through the ceramic body 3. Anode channels 4b for the coolant are connected at the upper ends and extend within the anode 4, and hoses 9a, 10a are connected at the lower ends. It should be noted that in other designs, the coolant passage through the ceramic body 3 can also be designed differently, for example, with coaxial tubes or ceramic tubes or simple holes into which plug-in connectors protrude (not shown). The hoses 9a, 10a form the inlet line 9 and the outlet line 10, insofar as they extend within the cast body 12. The hoses 9a, 10a are made of a plastic material. In the cast body 12, the tubes 9a, 9b each form several turns 16 in a central part, which are arranged one behind the other in the axial direction and form a double helix in this area (more on this below).

[0069] The ceramic body 3 forms a central recess 15 on its rear side facing away from the anode 4, which recess is conical in this case. In the axial direction (along the tube axis RA), the recess 15 extends over a depth TR into the ceramic body 3, which has an overall axial extent AEK. In the embodiment shown, approximately TR=0.8*AEK applies; generally preferred is TR≥0.5*AEK or else TR≥0.75*AEK. In the radial direction (perpendicular to the tube axis RA), the recess 15 extends at its widest point on the rear side of the ceramic body 3 with a largest radius GRR, and at its narrowest point near the anode with a smallest radius KRR. The ceramic body 3 has an outer radius RK in the region of its rear side; note that the ceramic body 3 has a uniform outer radius in the embodiment shown. In the embodiment shown, approximatelyGRR=0.75*RK; generally preferred is GRR≥0.5*RK or GRR≥0.67*RK. Furthermore, in the embodiment shown, approximately KRR=0.53*RK applies; generally preferred is KRR≥0.33*RK or KRR≥0.40*RK.

[0070] The recess 15 in the ceramic body 3 allows the tubes 9a, 10a to move axially close to the anode 4, and the depth TR of the recess 15 can be used, at least in part, to allow the high voltage to drop across the coolant in the tubes 9a, 10a. The tubes 14a, 14b, which connect the anode channels 4b to the tubes 9a, 10a, can be comparatively short. A considerable length of tubing, usually at least 10% of the respective total tubing length or even a tubing length corresponding to at least half a coil 16 (i.e., at least R*Pi, where R is the radius of the coils 16), can be accommodated in the area of ​​the recess 15. The recess 15 also causes a comparatively long creepage distance from the tubes 14a, 14b to the radial outer side of the ceramic body 3 along the interface to the cast body 12, in particular much longer than the radius RK of the ceramic body 3.

[0071] A metal contact element 17 also extends through the ceramic body 3, connecting the anode 4 to a terminal 18. The contact element 17 extends centrally within the X-ray tube 1 through the cast body 12 and, in the embodiment shown, leads into a socket 19 for a high-voltage plug (not shown), which can be used to connect the high voltage for the anode 4 to the terminal 18 in the socket 19. The socket is made of an electrically insulating material, such as a plastic.

[0072] The bushing 19 simultaneously forms an inner casting mold 20 for the cast body 12. The bushing 19 is approximately cylindrical and aligned with the tube axis RA.

[0073] The cast body 12 further comprises an outer casting mold 21, which here is designed as a cylindrical tube that can be made of metal or plastic, for example. The inner casting mold 20, the outer casting mold 21, and the ceramic body 3 define a casting chamber 22. The hoses 9a, 10a, in particular, run within this casting chamber 22.

[0074] The hoses 9a, 10a are aligned in the casting chamber 22 using alignment elements 23. The alignment elements 23 are made of plastic. Typically, the alignment elements 23 are clamped in the casting chamber 22. In the embodiment shown, the alignment elements 23 are designed as grooved bars 24. The grooved bars 24 each comprise a bar 24a on which several grooves 24b, here semicircular grooves, are formed. A turn 16 of a hose 9a, 10a is inserted into each groove 24b. In the embodiment shown, radially inner grooved bars 25a, 25b and radially outer grooved bars 26a, 26b are located opposite each other, between which the turns 16 of the hoses 9a, 10a are clamped. The groove bars 24 are clamped accordingly between one of the casting molds 20, 21 and the hoses 9a, 10a.

[0075] The alignment bodies 23 align the coils 16 of the hoses 9a, 10a with high precision. The spacing of the individual coils 16 is adjusted radially inward toward the bushing 19 / inner mold 20 (RAI), radially outward toward the outer mold 21 (RAA), and axially relative to one another (AA). In the embodiment shown, this ensures that the adjacent coils 16 of the various hoses 9a, 10a, and furthermore, the hoses 9a, 10a and the inner mold 20, and finally the hoses 9a, 10a and the outer mold 21, do not touch each other (i.e., AA>0, RAI>0, RAI>0). In the embodiment shown, for all turns 16, the radial distance RAI inwards to the inner casting mold 20 is the same, furthermore the radial distance RAA outwards to the outer casting mold 21 is the same, and furthermore the radius R of the turns 16 with respect to the X-ray axis RA is the same.In addition, the axial distance AA between all windings 16 is the same.

[0076] The casting chamber 22 was filled with a liquid plastic casting material 32, so that the entire casting chamber 22 not occupied by other structures (hoses 9a, 10a, straightening element 23, contacting element 17) was filled with the casting material 32. The straightening elements 23 ensured that the hoses 9a, 10a could not shift during casting and the subsequent curing of the casting material 32, and in particular that the specified distances relevant to the dielectric strength (e.g., RAI, RAA, AA for the respective windings 16) were maintained with high precision. The plastic of the casting material 32 and the plastic of the straightening elements 23 were selected to be the same, in particular, a silicone material.This minimizes leakage currents at the interfaces between the straightening bodies 23 and the casting material 32; this interface (as far as the electrical properties are concerned) essentially disappears after the casting material 32 has hardened.

[0077] The cast body 12 engages with a conical front end 29 in the recess 15 of the ceramic body 3 and is secured thereto. The X-ray tube 1 can achieve good vacuum tightness and high-voltage resistance with the ceramic body 3, and good watertightness and high-voltage resistance with the cast body 12 in a compact space. The cast material 32 is easy to handle and maintain (in particular, the cured cast material 32 can no longer leak from the casting chamber 22 and exhibits little thermal expansion and aging, unlike insulating oil). A long coolant column (path length of the inlet and outlet lines) can be established, particularly by utilizing the installation space axially and radially within the ceramic body 3.The hoses 9a, 10a can therefore exhibit a certain degree of flexibility, yet can still be defined and positioned at the required spacing within the cast body 12 thanks to the guide elements 23. Creepage distances can easily be created with a large length (e.g., between the cast body 12 and the ceramic body 3) or completely avoided (by using the same plastic for the guide elements 23 and the cast material 32). Overall, a simple and compact design of the X-ray tube 1 is possible, reliably preventing voltage breakdowns and ensuring a defined and safe coolant flow.

[0078] It should be noted that in the case of the X-ray tube 1, the outer casting mold 21 can also be removed (after the casting material has been poured and hardened) (not shown in detail in Fig. 1 , cf. but Fig. 12 rear).

[0079] In the Figures 2 to 4Further embodiments of an X-ray tube 1 according to the invention are explained, which largely correspond to the embodiment of Fig. 1 Only the essential differences to the design of Fig. 1 explained.

[0080] The Fig. 2 shows a second embodiment of an X-ray tube 1 according to the invention.

[0081] In this X-ray tube 1, the alignment bodies 23 for the tubes 9a, 10a are designed as perforated plates 27. The perforated plates 27 are each formed by a plate 27a containing a plurality of holes 27b. The coils 16 of the tubes 9a, 10a are guided through the holes 27b. The perforated plates 27 are typically clamped between the inner mold 20 and the outer mold 21, particularly during the casting and curing of the casting material. Alternatively, the perforated plates 27 can also be aligned with respect to the rest of the X-ray tube 1 using an external holder during the casting and curing process.

[0082] The Fig. 3 shows a third embodiment of an X-ray tube 1 according to the invention.

[0083] In this embodiment, the ceramic body 3 is formed with a circumferential recess 30 on its front side facing the anode 4. This recess 30 lies radially between the anode 4 and the cathode housing 2.

[0084] As a result, a creepage distance from the anode 4 to the outside of the ceramic body 3 at the interface between the ceramic body 3 and the evacuated space 5 is extended, in particular significantly longer than the distance AAG between the anode 4 and the cathode housing 2. The circumferential recess 30 appears approximately V-shaped in longitudinal section on each side of the tube axis RA (also U-shaped in other embodiments, not shown). In longitudinal section, the ceramic body 3 as a whole appears approximately W-shaped, or in three dimensions also approximately crown-shaped.

[0085] In the embodiment shown, a cable 31 serves as the inner casting mold 20. The cable 31 is formed with an insulating plastic sheath 31a and a metal core 31b. The core 31b is connected to the contacting element 17, so that high voltage can be applied to the anode 4 via the core 31b. The insulating sheath 31a extends in the axial direction (along the tube axis RA) beyond the windings 16 into the casting body 12. The sheath 31a is formed with a constant diameter, and the cable 31 is aligned along the tube axis RA. When the casting chamber 22 is cast, the cable 31 is permanently encapsulated in the X-ray tube 1.

[0086] Furthermore, in this embodiment, corresponding straightening bodies 23 ensure that the radial distance RAA decreases towards the outside of the turns 16 of the hoses 9a, 10a to the outer casting mold 21 away from the anode 4. Conversely, the radial distance RAI increases towards the inside of the turns 16 of the hoses 9a, 10a to the inner casting mold 20 away from the anode 4. In the inlet line 9 and in the outlet line 10, the (local) potential is higher the closer a respective line section (along the line path of the inlet line 9 or the outlet line 10) is to the anode 4. Therefore, with this embodiment, the radial distance of line sections with high potential from the outer casting mold 21 (in contact with the ground) is greater than for line sections with low potential.Conversely, the radial distance between low-potential conductor sections and the (high-voltage) core 31b is also greater than that between high-potential conductor sections. This prevents voltage breakdowns and allows for a particularly compact design of the X-ray tube 1 at a given high voltage.

[0087] In this design, the straightening bodies 23 are formed as wedge-shaped slot bars 24, and the windings 16 have an equal axial distance AA from one another.

[0088] The Fig. 4 shows a fourth embodiment of an X-ray tube 1 according to the invention.

[0089] In this embodiment, the straightening bodies 23 are again designed such that the radial distance RAA decreases towards the outside of the turns 16 of the tubes 9a, 10a to the outer casting mold 21 away from the anode 4. Conversely, the radial distance RAI increases towards the inside of the turns 16 of the tubes 9a, 10a to the inner casting mold 20 away from the anode 4. In addition, it is provided here that the axial distance AA increases from adjacent turns 16 away from the anode 4. Due to the increase in the radii R of the respective turns 16 in the axial direction away from the anode 4, a higher voltage drop per turn 16 occurs for turns 16 that are further away from the anode 4 than for turns 16 that are closer to the anode 4. Due to the larger axial distances AA between the windings 16, which are located further away from the anode 4, voltage breakdowns between axially adjacent windings 16 can be prevented and a more compact construction of the X-ray tube 1 can be achieved.

[0090] The Figures 5 to 8 show schematic cross-sections through X-ray tubes according to the invention perpendicular to the respective X-ray axis RA in various embodiments, each in the region of the windings 16 and the straightening bodies 23. The arrangement of angular positions at which the respective straightening bodies 23 can be advantageously arranged in the casting chamber 22 between the outer casting mold 21 and the inner casting mold 20 is illustrated by way of example. The location or projection of the tubes 9a, 10a is shown in dashed lines.

[0091] In the embodiment of Fig. 5The straightening bodies 23 are designed as slotted bars 24, with two (N=2) inner slotted bars 25a, 25b and two (N=2) outer slotted bars 26a, 26b being provided. An inner slotted bar 25a, 25b and an outer slotted bar 26a, 26b are located opposite each other and clamp the hoses 9a, 10a between them. The inner slotted bars 25a, 25b are supported on the inner casting mold 20. The outer slotted bars 26a, 26b are supported on the outer casting mold 21. The angular positions of the two inner slotted bars 25a, 25b are offset from each other by 180°, and the angular positions of the outer slotted bars 26a, 26b are offset from each other by 180°. The arrangement of the angular positions of the straightening bodies 23 has a 2-fold rotational symmetry.

[0092] In the embodiment of Fig. 6The straightening bodies 23 are also designed as slotted bars 24, with four (N=4) inner slotted bars 25a, 25b, 25c, 25d and four (N=4) outer slotted bars 26a, 26b, 26c, 26d being provided. An inner slotted bar 25a, 25b, 25c, 25d and an outer slotted bar 26a, 26b, 26c, 26d are located opposite each other and clamp the hoses 9a, 10a between them. The inner slotted bars 25a, 25b, 25c, 25d are supported on the inner casting mold 20. The outer slotted bars 26a, 26b, 26c, 26d are supported on the outer casting mold 21. The angular positions of the four inner slot bars 25a, 25b, 25c, 25d are offset from each other by 90°, and the angular positions of the outer slot bars 26a, 26b, 26c, 26d are offset from each other by 90°. The arrangement of the angular positions of the straightening bodies 23 here has a 4-fold rotational symmetry.

[0093] In the embodiment of Fig. 7The straightening bodies 23 are again designed as slotted bars 24, with two (N=2) inner slotted bars 25a, 25b and two (N=2) outer slotted bars 26a, 26b being provided. The inner slotted bars 25a, 25b are supported on the inner casting mold 20. The outer slotted bars 26a, 26b are supported on the outer casting mold 21. The angular positions of the two inner slotted bars 25a, 25b are offset from one another by 180°, and the angular positions of the outer slotted bars 26a, 26b are offset from one another by 180°. The angular positions of the inner slotted bars 25a, 25b are offset from one another by 90° compared to the angular positions of the outer slotted bars 26a, 26b. The hoses 9a, 10a are also held clamped by the straightening bodies 23 here, whereby the hoses 9a, 10a in this embodiment should have a certain minimum stiffness against radial compression and stretching (against an "oval deformation") so that a good clamping effect of the straightening bodies 23 occurs.The arrangement of the angular positions of the straightening bodies 23 has a 2-fold rotational symmetry.

[0094] It should be noted that the groove bars 24 can run parallel to the tube axis RA; in this case, the grooves must be introduced into the respective bar with an inclination corresponding to the pitch of the double helix of the tubes 9a, 10a. Alternatively, the groove bars 24 can also run with grooves introduced perpendicular to their direction of extension and then be arranged in the casting chamber 12 with an inclination to the tube axis RA that corresponds to the pitch of the tubes 9a, 10a. It should also be noted that the inner groove bars 25a-25d can be supported not only on the inner casting mold 20, but alternatively or additionally also on each other, in particular wherein the inner groove bars 25a-25d form partial shells (in particular half shells or quarter shells) that encompass the inner casting mold (not shown in detail).

[0095] In the embodiment of Fig. 8 The straightening bodies 23 are designed as perforated plates 27, with three (N=3) perforated plates 28a, 28b, 28c being provided, whose angular positions are offset by 120° from one another. The perforated plates 27 are each supported with their plates 27a (or their side edges) on both the inner casting mold 20 and the outer casting mold 21. The hoses 9a, 10a are guided in the holes 27b of the plates 27a. The arrangement of the angular positions of the straightening bodies 23 here has a 3-fold rotational symmetry.

[0096] The Figures 9 to 11 schematically illustrate the sequence in the production of an X-ray tube 1 according to the invention. By way of example, an X-ray tube 1 as in Fig. 1 described. Schematic longitudinal sections along the tube axis RA are shown.

[0097] The production begins with the provision of a partially manufactured X-ray tube 100, essentially comprising the ceramic body 3, to which the anode 4 and the cathode housing 2 are already attached, cf. Fig. 9 . The cathode housing 2 is directed downwards.

[0098] Then the casting chamber 22 is prepared by (in basically any order) the outer mold 21 is placed on the ceramic body 3, the inner mold 20 (here a socket 19 including connection pole 18) is placed within the outer mold 21, and the straightening bodies 23 and the tubes 9a, 10a are arranged in the area between the inner mold 20 and the outer mold 21. The state achieved thereafter is shown in Fig. 10 shown. The hoses 9a, 10a are held in position by the straightening elements 23, here the grooves 24b. The casting chamber 22 is open at the top.

[0099] Then, a liquid, hardenable plastic casting material 32, which is selected, for example, as a silicone, is poured into the casting chamber 22. The casting material 32 is most easily poured into the casting chamber 22 from above. The liquid casting material 32 is distributed throughout the available casting chamber 22 up to a surface 32a of the casting material 32. The casting material 32 reaches, in particular, between the windings 16 and the inner casting mold 20, between the windings 16 and the outer casting mold 21, and axially between adjacent windings 16. The casting material 32 thus encloses the hoses 9a, 10a and also the straightening bodies 23. The filled state of the casting chamber 22 is shown in Fig. 11shown. The liquid casting material 32 is then cured; typically, a certain amount of time is allowed for curing and / or heat is applied. After the casting material 32 has cured, the cast body 12 and the X-ray tube 1 are completely finished. In this variant, the outer casting mold 21 remains on the X-ray tube 1; the outer casting mold 21 can be covered with lead foil for grounding and radiation protection (not shown). With the anode 4 cooled by a coolant, e.g., deionized water, in the hoses 9a, 10a, and with high voltage applied between the anode 4 and the heated hot cathode 6, X-rays can then be generated during operation by means of the X-ray tube 1.

[0100] In another variant, starting from the Fig. 11 shown X-ray tube, after the hardening of the casting material 32, the outer casting mold of the casting body is removed; a corresponding X-ray tube 1 with the outer casting mold removed is shown in Fig. 12shown. Of the cast body, a remaining cast body 12a then remains in the X-ray tube 1, which is essentially formed by the casting chamber 22 filled with hardened casting material 32 (including the cast-in straightening body(s) and the cast-in hose sections) and the inner casting mold 20. A (radially outer) side surface 32b of the hardened casting material 32 or of the filled casting chamber 22 is accordingly exposed; this side surface 32b can be covered with a lead foil for grounding and radiation protection (not shown). In this variant, the outer casting mold can be used multiple times (and is then usually designed in several parts for radial molding and permanently arranged at a casting station, not shown). The Fig. 12 X-ray tube 1 shown can be used in the same way as the Fig. 11 The X-ray tube shown can be used in operation to generate X-rays. List of reference symbols

[0101] 1X-ray tube 2Cathode housing 3Ceramic body 4Anode 4aTop of the anode ("target") 4bAnode channels for coolant (in the anode body) 5Evacuated space 6Hot cathode 7aGround connection 7bPower connection (for heating current) 8Shielding 9Inlet line 9aInlet line hose 9bCoolant connection (inlet line) 10Drain line 10aDrain line hose 10bCoolant connection (drain line) 11Insulation body 12Casting body 12aRemaining casting body 13Radiation exit window,here beryllium window 14aTube of the inlet line 14bTube of the outlet line 15Recess 16Winding 17Contacting element 18Connecting pole 19Socket 20Inner casting mold 21Outer casting mold 22Casting chamber 23Directing body 24Slotted bar 24aBar 24bGroove 25a-25dInner slotted bars 26a-26dOuter slotted bars 27Perforated plate 27aPlate 27bHole 28a-28dPerforated plates 29Conical front end of the casting body 30Circular recess 31Cable 31aSheath 31bCore 32Casting material 32aSurface (casting material) 32bSide surface (casting material) 100Partially manufactured X-ray tube AAAxial distance AAGradient Distance between anode and cathode casing AEKaxial extension of the ceramic body GRRlargest radius of the recess KRRsmallest radius of the recess RRadius of the winding RATube axis RKouter radius of the ceramic body at the rear RAAradial distance to the outside RAIradial distance to the inside TRaxial depth of the recess , Reference list

[0102] [1] WO 2008 / 148426 A1 [2] DE 10 2017 217 181 B3 [3] US 10,714,300 B2 [4] Firmendruckschrift "OEG-92J Industrial X-Ray tube", Version 2021, der Varex Imaging Corporation, Salt Lake City, UT 84104, USA. [5] DE 10 2008 017 153 A1 [6] US 2012 / 0 076 278 A1 [7] JP 2015-232 944 A

Claims

1. An X-ray tube (1), which comprises a cathode housing (2) having a radiation exit window (13), a cooled anode (4), a cathode, in particular a hot cathode (6), an insulation body (11) for electrical insulation of a high-voltage potential of the anode (4), a supply line (9) for coolant to the anode (4) and a discharge line (10) for coolant from the anode (4), the supply line (9) and the discharge line (10) respectively comprising a plurality of turns (16) in the insulation body (11); characterized in that the insulation body (11) comprises a ceramic body (3) and a potted body (12), the anode (4) and the cathode housing (2) being fastened on the ceramic body (3) and the potted body (12) being fastened on the ceramic body (3), that the potted body (12) comprises an inner mold (20) and, at least temporarily during the production of the X-ray tube (1), an outer mold (21), that the supply line (9) and the discharge line (10) are respectively configured with a hose (9a, 10a), which forms the plurality of turns (16), in a potting space (22) between the outer mold (21) and the inner mold (20), that at least one plastic directing body (23), by which the hoses (9a, 10a) are aligned in the potting space (22), is arranged in the potting space (22) so that the turns (16) of the hoses (9a, 10a) are respectively separated from the outer mold (21) and the inner mold (20), and in that the potting space (22) is filled with a plastic potting compound (32) in a cured state so that the intermediate spaces between the turns (16) on the one hand and the outer mold (21) and the inner mold (20) on the other hand are occupied by the plastic of the at least one directing body (23) and / or the plastic of the potting compound (32).

2. The X-ray tube (1) as claimed in claim 1, characterized in that with the at least one directing body (23), the hoses (9a, 10a) are furthermore aligned in the potting space (22) so that the turns (16) of the hoses (9a, 10a) are also separated from one another, and in that the potting space (22) is furthermore filled with the potting compound (32) so that the intermediate spaces between the turns (16) are also occupied by the plastic of the at least one directing body (23) and / or the plastic of the potting compound (32).

3. The X-ray tube (1) as claimed in claim 1 or 2, characterized in that the ceramic body (3) has a circumferential indentation (30) between the cathode housing (2) and the anode (4) on a front side facing toward the anode (4), and in that the ceramic body (3) has a central recess (15) on a rear side of the ceramic body (3) facing toward the potted body (12).

4. The X-ray tube (1) as claimed in claim 3, characterized in that the hoses (9a, 10a) are arranged partially in a region of the central recess (15) of the ceramic body (3), in particular with in each case at least one half-turn (16) of the hoses (9a, 10a) and / or at least 10% of the length of the hoses (9a, 10a) being arranged in the central recess (15) of the ceramic body (3).

5. The X-ray tube (1) as claimed in one of claims 1 to 4, characterized in that the inner mold (20) is configured as a bush (19) for a high-voltage plug for connection to the anode (4).

6. The X-ray tube (1) as claimed in one of claims 1 to 4, characterized in that the inner mold (20) is configured as a cable (31) which comprises an insulating sheath (31a) and a core (31b) running in the sheath (31a), to which the anode (4) is connected.

7. The X-ray tube (1) as claimed in one of the preceding claims, characterized in that the at least one directing body (23) and the potting compound (32) consist of the same plastic.

8. The X-ray tube (1) as claimed in claim 7, characterized in that the plastic of the potting compound (32) comprises a silicone or an epoxy resin or a polyurethane.

9. The X-ray tube (1) as claimed in one of the preceding claims, characterized in that a plurality of directing bodies (23) are arranged in the potting space (22), in particular with the directing bodies (23) in each case being arranged clamped - between the inner mold (20) and the outer mold (21) - and / or between the hoses (9a, 10a) on the one hand and the inner mold (20) or the outer mold (21) on the other hand.

10. The X-ray tube (1) as claimed in claim 9, characterized in that the directing bodies (23) are arranged at angular positions in a respective section plane perpendicular to a tube axis (RA) of the X-ray tube (1), the angular positions forming a rotationally symmetrical arrangement with respect to the tube axis (RA).

11. The X-ray tube (1) as claimed in claim 10, characterized in that N directing bodies (23) support the hoses (9a, 10a) toward the inner mold (20) and N directing bodies (23) support the hoses (9a, 10a) toward the outer mold (21), 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 (1) as claimed in claim 11, characterized in that the N directing bodies (23) which support the hoses (9a, 10a) toward the inner mold (20) and the N directing bodies (23) which support the hoses (9a, 10a) toward the outer mold (21) 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 (1) as claimed in one of the preceding claims, characterized in that one or more directing bodies (23) of the at least one directing body (23) are configured as a perforated plate (27, 28a-28c) comprising a plate (27a) and a plurality of holes (27b) in the plate (27a), through which the hoses (9a, 10a) are guided, in particular with a respective perforated plate (27, 28a-28c) being arranged clamped between the inner mold (20) and the outer mold (21).

14. The X-ray tube (1) as claimed in one of the preceding claims, characterized in that one or more directing bodies (23) of the at least one directing body (23) are configured as a grooved bar (24) comprising a bar (24a) and a plurality of grooves (24b), in particular semicircular grooves (24b), into which the hoses (9a, 10a) are placed, in particular with a respective grooved bar (24) being arranged clamped between the hoses (9a, 10a) on the one hand and the inner mold (20) or the outer mold (21) on the other hand.

15. The X-ray tube (1) as claimed in claim 14, characterized in that grooved bars (25a-25d) which support hoses (9a, 10a) toward the inner mold (20) and grooved bars (26a-26d) which support hoses (9a, 10a) toward the outer mold (21) are respectively arranged lying opposite one another pairwise.

16. The X-ray tube (1) as claimed in one of the preceding claims, characterized in that the turns (16) of the hoses (9a, 10a) are wound around a tube axis (RA) and are sequenced along a tube axis (RA).

17. The X-ray tube (1) as claimed in claim 16, characterized in that the turns (16) have a constant radius (R) with respect to the tube axis (RA), in particular with the outer mold (21) and the inner mold (20) being configured substantially in the form of the lateral surface of a cylinder and coaxially with respect to the tube axis (RA), so that the turns (16) have a constant radial spacing (RAA) with respect to the outer mold (21) and furthermore the turns (16) have a constant radial spacing (RAI) with respect to the inner mold (20).

18. The X-ray tube (1) as claimed in claim 17, characterized in that the turns (16) have a constant spacing (AA) with respect to one another in the axial direction.

19. The X-ray tube (1) as claimed in claim 16, characterized in that the turns (16) have a radius (R) with respect to the tube axis (RA) which increases away from the anode (4), in particular with the outer mold (21) and the inner mold (20) being configured substantially in the form of the lateral surface of a cylinder and coaxially with respect to the tube axis (RA), so that the turns (16) have a radial spacing (RAA) with respect to the outer mold (21) which decreases away from the anode (4) and furthermore the turns (16) have a radial spacing (RAI) with respect to the inner mold (20) which increases away from the anode (4).

20. The X-ray tube (1) as claimed in claim 19, characterized in that the turns (16) 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 (4).

21. The X-ray tube (1) as claimed in one of claims 1 to 20, characterized in that after the production of the X-ray tube (1), the outer mold (21) remains on the rest of the potted body (12a).

22. The X-ray tube (1) as claimed in one of claims 1 to 20, characterized in that after the production of the X-ray tube (1), the outer mold (21) is removed from the rest of the potted body (12a).

23. A method for producing an X-ray tube (1) as claimed in one of the preceding claims, having the steps: a) in order to set up the potting space (22), the outer mold (21) is arranged in a sealing manner on a rear side of the ceramic body (3) facing away from the anode (4) and the inner mold (20) is arranged in front of the rear side of the ceramic body (3), and the at least one plastic directing body (23) and the hoses (9a, 10a) are arranged in the potting space (22) between the inner mold (20) and the outer mold (21), with the at least one directing body (23) aligning the hoses (9a, 10a) in the potting space (22) in such a way that the turns (16) of the hoses (9a, 10a) are respectively separated from the outer mold (21) and the inner mold (20), and preferably the turns (16) are also separated from one another, b) the potting space (22) is filled with the plastic potting compound (32) in a liquid state so that the intermediate spaces between the turns (16) on the one hand and the outer mold (21) and the inner mold (20) on the other hand, and preferably also the intermediate spaces between the turns (16), are occupied by the plastic of the at least one directing body (23) and / or the plastic of the potting compound (32), c) the plastic potting compound (32) is cured.

24. The method as claimed in claim 23, characterized in that an X-ray tube (1) as claimed in claim 21 is produced using the method, the outer mold (21) remaining on the rest of the potted body (12a) after step c).

25. The method as claimed in claim 23, characterized in that an X-ray tube (1) as claimed in claim 22 is produced using the method, the method furthermore comprising a step d) the outer mold (21) is removed from the rest of the potted body (12a).