Abstract: A high-capacity x-ray tube particularly for use in medical technology in CT apparatuses, has a vacuum housing containing a cathode and a rotatably mounted anode. The anode plate of the anode is connected by a solder connection to the one end of a load-bearing part, the other end of which is attached to the bearing shaft of a drive for placing the anode in rotation. The mechanical strength of the connection location between the anode plate and the load-bearing part is improved by the connection being formed by a positive fit, designed such that the connection surfaces are subjected substantially only to compression given rotation of the anode.

Abstract: An energy-absorbing device (78) for an imaging tube (18) includes an energy-absorbing body (82). The energy-absorbing body (82) is fluidically coupled to a housing (60) of the imaging tube (18) and absorbs the kinetic energy generated within the imaging tube (18). The kinetic energy may be generated from the separation of material fragments from a rotating target (74) within the housing (60).

Abstract: An X-ray source has an evacuated housing containing an interior space and a housing projection having a projection interior communicating with the interior space. A cathode is mounted in the projection interior and an anode is mounted in the interior space. Two tubes proceed substantially parallel to each other through the projection and are sealed relative to the projection interior, the two tubes being disposed on opposite sides of an electron beam that proceeds from the cathode to the anode during operation of the X-ray source. An electromagnetic electron beam deflector has a U-shape with two legs that are respectively disposed in the tubes. The electron beam deflector is controllable to generate a magnetic field that deflects the electron beam to set a position of the focus on the anode.

Abstract: An x-ray source with an x-ray source target are provided. The x-ray source includes an electron source. The x-ray source also includes an x-ray transmission window. The x-ray source also includes an x-ray source target located between the electron source and the window, wherein the target is arranged to receive electrons from the electron source to generate x-rays in the x-ray source target, and a rotational mechanism adapted to rotate the x-ray source target. A method of producing x-rays and an x-ray target are also provided.

Abstract: A dental x-ray apparatus (10) includes a tube head (11) formed from a cast zinc material. Structural components of tube head (11) include such component (20) formed from a plastic material impregnated with a high molecular weight substance, such as barium sulfite. X-ray apparatus 10 has a control panel (15) in close proximity to the tube head (11), and is preferably DC powered.

Abstract: The present invention provides an x-ray source including an electron-generation chamber with an electron beam source that emits electrons and a target chamber with a support structure and a target positioned within the support structure. The emitted electrons travel in a direction substantially parallel to a longitudinal axis extending between the electron-generation chamber and the target chamber towards the target and bombard the target to generate x-rays. The target is movable, while being bombarded with electrons, with respect to the support structure in at least one direction perpendicular to a longitudinal axis.

Abstract: An integrated bearing assembly is provided, comprising a bearing housing defining an axial cavity in which a shaft is disposed. The shaft is rotatably supported by at least two bearing sets. The axial cavity defines three regions, each having distinct diameters. A pair of first regions defines cavity diameters sufficient to receive the bearing sets. A pair of second regions defines cavity diameters such that a small gap is defined between the inner surface of the cavity and the shaft. The third region cooperates with the shaft to define a cylindrical volume containing a coolant. Wettable coatings are utilized in the cylindrical volume to allow free flow of, and maximum contact with, the coolant. Non-wettable coatings are provided in the second regions to contain the coolant. The second regions also function as bearing spacers, thus simplifying bearing assembly design, assembly, and performance.

Abstract: The invention relates to a device (1) for generating X-rays (57). The device comprises a source (7) for emitting electrons (53) and a liquid metal for emitting X-rays as a result of the incidence of electrons. The device further comprises a displacing member (11) for displacing the liquid metal through an impingement position (55) where the electrons emitted by the source impinge upon the liquid metal. As a result of the flow of liquid metal through the impingement position the heat, which is generated in the impingement position as a result of the incidence of the electrons upon the liquid metal, is transported away from the impingement position. According to the invention, the displacing member (11) has a contact surface (61), which is in contact with the liquid metal in the impingement position (55), and a driving member (31) for moving the contact surface in a direction which, in the impingement position, is substantially parallel to the contact surface.

Abstract: An x-ray tube target assembly 16 is provided. The assembly 16 includes a target disc element 18 having a target bore 22. A target shaft 20 transmits rotational drive to the target disc element 18. The target shaft 20 includes a plurality of axial adjustment slots 30 formed in an upper portion. The plurality of axial adjustment slots 30 are positioned around the target shaft 20 to form a plurality of partial circumferential ribs 36. The plurality of partial circumferential ribs 36 are brazed to the target bore 22.

Abstract: An X-ray inspection system is provided comprising an X-ray source which includes an electron gun and beam steering means for alternately directing the electron beam from the gun in a first direction wherein the beam strikes the anode to produce a beam of X-rays which exits the X-ray source, and in a second direction wherein no significant X-ray flux exits the X-ray source. An X-ray detector and means for reading the detector are also provided. The beam steering means and the detector reading means are coordinated so that the detector output is read during a period when no significant X-ray flux exits the source. A method for operating the X-ray inspection system is also provided.

Abstract: An integrated component mounting system that includes a component mounted to a shaft and secured in place by a nut. The component and the nut each define respective annular shaped surfaces. The shaped surfaces are each inclined at a similar angle and are arranged for sliding contact with respect to each other. As the nut is tightened on the shaft, the shaped surface of the nut exerts both radial and axial forces on the shaped surface of the component, thereby automatically centering the component radially on the shaft as well as securing the component at a desired location along the shaft.

Abstract: A rotary component support system for positioning and securing an anode of x-ray tube. The rotary component support system includes a shaft, to which the anode is indirectly mounted, that includes a tapered end and defines a threaded hole. The tapered end of the shaft is engaged by a tapered cavity defined by a mounting piece that is disposed in an aperture defined by the vacuum enclosure of the x-ray tube. The mounting piece defines a hole through which a bolt passes. The bolt engages the threaded hole defined by the support shaft so that as the bolt is tightened, the tapered end of the support shaft is drawn into the tapered cavity of the mounting piece. Due to the tapered geometries, the support shaft self-aligns itself with respect to the mounting piece. A weld at the interface between the bolt and the mounting piece seals the vacuum enclosure.

Abstract: A rotating anode X-ray tube suitable for use in CT installations has a vacuum housing in which a cathode that emits electron beams is rigidly arranged and in which an anode that emits X-rays is rotatably arranged. The anode is arranged at a rotary body that, facing toward the cathode, has a focal path composed of target material that melts during operation of the tube. The rotary body is designed so that the melting target material is held to the anode due to the centrifugal forces of the rotary body when rotating around the cathode.

Abstract: In a method and an apparatus for generating X-ray or EUV radiation, an electron beam is brought to interact with a propagating target jet, typically in a vacuum chamber. The target jet is formed by urging a liquid substance under pressure through an outlet opening. Hard X-ray radiation may be generated by converting the electron-beam energy to Bremsstrahlung and characteristic line emission, essentially without heating the jet to a plasma-forming temperature. Soft X-ray or EUV radiation may be generated by the electron beam heating the jet to a plasma-forming temperature.

Abstract: A bearing assembly for a rotating anode x-ray device. The bearing assembly includes a shaft having a flange at one end for attachment of the anode thereto. The shaft defines front and rear inner races and includes a plurality of extended surfaces. Front and rear outer race elements define front and rear outer races, respectively, corresponding to the front and rear inner races, respectively, defined by the shaft. The front and rear outer race elements cooperate with the shaft to confine front and rear ball sets which facilitate rotary motion of the shaft. A spacer including extended surfaces assists in the positioning of the front and rear outer race elements in a bearing housing. The extended surfaces of the shaft and spacer, in conjunction with emissive coatings provided on various portions of selected components of the bearing assembly, facilitate a relative improvement in heat transfer out of the bearing assembly.

Abstract: An improved x-ray tube is disclosed that eliminates the use of a fluid-filled outer housing for cooling tube components. The present x-ray tube includes a cathode housing in which is disposed a cathode assembly having a filament for producing electrons, and an anode housing in which is disposed a rotary anode for receiving electrons produced by the filament. An adapter plate is sized to hermetically receive therein the cathode assembly and the anode housing, thereby forming a unitary vacuum enclosure and tube housing. The improved x-ray tube is cooled by a combination of air and fluid cooling to reduce the buildup of damaging heat within the vacuum enclosure. The features of the present invention are preferably directed to an anode grounded-type x-ray tube, though other x-ray tube types may benefit therefrom.

Abstract: A high-quality and high-reliability rotary anode target for X-ray tubes, of which the mechanical strength at high temperatures is increased and which is applicable not only to low-speed rotation (at least 3,000 rpm) but also even to high-speed rotation at high temperatures, and also a method for producing it. The rotary anode has a two-layered structure to be formed by laminating an Mo alloy substrate that comprises from 0.2% by weight to 1.5% by weight of TiC with the balance of substantially Mo, and an X-ray generating layer of a W—Re alloy that overlies the substrate.

Abstract: An x-ray tube (20) includes an evacuated envelope (26). Mounted within the evacuated envelope are a cathode (23) and a rotatbly supported anode (30). A rotor (70) is included for rotatably driving the anode. The rotor (70) is electrically insulated from the anode (30) by a disk (76) comprised of an insulating material.

Abstract: A method and apparatus for a rotatable anode of an x-ray tube. The anode having an axis of rotation and includes a solid thin plate target having a substantially planar base surface extending from the axis of rotation to a periphery outlining the base surface, wherein the plate target includes target material for generating x-rays selected from a group of high-Z materials. The plate target has a thickness of about 1 mm or less. The method includes fabricating the thin plate target using silicon wafer processing technology using suitable materials for such technology in forming the plate target selected from the group of high-Z materials.

Abstract: An X-ray tube includes a substantially cylindrical rotor having an anode target fixed thereto, a substantially columnar stationary shaft coaxially arranged inside the rotor with a bearing gap, a dynamic slide bearing having helical grooves and formed between the rotor and the stationary shaft, and a metal lubricant supplied to the grooves and to the gap. An axial bore is formed in the shaft to extend in the longitudinal direction of the shaft, and an insertion rod is inserted into the axial bore such that a space extending in the longitudinal direction of the shaft is formed between an inner circumferential surface of the axial bore and an outer circumferential surface of the insertion rod. The space acts as at least one lubricant reservoir that is configured to store the metal lubricant.

Abstract: In a preferred embodiment, an X-ray producing device, including: an X-ray tube; a cathode disposed in the X-ray tube to produce a stream of electrons; and a spherical anode disposed in the X-ray tube to have impinged on a point thereon the stream of electrons and to produce thereby a stream of X-rays.

Abstract: A source of photons includes a discharge chamber, first and second groups of ion beam sources in the discharge chamber and a neutralizing mechanism. Each of the ion beam sources electrostatically accelerates a beam of ions of a working gas toward a plasma discharge region. The first group of ion beam sources acts as a cathode and the second group of ion beam sources acts as an anode for delivering a heating current to the plasma discharge region. The neutralizing mechanism at least partially neutralizes the ion beams before they enter the plasma discharge region. The neutralized beams and the heating current form a hot plasma that radiates photons. The photons may be in the soft x-ray or extreme ultraviolet wavelength range and, in one embodiment, have wavelengths in a range of about 10-15 nanometers.

Abstract: In an X-ray diagnostic apparatus, the rotation anode of an X-ray tube is placed in rotation at a given low speed prior to examination of an object under examination by fluoroscopy. For fluoroscopy, the rotational speed of the rotation anode is switched from the low speed to a given medium speed. For X-ray photography, the rotational speed of the rotation anode is switched from the medium speed to a given high speed.

Abstract: A multiple row spiral grooved bearing assembly 26 for use in a rotating anode X ray tube device 10 has an intermediate race 32 having a spiral grooved inner 34 and outer 36 surface placed between an outer housing 28 and an inner bearing shaft 30. A layer of gallium 42, 44 is interposed between the spiral grooved inner surface 34 and the inner bearing shaft 30 and between the spiral grooved outer surface 36 and outer housing 28 to provide lubrication for the surfaces of the intermediate race 32. The intermediate race 32 reduces the relative velocity between moving parts, thereby reducing heat generation of the bearing assembly 26 for a given anode rotation speed. This enables higher target 14 velocities, and hence higher focal spot power, available to the x-ray tube device 10 as compared with traditional ball-type bearing designs.

Abstract: Conventional x-ray tubes are designed as stationary or rotating-anode tubes. While the former are restricted in output, the latter are of complicated design. An x-ray tube is provided having an anode comprising a stationary shell and a rotating core mounted therein. Consequently, it is more compact than a rotating-anode tube and permits higher focal spot loads than a stationary-anode tube. The tube can be used for imaging procedures in medical diagnostics and in material testing.

Abstract: An X-ray tube assembly includes an anode, a cathode, and an X-ray transparent window. The anode includes an X-ray-producing target having a surface. The cathode has an electron-beam axis which intersects the target surface at a focal point and which is oriented at a first angle, with respect to the target surface, wherein the first angle is generally twenty degrees. The window includes a surface having a center point. A line between the focal and center points makes a second angle, with respect to the target surface, wherein the second angle is generally seven degrees. A method for producing X-rays employs these angles.

Abstract: A multiple row x-ray tube bearing assembly is provided, including an inner bearing member, an outer bearing member, and a free rotational intermediate race member positioned between the inner bearing member and the outer bearing member such that the inner bearing member and the outer bearing member may rotate independently of each other.

Abstract: The invention relates to an X-ray tube which includes a device for generating and focusing an electron beam on a target material. In order to avoid the problems of inadmissible heating of the anode while attempting to increase the electron beam density, according to the invention a gaseous target material contained in a chamber is used to generate the X-rays; this target material can be heated to a substantially higher temperature without the anode being damaged.

Abstract: A rotation monitoring system (70) detects the rotational speed of an anode (10) of an x-ray tube during use. The system (70) includes a detector (72), which detects a pulse of secondary x-rays generated by the interaction of a stream (C) of electrons with a known defect (83) on a surface (84) of the anode. The detector may be position inside or outside a vacuum envelope (14) of the x-ray tube. The stream of electrons is supplied by a secondary source (80), separate from a main source (18) of electrons used to generate the primary or working x-ray beam (B) of the x-ray tube. A single pulse is detected with each rotation of the anode, providing a simple method of calculation of the anode rotation speed. Preferably, a feed back loop is used to correct the rotational speed of the anode so that overheating of the anode is avoided and the useful life of the x-ray tube is extended.

Abstract: An X-ray tube comprises a substantially cylindrical rotor having an anode target fixed thereto, a substantially columnar stationary shaft coaxially arranged inside the rotor with a bearing gap, a dynamic slide bearing having helical grooves and formed between the rotor and the stationary shaft, and a metal lubricant supplied to the grooves and to the gap. An axial bore is formed in the shaft in a manner to extend in the longitudinal direction of the shaft, and an insertion rod is inserted into the axial bore such that a space extending in the longitudinal direction of the shaft is formed between the inner circumferential surface of the axial bore and the outer circumferential surface of the insertion rod. The space acts as a lubricant reservoir for storing the metal lubricant.

Abstract: An x-ray tube apparatus comprises a cathode structure emitting an electron beam, a anode target arranged to face the cathode structure, a rotary structure fixed to the anode target, a stationary shaft having bearings arranged between the stationary shaft and the rotary structure for rotatably supporting the rotary structure, and a vacuum envelope provided with an x-ray transmitting window for taking the X-ray generated from the anode target to the outside. The end portion of the stationary shaft on the side of the cathode structure and the other end portion on the side of the anode terminal are fixed to parts of the vacuum envelope. Particularly, the joining portion on the side of the cathode structure is deviant from the axis of rotation of the anode target and the rotary structure and positioned on the side opposite to the cathode structure and the X-ray transmitting window with respect to the axis of rotation.

Abstract: An x-ray tube (20) comprising a cathode (23) and an anode (24) in operative relationship with the cathode (23). The anode (24) is mounted on a stem (32). The x-ray tube includes at least one bearing (58) rotatably receiving the stem (32). The at least one bearing (58) has an outer bearing race (66) in an outer race member, an inner bearing race (62) and a plurality of bearing members (64) operatively disposed between the inner and outer bearing races. The x-ray tube (20) also includes an evacuated envelope (78) which encloses the tube components and receives the outer race member of the at least one bearing (58) in thermally conductive contact along an inner surface (79).

Abstract: The invention relates to a rotary-anode X-ray tube which includes a sleeve bearing which is composed of an inner and an outer bearing segment, the outer bearing segment including intermediate pieces and a holder on which the intermediate pieces bear so as to transfer the bearing forces. Suitable shaping of the external surfaces of the intermediate pieces and the inner surfaces of the holder which contact these outer surfaces ensures that the intermediate pieces become aligned with the bearing surfaces on the inner bearing segment. This strongly reduces the complexity of manufacture.

Abstract: An X-ray radiator with a rotating bulb X-ray tube, with an allocated deflecting magnet system having at least one current-supplied coil for generating a magnetic deflecting field, has a circuit for tapping at least one reference signal representative of the high voltage existing at the X-ray tube. The coil current is adjusted by a control unit depending on this reference signal.

Abstract: Provided are a high-quality and high-reliability rotary anode target for X-ray tubes, of which the mechanical strength at high temperatures is increased and which is applicable not only to low-speed rotation (at least 3,000 rpm) but also even to high-speed rotation at high temperatures, and also a method for producing it. The rotary anode has a two-layered structure to be formed by laminating an Mo alloy substrate that comprises from 0.2% by weight to 1.5% by weight of TiC with the balance of substantially Mo, and an X-ray generating layer of a W—Re alloy that overlies the substrate.

Abstract: A modular X-ray radiator system includes at least one base X-ray radiator with a rotating bulb tube with a cathode that emits an electron beam, an anode, and an arrangement for variably deflecting the electron beam and for adjustment of the size of the focal spot of the electron beam on the anode, and a number of drive mechanisms of varying drive powers which can be selectively attached to one of the base X-ray radiators for the rotating of the rotating bulb tube.

Abstract: A bearing assembly includes: an axial rotatable structure including a cylindrical rotor assembly (including a motor rotor and a plurality of magnetic bearing rotors); a cylindrical stationary shaft; rotating element bearings mechanically coupling the rotatable structure and the stationary shaft; and a cylindrical stator assembly including a motor stator and a plurality of magnetic bearing stators. The magnetic bearing stators and the magnetic bearing rotors forming magnetic bearings magnetically coupling the rotor and stator assemblies. Command feedforward of electrical current can be provided to at least some of the bearings to achieve appropriate radial forces for respective operating trajectories.

Abstract: A system and method are proposed for cooling the anode of an X-ray tube. A bearing shaft associated with the anode has an associated single rotating seal there around, and contains a liquid metal. A primary liquid metal flow path is used to transfer heat from the anode, and a secondary liquid metal flow path is provided to seal the single rotating seal. Accordingly, the present invention provides an effective means for containing liquid metal in the bearing shaft of an anode assembly, and using the liquid metal to cool the anode of the X-ray tube.

Abstract: The invention relates to an X-ray tube having a liquid metal target. The electrons emitted by the electron source (3) enter the liquid metal through a thin window (2) and produce X-rays therein. The liquid metal, having a high atomic number, circulates under the influence of a pump so that the heat produced by the interaction with the electrons in the window and the liquid metal can be dissipated. The heat generated at this area is dissipated by a turbulent flow, thus ensuring effective cooling.

Abstract: A method and apparatus for reducing off-focus radiation by modifying a shape of a rotating target anode disposed within a cathode grounded x-ray tube. The shape of the target anode body is modified such that surfaces of the target anode which could otherwise direct the greatest amounts of off-focus radiation toward an x-ray sensitive imaging device are angled or shortened so as to redirect the off-focus radiation away from a focal direction. These modifications to surfaces of the target anode body include modifying a front surface, a side or edge surface, and a back surface.

Abstract: An x-ray tube (10) includes an anode (14) connected to a mechanical drive (36). The mechanical drive oscillates the anode in a gyrating motion relative to a body of the x-ray tube. The mechanical drive is operatively connected to the anode via a bellows assembly (16) and is capable of rocking the anode in two axes simultaneously. The preferred anode is shaped in a shperical section (28) providing a fixed focal distance between the anode and a cathode (20) regardless of relative position of the anode within the body. An electron shield (40) is disposed between the cathode and the anode and has an opening along a preferred path for electron travel. Improved heat exchange is provided by applying a heat transfer agent to an obverse side of the anode which is preferably located outside of a vacuum envelope (18) defined by the x-ray tube body, the anode, and the bellows.

Abstract: An x-ray target assembly is formed by passing a rotary shaft through the center hole of a graphite disk such that the back surface of the disk rests on a flange part of the rotary shaft and the front surface is contacted by a nut which engages with the tip of the rotary shaft. Annular brazing materials are placed adjacent contact areas where the disk contacts the rotary shaft and the nut such that braze joints are made to secure the disk with the nut and the rotary shaft. Grooves may be formed on the surfaces of the nut and the flange part of the rotary shaft which contact the disk such that the brazing material can more efficiently fill the gaps between contacting surfaces.

Abstract: The invention relates to a rotary-anode X-ray tube which includes a sleeve bearing comprising an inner bearing member (9) and an outer bearing member (8). The inner bearing member itself includes three bearing portions, the first (94) of which takes up the axial bearing forces whereas the second bearing portion takes up the radial bearing forces and the third bearing portion (96) interconnects the first and the second bearing portion in such a manner that the symmetry axis (11) of the first or the second bearing portion can perform a swaying motion about the axis of rotation (10) during rotation of the two bearing members. Adequate bearing capacity is thus ensured even when the axial bearing surfaces do not extend exactly perpendicularly to the radial bearing surfaces.

Abstract: An x-ray tube includes an anode, a cathode, and an electrode disposed in an evacuated envelope. The electrode is positioned such that the electrode is remote from an area in immediate proximity to the envelope. An electric field defined by electrode is of sufficient strength such that arcing preferentially occurs between the electrode and the anode as opposed to occurring between the cathode and anode. The electrode is further situated such that metal sputtered from the electrode substantially falls in a define region on the anode and serves as an active getter for pumping gas from the envelope. The electrode is composed of an active metal which, upon being passively heated by the anode, also acts as a getter material to aid in pumping gas from the envelope.

Abstract: An explosive forming process provides an anode (10) suitable for use in a high energy x-ray tube. The process includes applying a shaped charge (54, 80, 90, 92) to a refractory material which has been formed in the general shape of the anode. The configuration of the charge is calculated to provide a target area (16) on the anode of uniform, high density which does not tend to outgas in the high vacuum conditions of the x-ray tube. The explosive process is capable of forming anodes with much larger diameters than is possible with conventional forging techniques.

Abstract: An X-ray tube assembly including a cathode having an electron emitting surface, a rotatable anode having an X-ray target surface, and a vacuum-enclosing rotatable frame surrounding, and spaced apart from, the electron emitting surface and the X-ray target surface. The frame is hermetically attached to the anode, and the frame includes a totally-annular and X-ray-transparent window ring. Load-carrying bearings are located outside the vacuum of the frame and rotatably support the frame and the anode.

Abstract: An X-ray tube bearing assembly has a first X-ray tube shaft with first and second ball-bearing raceway surfaces which are integral with (i.e., either monolithic portions of or fixedly attached to) the first shaft and has a second X-ray tube shaft with a third ball-bearing raceway surface which is integral with the second shaft. A ball-bearing race, which is non-integral with (i.e., neither a monolithic portion of nor fixedly attached to) the two shafts, has a fourth ball-bearing raceway surface. A first set of ball bearings is located between the first and third raceway surfaces, and a second set of ball bearings is located between the second and fourth raceway surfaces. Preferably, an anode target surface is attached to the first shaft, and a mechanism is provided to preload the ball-bearing race.

Abstract: An x-ray tube has an evacuated housing rotatable around a rotational axis with a cathode and an anode being rigidly mounted in the housing so as to rotate therewith. The cathode emits electrons which are accelerated with an electrical field so as to strike the anode. An electromagnetic system for deflecting and focusing the electron beam has a number of current-permeated coil elements, whereby the coil elements are arranged a common carrier that at least partially surrounds the housing.

Abstract: A method for assembling a rotating X-ray tube structure ensures balance retention during the life of the tube. The X-ray tube structure has a cathode for emitting electrons, and a rotor and a bearing assembly for facilitating rotation of an anode. At least one joint is identified in the X-ray tube structure and interference fit assembly is used to eliminate shifts at the joint. The interference fit assembly is particularly advantageous for eliminating even the minutest shifts in the main joints of the anode assembly. Interference fit assembly can be applied between the rotor and the anode target to provide a first joint having balance retention; and interference fit assembly can be applied between the bearing assembly and the rotor to provide a second joint having balance retention.

Abstract: An X-ray tube having a vacuum housing rotatable around a rotational axis, a ring-shaped anode connected to the vacuum housing whose center axis corresponds to the rotational axis, a cathode arranged inside the vacuum housing and that surrounds the rotational axis and that emits electrons radially outward during operation of the X-ray tube, a rotatable support for the vacuum housing, a drive arrangement for turning the vacuum housing and an arrangement for focussing the electron beam proceeding from the cathode to the anode which focus the electron beam such that it strikes the anode in a stationary focal spot.