EP3149760A1 - Générateur de rayons x - Google Patents

Générateur de rayons x

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Publication number
EP3149760A1
EP3149760A1 EP15732170.4A EP15732170A EP3149760A1 EP 3149760 A1 EP3149760 A1 EP 3149760A1 EP 15732170 A EP15732170 A EP 15732170A EP 3149760 A1 EP3149760 A1 EP 3149760A1
Authority
EP
European Patent Office
Prior art keywords
ray generator
temperature
bearing
focal
coolant
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Withdrawn
Application number
EP15732170.4A
Other languages
German (de)
English (en)
Inventor
Jules Hendrix
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Individual
Original Assignee
Individual
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Individual filed Critical Individual
Publication of EP3149760A1 publication Critical patent/EP3149760A1/fr
Withdrawn legal-status Critical Current

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Classifications

    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J35/00—X-ray tubes
    • H01J35/02—Details
    • H01J35/04—Electrodes ; Mutual position thereof; Constructional adaptations therefor
    • H01J35/08—Anodes; Anti cathodes
    • H01J35/10—Rotary anodes; Arrangements for rotating anodes; Cooling rotary anodes
    • H01J35/105—Cooling of rotating anodes, e.g. heat emitting layers or structures
    • H01J35/106—Active cooling, e.g. fluid flow, heat pipes
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J35/00—X-ray tubes
    • H01J35/02—Details
    • H01J35/04—Electrodes ; Mutual position thereof; Constructional adaptations therefor
    • H01J35/06—Cathodes
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J35/00—X-ray tubes
    • H01J35/02—Details
    • H01J35/04—Electrodes ; Mutual position thereof; Constructional adaptations therefor
    • H01J35/08—Anodes; Anti cathodes
    • H01J35/10—Rotary anodes; Arrangements for rotating anodes; Cooling rotary anodes
    • H01J35/101—Arrangements for rotating anodes, e.g. supporting means, means for greasing, means for sealing the axle or means for shielding or protecting the driving
    • H01J35/1017—Bearings for rotating anodes
    • H01J35/104—Fluid bearings
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J35/00—X-ray tubes
    • H01J35/02—Details
    • H01J35/04—Electrodes ; Mutual position thereof; Constructional adaptations therefor
    • H01J35/08—Anodes; Anti cathodes
    • H01J35/10—Rotary anodes; Arrangements for rotating anodes; Cooling rotary anodes
    • H01J35/105—Cooling of rotating anodes, e.g. heat emitting layers or structures
    • H01J35/107—Cooling of the bearing assemblies
    • H—ELECTRICITY
    • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05G—X-RAY TECHNIQUE
    • H05G1/00—X-ray apparatus involving X-ray tubes; Circuits therefor
    • H05G1/08—Electrical details
    • H05G1/26—Measuring, controlling or protecting
    • H05G1/30—Controlling
    • H05G1/36—Temperature of anode; Brightness of image power
    • H—ELECTRICITY
    • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05G—X-RAY TECHNIQUE
    • H05G1/00—X-ray apparatus involving X-ray tubes; Circuits therefor
    • H05G1/08—Electrical details
    • H05G1/26—Measuring, controlling or protecting
    • H05G1/30—Controlling
    • H05G1/46—Combined control of different quantities, e.g. exposure time as well as voltage or current
    • G—PHYSICS
    • G21—NUCLEAR PHYSICS; NUCLEAR ENGINEERING
    • G21K—HANDLING OF PARTICLES OR IONISING RADIATION NOT OTHERWISE PROVIDED FOR; IRRADIATION DEVICES; GAMMA RAY OR X-RAY MICROSCOPES
    • G21K2201/00—Arrangements for handling radiation or particles
    • G21K2201/06—Arrangements for handling radiation or particles using diffractive, refractive or reflecting elements
    • G—PHYSICS
    • G21—NUCLEAR PHYSICS; NUCLEAR ENGINEERING
    • G21K—HANDLING OF PARTICLES OR IONISING RADIATION NOT OTHERWISE PROVIDED FOR; IRRADIATION DEVICES; GAMMA RAY OR X-RAY MICROSCOPES
    • G21K2201/00—Arrangements for handling radiation or particles
    • G21K2201/06—Arrangements for handling radiation or particles using diffractive, refractive or reflecting elements
    • G21K2201/064—Arrangements for handling radiation or particles using diffractive, refractive or reflecting elements having a curved surface
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J2235/00—X-ray tubes
    • H01J2235/06—Cathode assembly
    • H01J2235/062—Cold cathodes
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J2235/00—X-ray tubes
    • H01J2235/10—Drive means for anode (target) substrate
    • H01J2235/1006—Supports or shafts for target or substrate
    • H01J2235/102—Materials for the shaft
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J2235/00—X-ray tubes
    • H01J2235/10—Drive means for anode (target) substrate
    • H01J2235/108—Lubricants
    • H01J2235/1086—Lubricants liquid metals
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J2235/00—X-ray tubes
    • H01J2235/12—Cooling
    • H01J2235/1225—Cooling characterised by method
    • H01J2235/1245—Increasing emissive surface area
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J2235/00—X-ray tubes
    • H01J2235/12—Cooling
    • H01J2235/1225—Cooling characterised by method
    • H01J2235/1262—Circulating fluids
    • H01J2235/1275—Circulating fluids characterised by the fluid
    • H01J2235/1279—Liquid metals
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J2235/00—X-ray tubes
    • H01J2235/12—Cooling
    • H01J2235/1225—Cooling characterised by method
    • H01J2235/1262—Circulating fluids
    • H01J2235/1287—Heat pipes

Definitions

  • the invention relates to an X-ray generator.
  • a liquid-cooled X-ray rotary anode with a arranged in a high vacuum tube housing cathode and one of these opposite rotary anode is known.
  • this rotary anode the heat generated by the electron current in the X-ray generation on the rotary anode from the rotating rotary anode is discharged to a fixed, cooled from the inside with a first liquid cooler.
  • a cooled rotary anode without rotary feedthrough for a coolant is placed in a high vacuum.
  • a second liquid is arranged with low vapor pressure, which transfers the heat from the rotary anode to the radiator.
  • the first liquid is water and the second liquid is a metal alloy which is liquid at room temperature or a high-vacuum oil.
  • WO 2007/020097 A1 The basic idea of WO 2007/020097 A1 is to use the so-called heat-pipe principle for the cooling of the anode.
  • the purpose of this is that between the focal track and the bearing parts there is a liquid which evaporates at the evaporation surface.
  • the evaporation surface is heated by the impact of the electrons on the burning surface.
  • This vapor then passes to the bearing parts, where there is a negative pressure due to a temperature gradient and condensation occurs.
  • the condensation surface results from the temperature gradient that occurs between the evaporation surface and the bearing parts, which also fulfill the function of a condensation surface.
  • the return transport of the condensate to the fuel track is done by the centrifugal forces of the rotating anode. In this way, the heat cycle of a heat pipe is closed.
  • the parts of the bearing are gas-tight connected to the focal path. This takes into account the fact that the rotary anode is in a high vacuum. Furthermore, the bearing is preferably designed as a sliding bearing.
  • a rotary anode X-ray tube in which an improvement in the structure of a bearing for supporting the rotary anode is to be achieved in particular.
  • the bearing part of the rotary anode is formed by a hydrodynamic pressure sliding bearing having spiral spiral bearing surfaces and using a metal lubricant of gallium or a gallium indium tin alloy, for example, which is liquid in operation.
  • DE 102005060234 A1 shows a radiation emission device, for example an X-ray tube, with a valve via which optionally a liquid lubricant based on gallium, indium and tin can be filled in or the housing of the tube can be evacuated. The evacuation also takes place during the operation of the X-ray tube.
  • the document DE 19832032 C1 describes an X-ray tube and a catheter with such an X-ray tube. This must have a very small diameter, whereby it is extremely difficult to supply both a heating current and an acceleration voltage.
  • indirectly heated cathodes are proposed. Their electron emission is to be enhanced by using an emission-enhancing material having a lower electron work function than tungsten as a material or constituent of the emission element in the indirectly heated cathode, possibly also as a layer. As a result, sufficient tube currents can be achieved even at lower temperatures than those for tungsten cathodes.
  • barium oxide is called with a temperature of about 1000 ° C.
  • the cathode is arranged on the central axis of a vacuum housing.
  • the document EP 0378273 A2 describes a rotary anode X-ray tube with a slide bearing which is filled with a liquid lubricant, preferably with a gallium alloy, in particular gallium indium tin (Ga-In-Sn).
  • this document shows a closed metal piston, are mounted in the cathode and rotary anode of the X-ray tube.
  • DE 102008062671 B4 shows an X-ray device with a rotary anode. It is called the storage of this rotary anode via a liquid metal sliding bearing, wherein as a suitable liquid metal, for example gallium or a gallium alloy can be mentioned.
  • a suitable liquid metal for example gallium or a gallium alloy can be mentioned.
  • the X-ray tube is installed in a predominantly made of metal, standing under high vacuum housing.
  • the object of the invention is to design an X-ray generator with simple means in such a way that, in a simple, compact design, it is suitable for emitting a very high radiation power even over relatively long time intervals.
  • an X-ray generator of the type mentioned at the beginning contains: a high-temperature, low-temperature, thermal cathode for emitting an electron beam, an anode plate comprising an anode A rotary anode, which is rotatably guided about a rotation axis in a bearing device having between a nenan connected to the rotary anode bearing part and a bearing axis, an electron focusing means for focusing the electron beam onto a focal path along a surface of the anode plate and a condensation cooling arrangement formed with a present between the focal path and the bearing part of the rotary anode first coolant and a configuration of the bearing axis for a flow through a second coolant, wherein the first coolant of a structural connection formed between the focal track and the bearing part at least from the anode plate is gas-tight enclosure and the liquid metal sliding bearing forms a heat conducting element for transmitting heat energy between the first coolant and the second coolant.
  • the X-ray generator according to the invention thus has a cathode which can be operated at low temperatures and nevertheless allows a sufficiently high electron emission for the stated task.
  • a cathode is selected which already has this electron emission at an operating temperature of about 900 ° C. to about 950 ° C., preferably of at least almost 900 ° C. This ensures that despite careful operation of the cathode, a high radiation power can be achieved.
  • By operating the cathode at such a low operating temperature of the energy consumption of the X-ray generator is lowered, reduces the amount of heat dissipated by cooling and achieves a long service life of the cathode and thus of the X-ray generator as a whole.
  • the high-temperature low-temperature thermal cathode is formed as a large-area cathode, that is to say with an electron-emitting surface which is large in relation to its external dimensions.
  • a large electron-emitting surface makes it possible to deliver a high-current electron beam, ie, a large cathode current, at a low current density at the electron-emitting surface and hence low cathode load, ie a low cathode current to electron emission surface-emitting ratio, whereby the cathode reaches a long service life.
  • the large-area cathode is also mechanically more stable and robust due to its design and thus also enables a longer service life.
  • the cathode can basically be formed as a pure tungsten cathode; however, the high-temperature, low-temperature, thermal-emitting cathode is preferably designed as a coated so-called dispenser cathode, by means of which a higher electron emission can be achieved without greater thermal load.
  • impregnated (ie, impregnated) tungsten cathode provided with an alloy of platinum group metal alloy which, in order to produce a comparable current density at the electron emissive surface, provides a further reduction in operating temperature over standard dispenser cathodes ,
  • cathodes containing scandium oxide Such cathodes also allow a reduced operating temperature relative to standard dispenser cathodes to produce a comparable current density. These cathodes are provided with a coating of barium-scandium alloy.
  • a fundamental advantage of the dispenser cathodes as a whole is that a high cathode current can be distributed over a correspondingly large cathode surface in such a way that the current density remains low.
  • Dispenser cathodes have high and uniform electron emission throughout their lifetime.
  • pure tungsten cathodes have the disadvantage of a high vapor pressure and therefore a comparatively shorter life.
  • the liquid metal sliding bearing is preferably formed with an alloy of gallium, indium and tin.
  • the design as a plain bearing allows a structurally simple, robust construction, is maintenance-free and allows a long service life.
  • the alloy of gallium, indium and tin shows a low vapor pressure and a high thermal conductivity, which makes this alloy on the one hand due to their extremely low outgassing preferably suitable for use in vacuum, on the other hand a high efficiency of the liquid metal sliding bearing as a heat conducting element for transferring the heat energy between allows the first and the second coolant.
  • the anode plate is preferably configured with wall regions on which the focal path runs, which form the connection between the focal path and the bearing part and through which a gas-tight enclosed cavity for receiving the first coolant is formed, which on the other hand, adjacent to the focal track and on the other hand to the bearing part.
  • the anode plate is formed with copper, at least in the wall regions on which the focal path runs, at least on its surface to be hit by the electron beam.
  • the anode plate has good electrical conductivities and high thermal conductivity in the region of the focal point.
  • there is no risk of "poisoning" by copper ions which may be released from the anode plate under the influence of the heating by the electron beam and the high DC voltage applied between the rotary anode and the cathode of the X-ray generator during operation. Contamination of the cathode, which would result in a reduction of the electron emission.
  • the rotary anode but in particular the anode plate and the bearing part, made of metal for reasons of mechanical and thermal resistance and to ensure good electrical conductivity.
  • the gas-tight enclosed cavity for receiving the first coolant is arranged to boil the first coolant in the region of the focal path and to condense the first coolant in the region of the bearing part.
  • a condensation cooling is formed between the focal track and the bearing part, by means of which the heat energy occurring along the focal track is dissipated to the bearing part with high efficiency.
  • the cooling device used according to the invention for the rotary anode which is designed as a liquid-condensation cooling arrangement, besides this condensation cooling between the focal track on the anode plate and the bearing part further comprises a heat conduction through the liquid metal slide bearing.
  • the heat energy transferred therefrom is derived from a second coolant flowing through the bearing shaft out of the liquid metal sliding bearing and thus from the X-ray generator to the outside.
  • a second coolant an electrically non-conductive substance is preferably used due to the voltage applied during operation between the rotary anode and the cathode, wherein it is optionally a liquid coolant, for. As oil, or a gaseous coolant, for. As nitrogen or a refrigerant gas is.
  • the heat energy occurring in particular in the region of the focal point is dissipated better and faster in the case of the high expected thermal stresses of the X-ray generator according to the invention.
  • the anode plate of the rotary anode must have cooled down along the focal path, which meets in the operation of the electron beam, after one revolution to the initial temperature immediately before the impact of the electron beam; Otherwise, overheating of the anode plate in the region of the focal point occurs very quickly.
  • the wall region of the rotary anode in the region of the focal path is made as thin as possible while maintaining the required mechanical and thermal stability, since the thermal conductivity of the wall region and thus the heat transfer from the focal path to the first coolant is inversely proportional to the wall thickness of this wall region.
  • Particularly preferred here is a wall thickness of 3 mm or less selected.
  • the first coolant is preferably boiled in the region of the focal path, thereby breaking up a stagnant film of the first coolant.
  • Another possibility is to generate turbulence in the first coolant below the focal point.
  • the heat dissipation by the first coolant is improved, but the generation of turbulence causes a great deal Frictional heat, which must be additionally dissipated by the cooling.
  • the generation of frictional heat costs additional drive energy, whereby the achievable speed of the rotary anode is reduced.
  • a boiling of the first coolant is preferable to a generation of turbulence.
  • the first coolant is preferably water.
  • the anode plate contains 80 ml of water.
  • the bearing part is formed with ribs.
  • These ribs serve as cooling fins for increasing the surface of the bearing part to be brought into contact with the first coolant for the purpose of better heat transfer between the first coolant and the bearing part.
  • the ribs serve an advantageous increase in the mechanical strength of the bearing part.
  • the bearing axis is preferably configured hollow-shaft-like. Such a configuration of the bearing axis is easy to produce and allows an advantageous guidance of the second coolant.
  • the bearing axis is preferably formed with ribs in the interior.
  • These ribs are like those on the bearing part in particular provided as cooling fins for increasing the surface area for the purpose of better heat transfer, here between the bearing axis and the second coolant.
  • the ribs can be aligned axially to the bearing axis, whereby preferably a laminar flow is formed in the bearing axis.
  • the bearing axis is formed in the interior with turbulence in the flow of a second coolant generating devices.
  • the above-described ribs in the interior of the bearing axis for. Example, by a tangentially offset arrangement or the like, to generate turbulence in the flow of the second coolant for the purpose of better heat transfer.
  • the interior of the bearing axis instead of ribs can also be designed with other shapes, or inserts can be introduced into the bearing axis, which cause the desired flow conditions.
  • the invention advantageously allows the use of the described X-ray generator for long operating intervals and long exposure times.
  • the X-ray generator according to the invention is therefore preferably used for crystallography, since it allows a very high point performance of the generated X-ray radiation on the irradiated object can be achieved, and for computed tomography, in which numerous X-ray images in rapid succession to create.
  • the X-ray generator according to the invention makes it possible to achieve a fast image sequence with short exposure times.
  • the X-ray generator according to the invention is designed for a large thermal load, in particular the rotary anode, but also the cathode, by the current of the electron beam between the cathode and the rotary anode. For the rotary anode, a very high speed is achievable.
  • the X-ray generator according to the invention comprises a hermetically sealed, vacuum-tight housing for enclosing at least the high-emitting thermal low-temperature cathode, the rotary anode with the anode plate and the bearing part and the electron focusing device.
  • the bearing axis advantageously forms an element of the hermetically sealed, vacuum-tight housing.
  • the hermetically sealed, vacuum-tight housing for example in the form of a sealed-glass flask, a metal housing or the like, provides optimum protection against external influences on the structural elements of the X-ray generator according to the invention.
  • types of Röntgengenerato- ren which are temporarily or permanently connected to maintain a high vacuum in the interior during operation with a vacuum pump
  • impurities could cause damage to the cathode there and thus reduce their electron emission.
  • the said dispenser cathodes are sensitive to contamination by organic substances.
  • the liquid metal described is used.
  • the pump oil used therein could lead to damage because, in addition to other contaminants, for example from the surrounding atmosphere, despite the backpressure of the vacuum could penetrate the inside of the X-ray generator.
  • harmful impurities include a number of metals.
  • copper is harmless, which is why the rotary anode is preferably made of this metal.
  • a vacuum pump requires expensive maintenance.
  • the X-ray generator according to the invention is designed with a temperature monitoring device for measuring and / or monitoring the temperature of the anode plate in the region of the focal path.
  • the temperature monitoring serves to protect the X-ray generator against damage caused by overheating of the anode plate, in particular in the region of the focal track due to the impact of the electron beam during operation. Since, due to the high currents, such overheating of the anode plate during operational irregularities, in particular when the rotational speed of the rotary anode decreases, e.g.
  • the temperature monitoring device is preferably a very fast shutdown of the voltage applied between the rotary anode and cathode DC voltage feasible. Particularly preferably, this shutdown takes place within a millisecond.
  • the temperature monitoring device is designed with a very fast-reacting temperature sensor.
  • the temperature sensor is designed as an infrared sensor for measuring the temperature of the anode plate in the region of the focal path.
  • the infrared sensor enables a very fast, highly effective temperature measurement.
  • the temperature monitoring device is designed, in addition to the said interruption of the electron beam, alternatively or additionally to the down-regulation of the electron beam as soon as the temperature of the focal path exceeds a temperature limit.
  • the operation of the X-ray generator is then not completely interrupted with an undesirable increase in the temperature on the focal path of the rotary anode; rather, a safe, permanent operation can be maintained.
  • the reliability and ease of use of the X-ray generator according to the invention are substantially increased.
  • the latter comprises a rotational speed monitoring device for measuring and / or monitoring the rotational speed of the rotary anode.
  • a speed sensor can preferably be provided a light barrier arrangement through which a passing of in the Rotary anode attached and rotating with their rotation marks, such as slots, is detected.
  • the rotary anode has an at least substantially rotationally symmetrical element with varying magnetic properties along its circumference and is the speed monitoring device with a Hall sensor for detecting the varying magnetic properties and thereby measuring the rotational speed formed the rotary anode.
  • the speed measurement by means of a Hall sensor as a speed sensor is particularly advantageous and feasible with simple means, if according to a further development of the X-ray generator with respect to the axis of rotation at least substantially rotationally symmetric element with varying magnetic properties along its circumference part of a rotor of a drive motor of the rotary anode.
  • the rotor of the drive motor of the rotary anode is preferably designed with an iron-coated, tubular rotor body made of copper rotatably mounted on the bearing axis, in which regions of varying magnetic properties are formed along its circumference by recesses in at least the iron coating.
  • the recesses may be in the form of slots or holes of various possible contours in the iron coating, but also in the underlying copper, e.g. by drilling or milling, but also e.g. be attached by etching.
  • the rotational speed monitoring device is designed to downshift and / or interrupt the electron beam as soon as the rotational speed of the rotary anode falls below a rotational speed limit value.
  • the speed monitoring device also preferably serves to protect the X-ray generator from damage due to overheating of the anode plate, in particular in the region of the focal path due to the impact of the electron beam during operation.
  • their first task is to keep the rotational speed of the rotary anode at a constant setpoint, which ensures safe operation without risk of thermal and / or mechanical overload.
  • interruption of the electron beam upon occurrence of irregularities in the rotation of the rotary anode is caused.
  • a very fast shutdown of the voltage applied between rotary anode and cathode DC voltage feasible is a very fast shutdown of the voltage applied between rotary anode and cathode DC voltage feasible. Particularly preferably, this shutdown takes place again within a millisecond.
  • the rotation speed monitoring means is alternatively or additionally adapted to continuously lower the current of the electron beam, i. the cathode current as soon as the rotational speed of the rotary anode falls below the speed limit.
  • the operation of the X-ray generator is then not completely interrupted in an undesirable decrease in the rotational speed of the rotary anode; Rather, a safe, permanent operation can be maintained here, whereby the reliability and ease of use of the X-ray generator according to the invention are substantially increased.
  • a dependence of the speed control of the regulation of the cathode current can be provided for the X-ray generator according to the invention, i. that for a given cathode current, a certain speed is automatically adjusted so that a safe, damage-free operation is ensured.
  • the X-ray generator comprises a control device for controlling the rotational speed of the rotary anode in dependence on the current of the electron beam and the temperature of the focal path and / or for controlling the current of the electron beam in dependence on the rotational speed of the rotary anode and the temperature of the focal path.
  • the control device can perform a speed control as a function of the measured temperature of the focal path for a predefinable cathode current, combined with an emergency shutdown of the cathode current as soon as the temperature of the focal path exceeds the temperature limit.
  • the cathode current can also be controlled in a separate control device to a predetermined current setpoint, and said control device assumes a speed control as a function of the measured temperature of the focal path for a measured actual value of the cathode current.
  • control device can make a regulation of the cathode current as a function of the measured temperature of the focal path for a predefinable rotational speed of the rotary anode, combined with an emergency shutdown of the cathode current, as soon as the temperature of the focal path exceeds the temperature limit.
  • the rotational speed of the rotary anode can also be controlled in a separate control device to a predefinable speed setpoint, and said control device adjusts the cathode current as a function of the measured temperature of the focal path for a measured actual value of the rotational speed of the rotary anode, in turn combined with the Emergency shutdown of the cathode current as soon as the temperature of the focal track exceeds the temperature limit.
  • the electron focusing device is arranged to focus the electron beam onto an at least substantially rectangular focal spot on the focal track.
  • the electron focusing device is arranged to focus the electron beam on a rectangular elongated focal spot. Since the radiant power of the x-ray emanating from the focal spot is proportional to the length but only proportional to the square root of the width of the focal spot, the radiant power of the x-ray emanating from the focal spot is effectively increased.
  • the at least substantially parallel X-ray beam can be emitted from the at least substantially parallel X-ray beam at a predetermined radiation angle to the surface of the anode plate at the focal spot, whereby the radiation angle to the ratio of length to width of the focal spot is dimensioned in that the at least nearly parallel X-ray beam has an at least approximately square cross-section.
  • the higher radiation power of the X-ray radiation emanating from the focal spot can be summarized in an advantageously universally usable X-ray beam.
  • the ratio of length to width of the focal spot set at least almost to the value 10 and the radiation angle to at least almost a value of 6 °. Since the sine of an angle of 6 ° is approximately 0.1, this dimensioning can be used to increase a factor of ten. te radiate radiation power in an X-ray beam with a square cross-section.
  • the X-ray generator according to the invention has at least one diaphragm arrangement for shaping the at least approximately parallel X-ray beam.
  • a diaphragm arrangement can have two apertures with a square passage for the X-ray radiation which are arranged at a distance from one another in the direction of the beam path of the X-ray beam.
  • an arrangement explained in more detail below may be provided.
  • the X-ray generator according to the invention has at least one focusing device for focusing the at least approximately parallel X-ray beam onto a focal point.
  • the focusing of the at least nearly parallel X-ray beam is performed by mirrors which reflect the X-radiation, whereby a more accurate focusing and a reduced loss of radiation power of the X-radiation can be achieved.
  • each of the at least one focusing device comprises at least one mirror pair of two mirrors for each bundling direction aligned transversely to the beam path, the mirrors having a curved contour in one direction and this contour being formed by a logarithmic spiral, and the poles of the logarithmic spirals of the two mirrors of each pair of mirrors coincide.
  • a logarithmic spiral means a spiral in which the distance from this center point changes by the same factor with each revolution about its center, which is also called the center or pole of the logarithmic spiral. Every straight line through the center always intersects the logarithmic spiral at the same angle. Because of this property, the logarithmic spiral is also called an equiangular spiral. This property uniquely characterizes the logarithmic spiral.
  • the at least nearly parallel X-ray beam is focused at the center of the logarithmic spirals.
  • the focus of the X-ray beam and thus the radiation power at a focal point allows, for example, when using the X-ray generator according to the invention for crystallography a high power concentration on a very small space on or in the object to be irradiated.
  • a particularly high power concentration is obtained by arranging two mirror pairs in succession into the beam path of the at least nearly parallel X-ray bundle for at least two mutually perpendicularly aligned bundle directions and selecting the curvatures of the contours of the mirrors of the different mirror pairs differently are that a focusing of the X-ray beam in the different focusing directions to the same focal point occurs.
  • a particularly high radiation power of the X-ray radiation occurs in this focal point.
  • a comparable, further arrangement of mirrors with contours curved in accordance with a logarithmic spiral can, in a modification of the described embodiment of the inventive X-ray generator, instead of the at least one diaphragm arrangement, be used to form the at least nearly parallel X-ray beam.
  • a further arrangement of mirrors may have two further pairs of mirrors arranged in succession in the direction of the beam path of the X-ray beam, with which the X-ray radiation, which can be assumed to be simplified starting from a point source, can be formed into a substantially parallel X-ray beam.
  • the beam path of the X-ray radiation is reversed as in the above-described at least one focusing device, i. the substantially point source of the X-ray radiation is arranged in the center of the curvatures of the further mirror pairs in the form of logarithmic spirals.
  • a DC voltage source which can be set to a constant voltage value is connected between the rotary anode and the high-temperature, low-temperature, thermal-emitting cathode.
  • This DC voltage source which is designed to supply an acceleration voltage for the charge carriers in the electron beam from the cathode to the anode, can therefore be of simple construction.
  • the DC voltage source is formed with a current regulating stage for regulating the current of the electron beam via a regulation of a current flowing to the cathode, ie of the cathode current, to a constant presettable value. Since a required focusing of the electron beam on the focal path on the anode plate depends on the current intensity of the cathode current and thus that of the electron beam, such is one Control advantageous to produce a fixed focal spot of the electron beam along the focal path on the anode. With this measure, the reliability of the operation of the X-ray generator according to the invention is increased.
  • FIG. 2 shows a first modification of the example of the X-ray generator according to the invention according to FIG. 1,
  • FIG. 3 shows a second modification of the example of the X-ray generator according to the invention according to FIG. 1,
  • FIG. 4 shows a third modification of the example of the X-ray generator according to the invention according to FIG. 1,
  • FIG. 5 shows a fourth modification of the example of the X-ray generator according to the invention according to FIG. 1,
  • FIG. 6 shows a schematic representation of an example of an at least substantially rectangular focal spot and the generation of an at least approximately parallel X-ray beam
  • Figure 7 shows an embodiment of a focusing device for focusing the at least nearly parallel X-ray beam to a focal point.
  • the X-ray generator 100 includes a high-temperature, low-temperature, low-temperature cathode 101 for discharging an electron beam 102.
  • the high-temperature low-temperature thermal cathode 101 is formed as a large-area coated so-called dispenser cathode.
  • This cathode is particularly advantageously coated with barium oxide.
  • a coating of a barium-scandium alloy is applied instead.
  • the cathode 101 is impregnated, ie impregnated, with a coating of an alloy of platinum group metals. ram cathode designed.
  • Such trained cathodes show even at operating temperatures of about 900 ° C a very good electron emission and are thus able to provide a high cathode current at material-saving and energy-saving operation to keep the dissipated heat loss low and to achieve a long service life.
  • the X-ray generator according to the invention can advantageously be used with high continuous power.
  • the cathode 101 is connected via two heating terminals 103, 104 to a heating current source 105 for supplying a heating current for the heating of the cathode 101.
  • the Schustromario 105 is designed for adjusting or regulating the heating current, preferably such that a stable operating temperature of the cathode is set.
  • the Schustromario is further advantageous for lowering and / or interrupting the heating current and thus the electron beam 102 controllable, as will be explained in more detail below.
  • the x-ray generator 100 furthermore has a rotary anode 107 comprising an anode plate 106.
  • An electron focusing device 108 is disposed in the path of the electron beam 102 between the cathode 101 and the rotating anode 107 and serves to focus the electron beam 102 on a focal path 109 along a surface of the anode plate 106.
  • the electron focusing device 108 in the embodiment Fig. 1 as a simple capacitor arrangement with two can be acted upon with a deflection voltage plate electrodes 110, 111 and one associated Ablenkpressivesan gleich 112, 113 roughly schematically.
  • deflection devices e.g. Even those that use to deflect the electron beam 102 of a magnetic field possible.
  • the rotary anode 107 is rotatably guided in a bearing device 114 about a rotation axis 115.
  • the focal path 109 is rotationally symmetrical to the axis of rotation 115, so that upon rotation of the rotary anode 107 in operation, the focusing of the electron beam 102 from the rotational angle of the rotary anode 107, ie their instantaneous position, is independent.
  • the focal path 109 extends on an at least substantially cylindrical boundary 117 on the outer circumference of the anode plate 106.
  • the boundary 117 is adjacent in the axial direction to a substantially disk-shaped wall region 118, 119, which in turn is connected to a bearing part 120 which is rotationally symmetrical with respect to the rotation axis 115.
  • the essentially disk-shaped wall regions 118, 119 together with the at least largely cylindrical boundary 117 form a connection between the focal path 109 and the bearing part 120.
  • the at least substantially cylindrical boundary 117 which is essentially disc-shaped wall regions 118, 119 and the bearing part 120 a gas-tight enclosed cavity 121 is formed which, on the one hand, adjoins the focal path 109 and, on the other hand, the bearing part 120.
  • the anode plate 106 is at least in the region of the at least substantially cylindrical boundary 117, on which the focal path 109 extends, and there formed at least on the surface to be hit by the electron beam 102 with copper.
  • the rotary anode 107 but in particular the anode plate 106 and the bearing part 120, made of metal for reasons of mechanical and thermal strength and to ensure good electrical conductivity.
  • the bearing device 114 has between the rotating anode 107 connected to the bearing part 120 which is rotatably guided about the rotation axis 115 and rotates in operation with the rotary anode 107 and thus the anode plate 106, and a bearing axis fixed to the other 122 a liquid metal slide bearing 123.
  • This is advantageous with spiral grooves on mutually facing sliding surfaces of the bearing part 120 and the bearing axis 122 and between the bearing part 120 and the bearing gerachs 122 arranged thin layer made of an alloy of gallium, indium and tin as a lubricant.
  • This metal alloy has a low vapor pressure and a high thermal conductivity and allows a simple structural design of the bearing device 114.
  • the low vapor pressure, a gassing of the lubricant is avoided even under high vacuum, and the good heat conduction allows rapid and efficient transfer of heat energy from the anode plate 106th on the bearing axis 122, which benefits the device described below for cooling the focal path 109 benefits.
  • a first coolant is introduced, which is used for cooling the focal path 109 on the anode plate 106 according to the outlined initially He-pipe principle.
  • the first coolant in the cavity 121 evaporates on the inner surface 124 of the at least substantially cylindrical boundary 117 heated by the impact of the electrons of the electron beam 102 on the fuel surface 109.
  • the wall thickness of the Wall region of the anode plate 106 in the region of the boundary 117 made as thin as this is still possible while maintaining the required mechanical stability.
  • this wall thickness is 3 mm or less.
  • the vaporized first coolant reaches the bearing part 120, condenses there and releases its heat of condensation to the bearing part 120.
  • this is formed with ribs 125, which serve to increase the surface of the bearing part 120 that comes into contact with the coolant and in addition to its mechanical stabilization.
  • the ribs 125 are sketched with a straight top edge and axially aligned; they may also have a different shape and orientation. Due to the rotation of the rotary anode 107 centrifugal forces convey the condensed first coolant to the inner surface 124 of the at least substantially cylindrical boundary 117 back.
  • the closed in this way heat cycle of the first coolant according to the heat pipe principle is symbolized in Fig. 1 by arrows 126.
  • the cavity 121 is thus set up to boil the first coolant in the region of the focal path 109 and to condense the first coolant in the region of the bearing part 120.
  • the bearing axis 122 of the exemplary embodiment of the X-ray generator 100 according to the invention is hollow-wave-like for a flow symbolized by arrows 127 through a second coolant.
  • the liquid metal sliding bearing 123 forms a heat conducting element for transferring the heat energy between the bearing part 120 and the bearing axis 122, ie between the first coolant and the second coolant.
  • the bearing shaft 122 is internally formed with ribs 128, ie, cooling fins.
  • the ribs 128 may be axially aligned with the bearing axis 122, whereby a laminar flow of the second coolant in the bearing axis 122 is preferably formed, or they may in another embodiment, not shown, for example by tangentially staggered arrangement or the like, for generating turbulence in the stream the second coolant be set up for better heat transfer.
  • the interior of the bearing axis 122 may be configured instead of ribs 128 or in addition to these also with other shapes, or inserts may be introduced into the bearing shaft 122, which cause the desired flow conditions.
  • a very efficient Kondensationskühlan extract is provided in the manner described above, which is formed with the present between the focal path 109 and the bearing part 120 of the rotary anode 107 first coolant and the configuration of the bearing axis 122 for a flow through the second coolant, wherein the liquid metal sliding bearing 123 forms a thermally conductive element for transferring the heat energy between the first coolant and the second coolant.
  • the above-described structural elements of the X-ray generator 100 namely the cathode 101, the rotary anode 107 and the electron focusing device 108, are enclosed by a hermetically sealed, vacuum-tight housing 129.
  • the bearing axle 122 forms an element of this hermetically sealed, vacuum-tight housing 129. This avoids moving housing passages.
  • the hermetic completion of the housing 129 from the environment and the deliberate abandonment of any kind of opening, the gases or other contaminants could allow access to the interior of the housing 129 and thus to the above-described structural elements of the X-ray generator 100, any impairment of the operation of the Röntgenge - nerators 100 excluded by such impurities from the outset.
  • the housing 129 preferably also serves to shield unwanted X-radiation exiting.
  • the X-ray generator 100 furthermore has a temperature monitoring device 130 for measuring and / or monitoring the temperature of the anode plate 106 in the region of the focal path 109.
  • a temperature monitor 130 for measuring and / or monitoring the temperature of the anode plate 106 in the region of the focal path 109.
  • the temperature monitoring device 130 is formed with an infrared sensor 131 for measuring the temperature of the anode plate 106 in the region of the focal path 109.
  • the infrared sensor 131 is characterized by a very fast measurement, i.
  • the infrared sensor 131 is preferably arranged within the housing 129 for a precise and rapid measurement and is electrically connected to the temperature monitoring device 130 via a measuring line 132, which is guided through the housing 129 by means of a line feedthrough 133. Via the measuring line 132, a temperature measurement signal is transmitted to the temperature monitoring device 130.
  • line feedthroughs 133 are also provided for carrying out the heating connections 103, 104 and the deflection voltage connections 112, 113 through the housing 129.
  • the cable bushings 133 are formed electrically insulating.
  • the temperature monitoring device 130 is advantageously designed to shut down and / or to interrupt the electron beam 102 as soon as the temperature of the focal track 109 exceeds a predetermined temperature limit.
  • the temperature monitoring device 130 is connected via a control line 134 to a DC voltage source 135.
  • This DC power source 135 is connected between the rotating anode 106 and the high-temperature low-temperature thermal-emitting cathode 101, and serves to provide a high voltage between the cathode 101 and the rotating anode 107 for accelerating the electrons of the electron beam 102.
  • a negative pole 136 is the DC voltage source 135 is connected to a high voltage terminal 138 of the cathode 101 via a first high voltage line 137 routed through one of the line feedthroughs 133.
  • a positive pole 139 of the DC voltage source 135 is connected to the bearing axis 122 via a second high-voltage line 141.
  • the positive pole 139 may also be connected to the vacuum-tight housing 129 via the second high-voltage line 141 and connected to the bearing axis 122. Housing 129 and bearing axis 122 are preferably always electrically connected to each other and connected to ground potential 140 to limit hazards due to the high voltage and insulation problems to a minimum.
  • the DC voltage source 135 is advantageously adjustable to a constant voltage value and thus supplies a constant acceleration voltage between the cathode 101 and the rotary anode 107.
  • the DC voltage source 135 is particularly preferably designed with a current regulating stage for regulating the current of the electron beam 102 via a Control of the cathode 101 via the first high voltage line 137 incoming stream, ie the cathode current of the X-ray generator 100, to a constant predetermined value. As described above, this control facilitates the focusing of the electron beam 102 on a defined focal point 116.
  • a control of the cathode current provides increased security against thermal overload of the rotary anode 107.
  • the temperature monitor 130 is configured to shut down and / or interrupt the electron beam 102 as soon as the temperature of the focal path 109 exceeds a predetermined temperature limit.
  • a control signal triggering this shutdown or interruption is conducted by the temperature monitoring device 130 via the control line 134 to the DC voltage source 135.
  • the temperature monitoring device 130 is optionally configured such that either a continuous downward regulation of the electron beam 102 via a continuous downward regulation of the cathode current and thus a compensation of the increase in the temperature of the focal path 109 down to the predetermined temperature limit and holding this temperature value is carried out, or that the electron beam is switched off quickly via a preferably rapid, abrupt interruption of the cathode current, in order to avoid damage as fast as possible cooling of the focal path 109 to achieve.
  • a second control line 142 provided by the temperature monitoring device 130 to the Schustromquelle 105 leads.
  • a second control signal which can be supplied by the temperature monitoring device 130 via the second control line 142 to the heating current source 105 serves to control the heating current source 105 in such a way that, when an impermissibly high temperature of the focal path 109 occurs above the predetermined temperature limit value, that of the heating current source 105 via the heating connections 103, 104 supplied to the cathode 101 heating current optionally continuously down-regulated or quickly interrupted, ie is switched off.
  • the X-ray generator 100 further comprises a rotational speed monitoring device 143 for measuring and / or monitoring the rotational speed of the rotary anode 107.
  • the rotational speed monitoring device 143 is connected to a rotational speed sensor 145 via a second measuring line 144.
  • the second measuring line 144 is configured to transmit a rotational speed measuring signal representing the rotational speed of the rotary anode 107 from the rotational speed sensor 145 to the rotational speed monitoring device 143.
  • the speed sensor 145 may be formed with a light barrier arrangement, through which a passing of mounted in the rotary anode 107 and rotating with the rotation markings, such as slots, is detected.
  • the rotary anode 107 has an element 146 which is at least substantially rotationally symmetrical with respect to the axis of rotation 115 and has magnetic properties varying along its circumference.
  • the rotation speed sensor 145 is configured as a hall sensor for detecting the varying magnetic characteristics and thereby measuring the rotation speed of the rotation anode 107.
  • the rotational speed sensor ie, the Hall sensor 145
  • the Hall sensor 145 is preferably arranged in the interior of the housing 129 close to the rotationally symmetrical element 146, and the second measuring line 144 is preceded by one of the cable bushings 133. Led outside the housing 129 arranged speed monitoring device 143.
  • the element 146 which is at least substantially rotationally symmetrical with respect to the rotation axis 115 and has magnetic properties varying along its circumference, is part of a rotor 147 of a drive motor of the rotary anode 107.
  • the rotor 147 of the drive motor of the rotary anode 107 according to FIG. 1 is particularly advantageous formed with a rotatably mounted on the bearing axis, iron-coated tubular rotor body 148 made of copper, in which along its circumference areas of varying magnetic properties are formed, either by different bias or preferably by recesses at least in the iron coating 149.
  • the varying generates magnetic properties of the at least largely rotationally symmetric element 146;
  • the at least substantially rotationally symmetrical element 146 forms part of the rotor 147.
  • the liquid metal sliding bearing 123 also extends between the bearing shaft 122 and the rotor 147, and the bearing part 120 and the rotor body 148 are made in one piece formed a copper tube. This results in a simple, precise, lightweight and robust construction.
  • the rotational speed monitoring device 143 of the X-ray generator 100 according to FIG. 1 is designed to down-regulate and / or interrupt the electron beam 102 in a manner corresponding to the temperature monitoring device 130.
  • the rotational speed monitoring device 143 is connected via a third control line 150 to the DC voltage source 135 for supplying a third control signal from the rotational speed monitoring device 143 to the DC voltage source 135.
  • cathode current is optionally continuously downshifted as soon as the rotational speed of the rotary anode 107 falls below a speed limit and thus the electron beam 102 would act too long on one and the same location of the focal path 109 so that they are there would heat excessively, or the cathode current is rapidly switched off via the voltage applied between the rotary anode 107 and the cathode 101 DC voltage and thus the electron beam 102 is interrupted abruptly.
  • this fast shutdown as well as the triggered by the temperature monitoring device 130 fast shutdown takes place within a millisecond.
  • the heating current source 105 is furthermore optionally or additionally connected via a fourth control line 151 to the heating current source 105 for supplying a fourth control signal from the rotational speed monitoring device 143 to the heating current source 105.
  • the fourth control signal fed by the Schustromquelle 105 heating current is either continuously downshifted as soon as the rotational speed of the rotary anode 107 falls below a speed limit, or the heating current is switched off quickly and thus the electron beam 102 optionally continuously down regulated or quickly interrupted.
  • a stator 152 which is only roughly schematically indicated in FIG. 1, is provided.
  • the rotor 147 within the housing 129, the stator 152 but disposed outside of the housing 129.
  • This is e.g. associated with the advantage that the stator 152 is more easily accessible for repairs and that the materials used for its construction, in particular organic insulating materials, can enter any impurities in the housing 129.
  • the wall of the housing 129 in the space region of the gap between the rotor 147 and the stator 152 is formed of non-magnetic material.
  • the x-ray generator 100 according to FIG. 1 furthermore has a control device 153.
  • the control device 153 is optionally configured to control the rotational speed of the rotary anode 107 in dependence on the current of the electron beam 102 and the temperature of the focal path 109 and / or for controlling the current of the electron beam 102 in dependence on the rotational speed of the rotary anode 107 and the temperature of the focal path 109 ,
  • the control device 153 is connected to the DC voltage source 135 via a first connecting line 154 and to the temperature monitoring device 130 via a second connecting line 155.
  • the first connection line 154 is set up for transmitting a current measurement signal representing the current intensity of the cathode current, which is output from the DC voltage source 135, to the control device 153.
  • the second connection line 155 is configured to transmit the temperature measurement signal from the infrared sensor 131 via the temperature monitoring device 130 to the control device 153.
  • a drive control signal is generated in the control device 153, through which the drive motor of the rotary anode 107th is controlled.
  • the drive control signal is generated in the control device 153, through which the drive motor of the rotary anode 107th is controlled.
  • at least one current in the stator 152 of the drive motor of the rotary anode 107 is controlled by the drive control signal.
  • the control device 153 is furthermore connected to the DC voltage source 135 via the first connecting line 154 and to the temperature monitoring device 130 via the second connecting line 155.
  • the second connection line 155 is further configured to transmit the temperature measurement signal from the infrared sensor 131 to the controller 153 via the temperature monitor 130.
  • a cathode current control signal is formed.
  • the cathode current control signal is provided for controlling the cathode current of the x-ray generator 100 and thus the current of the electron beam 102.
  • the dc voltage source 135 is advantageously designed as described with a current regulation stage.
  • controlling the rotational speed of the rotary anode 107 in response to the current of the electron beam 102 and the temperature of the focal path 109 is for controlling the current of the electron beam 102 in response to the rotational speed of the rotary anode 107 and the temperature of the focal path 109, the first connecting line 154th now arranged to transmit the cathode current control signal from the controller 153 to the DC voltage source 135.
  • control device 153 may advantageously be designed to reduce or interrupt the current of the electron beam 102 when the focal track 109 overheats. This is done in the example shown in FIG. 1 via a fifth and a sixth control line 157 and 158, respectively, which are guided by the control device 153 to the DC voltage source 135 or to the heating current source 105.
  • the fifth control line 157 can also be used for transmitting the cathode current control signal from the control device 153 to the DC voltage source 135, or the cathode current control signal can preferably also be used to control the shutdown or interruption of the cathode current.
  • the first connection line 154 is then exclusively directed to transmit the current measurement signal to the controller and does not have to be switched between different operating cases.
  • control circuit 153 shows various embodiments of the function of the control circuit 153, through which an advantageous connection of the control of the rotational speed of the rotary anode 107 and the cathode current with the temperature control or the temperature monitoring is obtained, which is carried out with some different dependencies shown by way of example.
  • the connections of the control circuit 153 with other elements of the X-ray generator 100 for the sake of simplicity only partially shown or indicated.
  • the control device is designed to execute a speed control as a function of the measured temperature of the focal path 109 for a predefinable cathode current, combined with an emergency shutdown of the cathode current, as soon as the temperature of the focal path 109 exceeds the temperature limit.
  • the control circuit 153 the temperature measurement signal via the second connecting line 155 and the speed measurement signal via the third connecting line 156 is supplied.
  • the drive control signal for controlling at least one current in the stator 152 of the drive motor of the rotary anode 107 is formed therefrom and the at least one current supplied to the stator 152 connected to the control device 153.
  • an emergency shutdown signal is generated in the control device 153 and thus the DC voltage source 135 and optionally also the sixth control line 158 control the heating current source 105 for regulating or interrupting the electron current 102 via the fifth control line 157.
  • the cathode current and thus the electron current 102 can be regulated in a separate regulation device 159 to a predefinable current setpoint, which is supplied to the regulation device 159 via a current setpoint connection 160.
  • the current measuring signal from the DC voltage source 135 is also fed to the regulating device 159 via the first connecting line 154.
  • a current adjustment signal formed from a comparison of the current setpoint value with the current measurement signal in the control device 159 is conducted via a current control signal line 161 from the control device 159 to the DC voltage source 135 for controlling the cathode current.
  • the current measurement signal from the DC voltage source 135 is also supplied to the control device 153.
  • the control device 153 further receives the temperature measurement signal via the second connection line 155 and the speed measurement signal via the third connection line 156 supplied.
  • the control device 153 generates therefrom the drive control signal and thus adopts a rotational speed control of the drive motor of the rotary anode 107 as a function of the measured temperature of the focal path 109 for a measured actual value of the cathode current via a control of at least one current in the stator 152 of the drive motor of the rotary anode 107.
  • the control device 153 performs a control of the cathode current as a function of the measured temperature of the focal path 109 for a predefinable rotational speed of the rotary anode 107, combined with an emergency shutdown of the cathode current as soon as the temperature of the focal path 109 reaches the temperature limit exceeds.
  • the control circuit 153 is supplied via a speed setpoint connection 162, a speed setpoint and the second connection line 155, the temperature measurement signal. Via the fifth control line 157, the control of the DC voltage source 135 takes place.
  • the modification of FIG. 5 shows a control of the rotational speed of the rotary anode 107 to a predetermined speed setpoint in a separate speed control device 163.
  • the control device 153 takes a control of the cathode current as a function of the measured temperature of the focal path 109 for a measured actual value the rotational speed of the rotary anode 107, in turn combined with the emergency shutdown of the cathode current, as soon as the temperature of the focal path 109 exceeds the temperature limit.
  • the rotational speed control device 163 is supplied with the rotational speed measuring signal via the second measuring line 144 and with the rotational speed desired value via the rotational speed desired value connection 162.
  • the drive control signal is now generated therefrom and thus a speed control of the drive motor of the rotary anode 107 to the speed setpoint via a control of at least one current in the stator 152 of the drive motor of the rotary anode 107 made.
  • the speed control device 163 of the control device 153 via the third connecting line 156 the speed measurement signal and further supplied via the second connecting line 155, the temperature measurement signal.
  • the control device 153 adjusts a control of the cathode current as a function of the measured rotational speed of the rotary anode 107 and the measured temperature of the focal path 109, combined with an emergency shutdown of the cathode current as soon as the temperature of the focal path 109 exceeds the temperature limit and / or the speed of the Rotary anode 107 falls below a speed limit.
  • the control of the DC voltage source 135 takes place here again via the fifth control line 157th FIG.
  • FIG. 6 shows a schematic representation of an example of an at least substantially rectangular focal point 116 and the generation of an at least nearly parallel X-ray beam 164, as is the result of the impact of the electron beam 102 of the electron beam focused on the focal spot 116 from the electron focusing device 108 Anodenteller 106 is emitted.
  • the at least nearly parallel X-ray beam 164 is thereby formed by a diaphragm arrangement 165 with two mutually arranged in a radiation emanating from the focal spot 116 Abstrahlungscardi of the X-ray beam 164 164 167 formed from the total of the anode plate 106 at the location of the focal spot 109 emitted X-rays, ie from the entirety of the X-radiation emitted by the anode plate 106 in the region of the focal spot 109 through passages formed in the apertured diaphragms 166, 167, ie areas permeable to X-ray radiation, such as cutouts or openings, but also radiation windows.
  • Such a passage 173 for the X-ray beam 164 is also formed in the housing 129 of the X-ray generator 100, wherein this passage 173 is designed as a radiation-permeable but vacuum-tight window in the housing 129.
  • the focal spot 116 has a length 168 transverse to the direction of movement 170 of the anode plate 106 or the focal path 109, which corresponds to a certain multiple of a width 169 of the focal spot 116 in the direction of movement 170 of the anode plate 106 and the focal path 109.
  • the radiation angle 171 is the ratio of length 168 to width 169 of the focal spot 116 advantageously dimensioned such that the at least nearly parallel X-ray beam 164 has an at least approximately square cross-section, ie the width 169 of the focal spot 116 and thus of the X-ray beam 164 is at least almost equal to a height 172 of the X-ray beam 164.
  • the passages in the pinholes 166, 167 are then also at least almost square.
  • the focal spot 116 has a length 168 transverse to the direction of movement 170 of the anode plate 106 or the focal path 109, which is ten times the width 169 of the focal spot 116 in the direction of movement 170 of the anode plate 106 or the focal path 109. speaks.
  • the radiation angle 171 is suitably fixed to at least approximately 6 °.
  • the length 168 of the focal spot 116 is about 1 mm, and the width 169 is 0.1 mm. From this, an X-ray beam 164 having a cross section of 0.1 mm * 0.1 mm is obtained.
  • FIG. 7 shows, in a roughly schematic, perspective illustration, an exemplary embodiment of a focusing device 174 for focusing the at least nearly parallel X-ray beam 164 onto a focal point 175.
  • the focusing device 174 is preferably combined with the X-ray generator 100 in a common assembly, whereby an X-ray generator 100 is obtained which is to deliver a very high radiant power of x-ray radiation at focal point 175, ie a very high spatial power concentration is set up.
  • the focusing of the X-ray beam, i. the radiant power, at focal point 175, a high power concentration in a very small space, especially on an object to be irradiated, e.g. when using the X-ray generator 100 according to the invention for crystallography is advantageously used.
  • the focusing device 174 is preferably arranged directly adjacent to the passage 173 of the housing 129.
  • the focusing device 174 of the exemplary embodiment according to FIG. 7 comprises a first and a second pair of mirrors 176, 177 made up of two mirrors 178, 179 and 180, 181, one each of the pairs of mirrors 176, 177 for each one of two transverse to the beam path 184 or 174 185 of the at least nearly parallel X-ray beam 164 aligned bundling directions 182, 183 is provided.
  • the beam path of the at least approximately parallel x-ray beam 164, as it passes through the diaphragm arrangement 165 is designated by the reference numeral 184.
  • the reference numeral 185 denotes a center axis of the beam path of the X-ray beam 164 between the first pair of mirrors 176 and the second mirror pair 177.
  • the mirrors 178, 179 and 180, 181 are made of the X-ray radiation highly reflective material.
  • the pairs of mirrors 176, 177 and thus the bundling directions 182, 183 are drawn in such a way that a first 182 of the two directions of bunching 182, 183 is arranged at least substantially at right angles to the second direction of bunching 183.
  • Bundling of the at least nearly parallel X-ray beam 164 takes place in the first mirror pair 176 in the first direction of collimation 182 and in the second
  • the mirrors 178, 179 and 180, 181 each have a curved contour in one direction and this contour is formed by a logarithmic spiral, the poles of the logarithmic spirals the two mirrors 178, 179 and 180, respectively,
  • the at least nearly parallel x-ray beam 164 is focused at the center of the logarithmic spirals of the mirrors 178, 179 and 180, 181 of each of the mirror pairs 176 and 177, respectively.
  • the two pairs of mirrors 176 and 177, respectively, for the two convergent directions 182 and 183, one behind the other, are placed in the beam path 184 or 185 of the at least nearly parallel X-ray beam 164, i. the first mirror pair 176 for the first convergence direction
  • the X-ray beam 164 is focused in the different focusing directions 182 or 183 onto the same focal point 175.
  • the mirrors 178, 179 of the first pair of mirrors 176 are preferably curved exclusively in a plane spanned by the first collimating direction 182 and the beam path 184 of the X-ray beam 164 in front of the first pair of mirrors 176, the logarithmic spiral of the curvature in question lies in this plane, whereas the mirrors 178, 179 perpendicular to this plane have no curvature.
  • the mirrors 180, 181 of the second pair of mirrors 177 are preferably curved exclusively in a plane spanned by the second direction of collimation 183 and the beam path 185 of the X-ray beam 164 between the first mirror pair 176 and the second mirror pair 177 and have no curvature perpendicular to this plane on.
  • one of the further described focusing devices 174 is also advantageous Arrangement of mirrors with a logarithmic spiral curved contours can be used, which can take the place of the diaphragm assembly 165 for forming the at least nearly parallel X-ray beam 164.
  • a further arrangement of mirrors may have two further pairs of mirrors arranged in succession in the direction of the beam path of the X-ray beam, with which the X-ray radiation, which can be assumed to be simplified starting from a point source, can be formed into a substantially parallel X-ray beam.
  • the focal spot 109 is preferably to be correspondingly shaped by an adapted focusing of the electron beam 102, for example substantially circular disk-shaped.
  • the beam path of the X-ray radiation runs in the opposite direction as in the focusing device 174 described above, ie the substantially punctiform source of X-radiation is arranged in the center of the curvatures of the further mirror pairs in the form of logarithmic spirals.
  • Second control line (for second control signal)
  • Second measuring line (for speed measuring signal)
  • First connection line (for current measurement signal or for cathode current control signal)
  • Second connecting line (for temperature measuring signal)
  • Speed reference port (for speed reference)

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Abstract

L'invention concerne un générateur de rayons X (100) conçu de manière compacte à l'aide de moyens simples et adapté à émettre une puissance de rayonnement très élevée, y compris pendant des intervalles de temps très longs. Ledit générateur contient une cathode thermique à basse température (101) à forte émission servant à émettre un faisceau d'électrons (102), une anode tournante (107) qui comprend un disque d'anode (106) et qui est guidée en rotation autour d'un axe de rotation (115) dans une unité support (114) qui comprend un palier lisse en métal liquide entre une partie de support (120) reliée à l'anode tournante et un axe de support (122), un dispositif de focalisation de faisceau d'électrons (108) servant à focaliser le faisceau d'électrons sur une couronne focale (109) le long d'une surface du disque d'anode et un système de refroidissement par condensation comportant un premier réfrigérant situé entre la couronne focale et la partie de support de l'anode tournante et l'axe de support étant conçu pour être traversé par un deuxième réfrigérant, le premier réfrigérant étant entouré de manière étanche au gaz par une liaison structurale formée entre la couronne focale et la partie de support au moins par le disque d'anode, et le palier lisse en métal liquide formant un élément thermoconducteur servant à transférer l'énergie calorifique entre le premier et le deuxième réfrigérant.
EP15732170.4A 2014-05-28 2015-05-28 Générateur de rayons x Withdrawn EP3149760A1 (fr)

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DE102014107576.5A DE102014107576A1 (de) 2014-05-28 2014-05-28 Röntgengenerator
PCT/EP2015/061790 WO2015181269A1 (fr) 2014-05-28 2015-05-28 Générateur de rayons x

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DE202014011302U1 (de) 2019-02-25
DE102014107576A1 (de) 2015-12-03

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