Siemens Aktiengesellschaft

Kernforschungsanlage Julich Gesellschaft MIT Beschrankter Haftung

Rudolf Friedel

Ernst Geldner

Johan K Fremerey

Roland Schmidt

Hans Ebersberger

Werner Mueller

Karl Boden

Herbert Bittl

Klaus Haberrecker

Friedrich Gudden

Henrik Krogmann

Kurt Dietz

George Comsa

Gunther Appelt

An x-ray tube, in addition to an anode and a cathode arrangement, has first and second electrodes that are located in an evacuated housing provided with a beam exit window. The anode and the first electrode are at potentials that are positive in comparison to the potentials of the cathode arrangement and the second electrode. Further, the first and the second electrode are arranged lying opposite one another such that secondary electrons emanating from the anode must pass through the space located between the first and the second electrode in order to proceed to the beam exit window. These secondary electrons are thus substantially all prevented from reaching the beam exit window, thereby avoiding excessive heating of the beam exit window.

X-ray tube

In exemplary embodiments, the anode is driven by an induction motor, between the stator and rotor of which the wall of the vacuum envelope of the tube is disposed. To reduce the overall length and the lever actions of the weight of the anode which act on the bearing which are disadvantageous in this construction, the disclosure provides an annular anode which is disposed in the same plane with the drive rotor. The rotor and stator can here be surrounded by the ring of the anode or they can be secured externally about the latter. X-ray tubes in accordance with the disclosure are particularly suited for use for the purpose of medical x-ray examination.

Rotary anode X-ray tube

In an exemplary embodiment, a metallic shield for the discharge space between the cathode and the anode is connected to a potential which is greater than half the tube voltage and smaller than the entire tube voltage. What is achieved thereby is that backscatter electrons from the focal spot space are withdrawn and the anode load carrying capacity is thereby increased, and that the outside-of-focus component of the radiation is reduced as well. Moreover, a very close-to-focus definition or collimation of the cone of rays is possible. X-ray tubes according to the disclosure are particularly applicable in medical X-ray diagnostics.

X-Ray tube

In an exemplary embodiment, to reduce wear on the bearings of a rotary anode during radiography processes which require a high load of the tube, such as e.g. all types of series techniques, a control of the rotational frequency of the anode is effected according to which the rotational speed of the anode drive motor is increased as a function of increasing thermal load on the anode plate. For this purpose there takes place, in a static frequency changer, an increase of the frequency of the alternating current with which the motor is driven. The motor drive frequency can, for example, be controlled in dependence upon the temperature of the anode plate as sensed by a measuring probe. An inventive drive of rotary anodes is particularly suited for use in the case of X-ray examination apparatus, especially computer tomographs.

Drive for rotary anodes of X-ray tubes

In an exemplary embodiment, a portion of the tube vacuum envelope is disposed between the rotor and stator of the anode drive motor. Taking into account the required high voltage safety, hitherto concessions as to the anode drive had to be made. The disclosure provides an improvement in this regard in that the anode and stator are connected to the same potential until a desired rotational frequency is attained. Only then, subsequent to disconnection of the drive voltage, is the radiography voltage applied for the necessary exposure period. If necessary, subsequently a braking voltage, or again a drive voltage, respectively, can be applied to the stator. Methods and installations in which, in accordance with the disclosure, the drive of the rotary anode is intensified, are, in particular, suited for utilization in medical x-ray diagnostics, mainly computer tomography.

Method and apparatus for the operation of rotary anode X-ray tubes

A rotatable anode for an X-ray tube comprising a body composed of a porous, difficult to melt material enclosed in a sealed fashion within an enveloping layer of a difficult to melt material, characterized by the porous body being of a material having a good thermal conductivity and a good thermal capacity and said porous body having its pores filled with a material having a good thermal conductance and being a good conductor of heat. The porous body is preferably a sintered porous body. The material of the porous body as well as the material of the enclosing layer are selected from a group consisting of tungsten, molybdenum, niobium, chromium, vanadium, titanium, carbon, alloys of these materials, and compounds of these materials. The filler material is preferably a metal selected from a group consisting of silver, gold, copper, aluminum, and alloys of these elements containing not less than a predominant proportion of at least one of these metals. The enveloping layer may be in the form of a sheet material container and lid which are tightly sealed together such as by welding or may be formed of a layer or coating of a portion of the porous body which layer or coating is tightly sealed to a sheet metal portion such as a lid.

Rotatable anode for an X-ray tube composed of a coated, porous body

In order to reduce stresses which occur during radiation production because of the heating-up of the anode, radial bores are formed in the main body member of the anode which extend under the focus path region. Thus, smooth solder surfaces free from recesses can be obtained for receiving auxiliary material such as graphite for increased heat storage and radiation capability. The disclosed rotating anode is particularly suited for x-ray tubes utilized in medical diagnostics.

Rotating anode for x-ray tubes

Tubular electromagnetic components are mounted on the drive shaft of the ary anode of an X-ray tube and external magnet windings are provided both for maintaining the drive shaft in an axial position corresponding to a working position of the anode and for shifting the drive shaft to open a slip contact at one end thereof, thus providing a magnetic switch for the anode supply voltage. In addition, windings are provided through which a controlled current flows to provide a radially stabilized position for the shaft and thus constitute magnetic bearings that are free of friction. When one of the contacts of the magnetic switch is spring-mounted, the coil that does the switching can also be used to adjust the axial position of the anode so as to work with a different cathode.

A soldering connection between metal and ceramics, wherein the parts consisting of metal and ceramics engage each other as a plug and a socket. The invention is particularly characterized in that only parts of metallic and ceramic surfaces which are next to each other are soldered to each other.

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Kleinseebach, Germany

Rudolf Friedel