JP2007042434A - X-ray tube - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an X-ray tube 11 wherein temperature of a power feeding part 26 is reduced by improving heat radiation characteristics of a supporting body 19. <P>SOLUTION: A positive electrode target 16 and a negative electrode filament 18 are provided in an envelope 12. The positive electrode target 16 is supported by an end of the supporting body 19, and the other end of the supporting body 19 is protruded outside of the envelope 12. The power feeding part 26 to the positive electrode target 16 is provided in the other end of the supporting body 19. The envelope 12 and the other end side of the supporting body 19 are housed in the tube container 27, and an insulating material 33 is filled in the tube container 27. The other end side of the supporting body 19 and between the envelope 12 and the power feeding part 26 is connected with the tube container 27 with the connection part 28 in contact with the insulating material 33. The supporting body 19 is held with the connection part 28, the heat stored in the insulating material 33 is radiated, and the heat of the supporting body 19 is transmitted to the insulating material 33 or the tube container 27 easily to be radiated so that the heat radiation characteristics of the supporting body 19 is improved. The temperature of the power feeding part 26 is reduced according to a spatial relationship of the connection part 28 of the supporting body 19 and the power feeding part 26. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an X-ray tube that generates X-rays.

  Conventionally, as shown in FIG. 12, an X-ray tube emits electrons from the cathode filament 2 by applying a high voltage between the cathode filament 2 and the anode target 3 accommodated in the vacuum envelope 1. The electrons are accelerated by the potential difference between the cathode filament 2 and the anode target 3 and collide with the anode target 3. X-rays are generated and emitted from the output window 4 of the vacuum envelope 1. The coolant is circulated through the coolant path 6 inside the support 5 that supports the anode target 3, and the anode target 3 that generates heat due to collision of electrons is cooled. A cooling liquid path 7 for cooling the vacuum envelope 1 is also provided.

Further, the vacuum envelope containing the anode target and the cathode filament is housed in a housing filled with insulating oil, and the end portion of the anode protruding outside the vacuum envelope is electrically insulated heat conducting member. There is an X-ray tube connected to the inner wall surface of the housing via The power feeding part to the anode is between the vacuum envelope and the heat conducting member on the end side of the anode protruding from the vacuum envelope, and a high voltage from the high voltage transformer is applied to the anode through this power feeding part. (For example, refer to Patent Document 1).
JP-A-6-251735 (page 2-3, FIG. 1-2)

  However, in the case of a structure that circulates the cooling liquid inside the support that supports the anode target and cools the heat generated in the anode target, a circulating cooling system for the circulating liquid using a heat exchanger, a circulation pump, a hose, etc. This requires maintenance work and costs. In particular, when pure water is used as the circulating fluid, a filter using an ion exchange resin is required to prevent the electrical conductivity of the pure water from increasing, which requires more maintenance and cost.

  In addition, in the case of a structure in which the end of the anode protruding outside the vacuum envelope is connected to the inner wall surface of the housing via an electrically insulating heat conducting member, the power feeding portion to the anode is connected from the vacuum envelope. The end of the projecting anode is located between the vacuum envelope and the heat conducting member, and the temperature of the power feeding portion is higher than that of the heat conducting member of the anode, which affects the withstand voltage and the like.

  This invention is made | formed in view of such a point, and it aims at providing the X-ray tube which can improve the discharge | release characteristic of the heat | fever of a support body and can reduce the temperature of an electric power feeding part.

  The present invention provides an envelope having an output window that transmits X-rays, an anode target provided in the envelope, and supports the anode target at one end, and the other end of the envelope. A support projecting to the outside, a power feeding part to the anode target connected to the other end of the support, a cathode filament provided in the envelope and emitting electrons to be irradiated to the anode target; A tube container accommodating at least a part of the envelope and the other end of the support projecting from the envelope; an insulating material filled in the tube container; and the support projecting from the envelope A connecting portion disposed on the other end side of the body and connected between the envelope and the power feeding portion to the tube container and arranged so that a surface thereof is in contact with the insulating material. .

  According to the present invention, the support body is held by the other end side of the support body protruding from the envelope and connected between the envelope and the power feeding section to the tube container, and accumulated in the insulating material. Heat can be dissipated through the support that comes into contact with it, and heat from the support can be transferred to the insulating material and tube container to easily dissipate it from the tube container, improving the heat release characteristics of the support. Furthermore, the temperature of the power feeding part can be reduced by the positional relationship between the connection part and the power feeding part with respect to the support.

  Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

  1 to 5 show a first embodiment, FIG. 1 is a sectional view of a basic structure of an X-ray tube, and FIGS. 2 to 5 are partial views showing other shapes of connecting portions of the X-ray tube, respectively. It is sectional drawing.

  As shown in FIG. 1, 11 is a fixed anode type X-ray tube, and this X-ray tube 11 is provided with an envelope 12 that holds the inside in a vacuum. The envelope 12 is composed of a vacuum envelope 13 on one end side in the axial direction along the tube axis of the X-ray tube 11 and insulation on the other end side which is a part constituting a high voltage insulation portion of the envelope 12. It is configured in combination with the envelope 14.

  The vacuum envelope 13 has a cylindrical shape whose outer diameter is gradually narrowed, the tip surface is formed flat, and an output window 15 that transmits X-rays is provided in the flat portion. For example, beryllium (Be) is used for the output window 15 as a material with little attenuation of X-rays, and the thickness is formed to be several tens to several hundreds μm.

  The insulating envelope 14 is formed in a cylindrical shape with an insulating material containing electrically insulating ceramics.

  An anode target 16 is disposed inside the vacuum envelope 13 so as to face the output window 15, a focusing electrode 17 is disposed outside the anode target 16, and a cathode filament 18 is disposed outside the focusing electrode 17. Is arranged. The cathode filament 18 is fixed to the outer peripheral portion of the focusing electrode 17.

  A support 19 is disposed at the center of the envelope 12, and one end of the support 19 is disposed inside the focusing electrode 17 and supports the anode target 16 at the tip. The peripheral surface of the other end side of the support body 19 is connected and held in a sealed state to the other end side of the insulating envelope 14 by a connecting member 20, and the other end side of the support body 19 is connected to the outside of the insulating envelope 14. A protruding portion 21 that protrudes is formed. A fitting portion 22 having a small diameter is formed on the other end side of the support body 19 protruding from the insulating envelope 14.

  An exhaust pipe 24 for exhausting the inside of the envelope 12 through an exhaust path 23 formed inside the support body 19 is provided on the end surface of the projecting portion 21 which is the other end of the support body 19, and an anode A power feeding unit 26 to which a high voltage cable 25 for applying a high voltage to the target 16 is connected is provided.

  In addition, the insulating envelope 14 which is a portion constituting the high voltage insulating portion of the envelope 12 and the protruding portion 21 of the support body 19 protruding from the insulating envelope 14 are formed of an insulating material. Is accommodated in a tube container 27.

  In addition, the support body 19 and the tube container 27 are connected in the radial direction between the insulation envelope 14 and the power feeding section 26 in the fitting portion 22 of the support body 19 protruding from the insulation envelope 14. A connecting portion 28 is disposed so that the surface thereof is in contact with the insulating material 33. The connecting portion 28 is made of a ceramic having a high thermal conductivity of 20 W / m · K or higher and a high voltage insulating property of 10 kV / mm or higher, and is formed in an annular shape, and is fitted to the fitting portion 22 of the support 19 on the inside. Thus, a fitting hole 29 to be joined is formed, and a joining portion 30 to be joined to the inner peripheral surface of the tube container 27 is formed on the outer peripheral surface. The surface portion 31 facing the inside of the envelope 12 of the connection portion 28 is subjected to blasting as means for increasing the surface area of the surface portion 31. The connecting portion 28 fitted to the fitting portion 22 of the support 19 is held by the support 19 with a holding member 32. If the high heat conductivity is 20 W / m · K or less, sufficient heat conduction cannot be obtained, and if the high voltage insulation is 10 kV / mm or less, it cannot be used. As the ceramic material of the connection portion 28, for example, aluminum nitride is used, so that a high thermal conductivity of 90 to 200 W / m · K can be obtained.

  The tube container 27 is filled with an insulating material 33 which is a potting material such as silicone resin.

  A cooling means 34 for cooling the tube container 27 is disposed on the outer surface of the tube container 27, including at least an outer peripheral surface that is a portion of the tube container 27 to which the connection portion 28 is connected. As the cooling means 34, for example, air cooling or liquid cooling can be selected according to the input of the X-ray tube 11, but air cooling that is easy to maintain is preferable.

  During the operation of the X-ray tube 11, electrons are emitted from the cathode filament 18 by applying a high voltage between the cathode filament 18 accommodated in the envelope 12 and the anode target 16. Accelerated by the potential difference between the cathode filament 18 and the anode target 16 and colliding with the anode target 16, X-rays are generated and emitted from the output window 15 of the vacuum envelope 13.

  Heat is generated by the collision of electrons with the anode target 16, the heat of the anode target 16 is transmitted to the support 19, and the insulating material 33 and the like through the connection portion 28 connected to the other end of the support 19. Dissipated and transferred to the tube container 27 and the like. The heat transmitted from the connecting portion 28 or the insulating material 33 to the tube container 27 is radiated by the cooling means 34 that cools the outer surface of the tube container 27.

  For example, when the heat load of the X-ray tube 11 is 200 W and the connection portion 28 is present, the temperature of the anode target 16 using palladium (Pd) is 700 ° C. or less. The thermal analysis results revealed that the temperature of the anode target 16 using Pd) was 1000 ° C. or higher. When the temperature of the anode target 16 is 700 ° C. or higher, there may be a case where the X-ray intensity is lowered or a withstand voltage problem occurs.

  In this manner, the support body 19 is held by the connection portion 28 that connects the tube container 27 between the insulation envelope 14 and the power feeding portion 26 on the other end side of the support body 19 protruding from the insulation envelope 14. At the same time, the heat accumulated in the insulating material 33 is radiated through the support 19 in contact therewith, and the heat of the support 19 is transmitted to the insulating material 33 and the tube container 27 to be radiated from the tube container 27. It is easy to maintain, and maintenance is not required as in the case of using a cooling liquid, the heat release characteristics of the support 19 can be improved, and further, the power supply unit 26 depends on the positional relationship between the connection unit 28 and the power supply unit 26 with respect to the support 19. Temperature can be reduced.

  Since the surface portion 31 in contact with the insulating material 33 of the connecting portion 28 is blasted, the surface area in contact with the insulating material 33 is larger than that of the flat surface, and heat transfer from the connecting portion 28 to the insulating material 33 can be improved. At the same time, the creepage distance can be secured.

  By using ceramics having a thermal conductivity of 20 W / m · K or higher, a dielectric strength of 10 kV / mm or higher, for example, aluminum nitride, as the material of the connection portion 28, both high thermal conductivity and high insulation can be achieved.

  The means for increasing the surface area of the surface portion 31 in contact with the insulating material 33 of the connecting portion 28 is not limited to blasting. For example, the surface portion 31 of the connecting portion 28 is corrugated as shown in FIG. 2, the surface portion 31 of the connecting portion 28 is formed in an uneven shape as shown in FIG. 3, or the connecting portion 28 is shown in FIG. The insulating material 33 of the connecting portion 28 can also be obtained by increasing the width of the peripheral edge in contact with the tube container 27 or by increasing the width of the connecting portion 28 stepwise as it goes in the outer diameter direction as shown in FIG. The surface area of the surface portion 31 in contact with can be increased.

  Next, FIGS. 6 to 11 show a second embodiment, FIG. 6 is a cross-sectional view of the basic structure of the X-ray tube, and FIGS. 7 to 11 show other shapes of connecting portions of the X-ray tube, respectively. FIG.

  A fitting portion 22 of the support body 19 protruding from the insulating envelope 14, and a connection portion for connecting the support body 19 and the tube container 27 in the axial direction between the insulation envelope 14 and the power feeding portion 26 28 is arranged. The connection portion 28 is formed in an annular shape (cylindrical shape), and a fitting hole 29 is formed on the inner side to be fitted and joined to the fitting portion 22 of the support body 19. The outer end surface is formed on the end surface of the tube container 27. A joining portion 30 to be joined is formed. The surface portion 31 facing the inside of the envelope 12 of the connecting portion 28 is subjected to blasting as means for increasing the surface area.

  A cooling means 34 for cooling the tube container 27 is disposed on the outer surface of the tube container 27, including at least an end surface that is a part of the tube container 27 to which the connection portion 28 is connected.

  Then, during operation of the X-ray tube 11, heat generated by the collision of electrons with the anode target 16 is transmitted to the support 19 and insulated through the connection portion 28 connected to the other end of the support 19. It is dissipated and transferred to the material 33 and the tube container 27. The heat transmitted from the connecting portion 28 or the insulating material 33 to the tube container 27 is radiated by the cooling means 34 that cools the outer surface of the tube container 27.

  In this manner, the support body 19 is held by the connection portion 28 that connects the tube container 27 between the insulation envelope 14 and the power feeding portion 26 on the other end side of the support body 19 protruding from the insulation envelope 14. At the same time, the heat accumulated in the insulating material 33 is radiated through the support 19 in contact therewith, and the heat of the support 19 is transmitted to the insulating material 33 and the tube container 27 to be radiated from the tube container 27. It is easy to maintain, and maintenance is not required as in the case of using a cooling liquid, the heat release characteristics of the support 19 can be improved, and further, the power supply unit 26 depends on the positional relationship between the connection unit 28 and the power supply unit 26 with respect to the support 19. Temperature can be reduced.

  The means for increasing the surface area of the surface portion 31 in contact with the insulating material 33 of the connecting portion 28 is not limited to blasting. For example, as shown in FIG. 7, the inner diameter of the portion of the fitting hole 29 of the connecting portion 28 that is not fitted to the support 19 is widened, or the surface portion 31 of the connecting portion 28 is uneven as shown in FIG. 9, the surface portion 31 of the connecting portion 28 is corrugated as shown in FIG. 9, and the outer diameter of the connecting portion 28 is increased stepwise as it goes to the other end in the axial direction as shown in FIG. Alternatively, as shown in FIG. 11, the surface area of the surface portion 31 in contact with the insulating material 33 in the connection portion 28 can also be increased by increasing the width of the edge portion in contact with the tube container 27 of the connection portion 28.

It is sectional drawing of the basic structure of the X-ray tube which shows the 1st Embodiment of this invention. It is a partial cross section figure which shows the other shape of the connection part of an X-ray tube same as the above. It is a partial cross section figure which shows the other shape of the connection part of an X-ray tube same as the above. It is a partial cross section figure which shows the other shape of the connection part of an X-ray tube same as the above. It is a partial cross section figure which shows the other shape of the connection part of an X-ray tube same as the above. It is sectional drawing of the X-ray tube which shows the 2nd Embodiment of this invention. It is a partial cross section figure which shows the other shape of the connection part of an X-ray tube same as the above. It is a partial cross section figure which shows the other shape of the connection part of an X-ray tube same as the above. It is a partial cross section figure which shows the other shape of the connection part of an X-ray tube same as the above. It is a partial cross section figure which shows the other shape of the connection part of an X-ray tube same as the above. It is a partial cross section figure which shows the other shape of the connection part of an X-ray tube same as the above. It is a partial sectional view showing a conventional X-ray tube.

Explanation of symbols

11 X-ray tube
12 Envelope
15 Output window
16 Anode target
18 Cathode filament
19 Support
26 Feeder
27 tube container
28 Connection
33 Insulation material
34 Cooling means

Claims (6)

An envelope having an output window that transmits X-rays;
An anode target provided in the envelope;
The anode target is supported at one end, and the other end protrudes outside the envelope; and
A power feeding part to the anode target connected to the other end of the support;
A cathode filament that is provided in the envelope and emits electrons to irradiate the anode target;
A tube container that houses at least a part of the envelope and the other end of the support projecting from the envelope;
An insulating material filled in the tube container;
A connecting portion arranged on the other end side of the support projecting from the envelope and between the envelope and the power feeding portion so as to be connected to the tube container and its surface in contact with the insulating material. An X-ray tube comprising: The X-ray tube according to claim 1, wherein the connecting portion connects the support and the tube container in either the radial direction or the axial direction. 3. The X-ray tube according to claim 1, wherein means for increasing a surface area of the surface is provided on a surface of the connecting portion in contact with the insulating material. The X-ray tube according to any one of claims 1 to 3, wherein the connecting portion is made of a ceramic having a thermal conductivity of 20 W / m · K or more. The X-ray tube according to any one of claims 1 to 4, wherein the connecting portion is formed of a ceramic having a dielectric strength of 10 kV / mm or more. The X-ray tube according to any one of claims 1 to 5, further comprising cooling means for cooling an outer surface of the tube container.

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