JP2014229492A - Electron gun and radiation generating device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an electron gun whose performance degradation is suppressed.SOLUTION: An electron gun capable of emitting thermal electrons includes: a first portion having an electron emission surface orthogonal to a predetermined axis; a cathode including a second portion whose contour in a surface orthogonal to the predetermined axis is smaller than that of the first portion; and a heater which supports the second portion. The heater has a recess in which at least a part of the second portion is arranged.

Description

  The present invention relates to an electron gun and a radiation generator.

  A radiation generating apparatus such as an X-ray source includes an electron gun and a target irradiated with an electron beam from the electron gun. As disclosed in, for example, the following patent document, the electron gun includes a cathode capable of emitting electrons (thermoelectrons), a heater that supports and heats the cathode, and a support electrode that supports the heater.

Japanese Patent No. 5047062 Japanese Patent Publication No.59-011172 Japanese Utility Model Publication No. 60-013163

  For example, if the position of at least one of the cathode and the heater changes due to the action of an external force on the electron gun, the traveling direction of the electron beam may change or the cathode may not be sufficiently heated. As a result, the performance of the electron gun and the radiation generator may be reduced.

  It is an object of the present invention to provide an electron gun and a radiation generation apparatus in which a decrease in performance is suppressed.

  An electron gun according to the present invention is capable of emitting thermoelectrons, and has a first portion having an electron emission surface orthogonal to a predetermined axis, and an outer shape in a plane orthogonal to the predetermined axis smaller than that of the first portion. A cathode including two portions and a heater supporting the second portion, the heater having a recess in which at least a part of the second portion is disposed.

  According to the present invention, the change in the position of the cathode with respect to the heater is suppressed by disposing at least a part of the second portion of the cathode in the recess of the heater. When the inner surface of the recess comes into contact with the surface of the cathode (second portion), for example, a change in the position of the cathode with respect to the direction intersecting the inner surface is suppressed. Further, the contact area between the inner surface of the recess and the surface of the cathode increases the contact area between the cathode and the heater, and the frictional force between the cathode and the heater increases. Thereby, the change of the position of the cathode with respect to a heater is suppressed. Further, when the contact area between the cathode and the heater is increased, the cathode is efficiently heated by the heater. Accordingly, a decrease in performance is suppressed. According to the present invention, the second portion is supported by the heater, and the electron emission surface is provided in the first portion larger than the second portion. Thereby, many thermoelectrons are stably emitted from the electron emission surface of the first portion.

  In the electron gun according to the present invention, the heater is disposed on each of one side and the other side of the predetermined axis with respect to a direction parallel to the first axis in a plane orthogonal to the predetermined axis, and the second portion is Two heaters sandwiched and supported, and an inner surface of the recess is at least a surface of the second portion on one side of the predetermined axis with respect to a direction parallel to a second axis perpendicular to the first axis in the surface You may contact a part and at least a part of the surface of the second part on the other side. By arranging the heaters on one side and the other side of the predetermined axis (cathode) with respect to the direction parallel to the first axis, a change in the position of the cathode with respect to the direction parallel to the first axis is suppressed. The position of the cathode in the direction parallel to the second axis by supporting at least a part of the surface of the second part on one side and the other side of the predetermined axis (cathode) with respect to the direction parallel to the second axis. The change of is suppressed. In addition, since at least four portions of the surface of the second portion are supported by the two heaters, not only the displacement of the cathode in the translation direction but also the displacement of the cathode in the rotation direction is suppressed.

  In the electron gun according to the present invention, the second portion is disposed substantially around the predetermined axis in parallel with the predetermined axis, and the first surface with which at least a part of the inner surface of the recess contacts, and the predetermined portion A second surface intersecting an axis parallel to the axis, and the heater may be disposed outside the recess and have an outer surface that contacts at least a part of the second surface. By supporting the first surface with the inner surface of the recess, for example, the displacement of the cathode in a plane orthogonal to the predetermined axis is suppressed. Further, the second surface intersecting the axis parallel to the predetermined axis is supported by the outer surface of the heater, so that, for example, the displacement of the cathode in the direction parallel to the predetermined axis is suppressed.

  In the electron gun according to the present invention, the second part is rod-shaped, one end of the second part is connected to the first part, the cathode is connected to the other end of the second part, A third portion having an outer shape in a plane perpendicular to the predetermined axis may be included that is larger than the second portion. The first portion is disposed on one end portion side of the second portion, and the third portion is disposed on the other end portion side of the second portion, so that the mass (weight) balance between the one end portion side and the other end portion side is increased. Will improve. Thereby, even if an external force acts, for example, the displacement of the cathode in the rotation direction is suppressed.

  The electron gun according to the present invention includes a support electrode that supports the heater, and a support surface of the support electrode faces a first region that the heater contacts and a direction different from the first region, and the heater A second region in contact with the second region. Thereby, the change of the position of the heater with respect to a support electrode is suppressed. For example, when the first region of the support electrode is in contact with the heater, a change in the position of the heater in the direction intersecting the first region is suppressed. When the second region of the support electrode is in contact with the heater, a change in the position of the heater in the direction intersecting the second region is suppressed. Further, not only the displacement of the heater in the translation direction, but also the displacement of the cathode in the rotation direction is suppressed. In addition, since the change in the position of the heater is suppressed, the change in the position of the cathode supported by the heater is also suppressed.

  An electron gun according to the present invention includes a cathode from which thermal electrons are emitted, a heater that supports the cathode, and a support electrode that supports the heater, and the support surface of the support electrode is in contact with the heater. A first region and a second region facing a direction different from the first region and contacting the heater.

  According to the present invention, the support surface of the support electrode in contact with the heater includes the first region and the second region facing in a direction different from the first region, and each of the first region and the second region is a heater. Therefore, the change in the position of the heater with respect to the support electrode is suppressed. For example, when the first region of the support electrode is in contact with the heater, a change in the position of the heater in the direction intersecting the first region is suppressed. When the second region of the support electrode is in contact with the heater, a change in the position of the heater in the direction intersecting the second region is suppressed. Further, not only the displacement of the heater in the translation direction, but also the displacement of the cathode in the rotation direction is suppressed. In addition, since the change in the position of the heater is suppressed, the change in the position of the cathode supported by the heater is also suppressed. Accordingly, a decrease in performance is suppressed.

  In the electron gun according to the present invention, the support surface may include a concave surface. Since the heater is supported by the support surface including the concave surface, the displacement of the heater is suppressed, and the displacement of the cathode supported by the heater is also suppressed.

  The electron gun according to the present invention may include a support member that supports a portion of the cathode that is different from the portion supported by the heater. Since the cathode is supported not only by the heater but also by the support member, the position of the cathode is fixed well.

  In the electron gun according to the present invention, the second portion may have a hole, and at least a part of the support member may be disposed in the hole. Thereby, the change of the relative position of a cathode and a supporting member is suppressed, and the position of a cathode is fixed favorably.

  A radiation generating apparatus according to the present invention includes any one of the above electron guns and a target irradiated with an electron beam from the electron gun.

  According to the present invention, since the decrease in the performance of the electron gun is suppressed, the decrease in the performance of the radiation generating apparatus including the electron gun is also suppressed.

  According to the electron gun and the radiation generation apparatus according to the present invention, performance degradation is suppressed.

FIG. 1 is a diagram illustrating an example of an electron gun according to the first embodiment. FIG. 2 is a perspective view showing an example of the cathode according to the first embodiment. FIG. 3 is a perspective view showing an example of a heater according to the first embodiment. FIG. 4 is a front view illustrating an example of a cathode and a heater according to the first embodiment. FIG. 5 is a view taken along line AA in FIG. FIG. 6 is a perspective view showing an example of a heater according to the second embodiment. FIG. 7 is a cross-sectional view illustrating an example of a cathode and a heater according to the second embodiment. FIG. 8 is a cross-sectional view illustrating an example of a cathode and a heater according to the second embodiment. FIG. 9 is a cross-sectional view illustrating an example of a cathode and a heater according to the second embodiment. FIG. 10 is a perspective view illustrating an example of a heater according to the third embodiment. FIG. 11 is a cross-sectional view illustrating an example of a cathode and a heater according to the third embodiment. FIG. 12 is a perspective view illustrating an example of a cathode and a heater according to the fourth embodiment. FIG. 13 is a perspective view illustrating an example of a heater according to the fourth embodiment. FIG. 14 is a perspective view illustrating an example of a cathode and a heater according to the fourth embodiment. FIG. 15 is a perspective view illustrating an example of a heater according to the fourth embodiment. FIG. 16 is a perspective view illustrating an example of a cathode and a heater according to the fifth embodiment. FIG. 17 is a perspective view illustrating an example of a heater according to the fifth embodiment. FIG. 18 is a perspective view illustrating an example of a heater according to the fifth embodiment. FIG. 19 is a cross-sectional view illustrating an example of a cathode and a heater according to the sixth embodiment. FIG. 20 is a diagram illustrating an example of a cathode and a heater according to the seventh embodiment. FIG. 21 is a diagram illustrating an example of a cathode, a heater, and a support electrode according to the eighth embodiment. FIG. 22 is a BB line arrow view of FIG. FIG. 23 is a perspective view showing an example of a heater and a support electrode according to the eighth embodiment. FIG. 24 is a perspective view illustrating an example of a heater and a support electrode according to the eighth embodiment. FIG. 25 is a perspective view illustrating an example of a heater and a support electrode according to the eighth embodiment. FIG. 26 is a perspective view illustrating an example of a heater and a support electrode according to the eighth embodiment. FIG. 27 is a perspective view illustrating an example of a heater and a support electrode according to the eighth embodiment. FIG. 28 is a perspective view showing an example of a support electrode according to the eighth embodiment. FIG. 29 is a perspective view showing an example of a support electrode according to the eighth embodiment. FIG. 30 is a perspective view showing an example of a support electrode according to the eighth embodiment. FIG. 31 is a cross-sectional view illustrating an example of a cathode, a heater, and a support electrode according to the ninth embodiment. FIG. 32 is a diagram illustrating an example of a radiation generation apparatus according to the tenth embodiment.

  Hereinafter, embodiments according to the present invention will be described with reference to the drawings, but the present invention is not limited thereto. The requirements of the embodiments described below can be combined as appropriate. Some components may not be used.

  In the following description, an XYZ orthogonal coordinate system is set, and the positional relationship of each part will be described with reference to this XYZ orthogonal coordinate system. One direction in the predetermined plane is defined as the X-axis direction, the direction orthogonal to the X-axis direction in the predetermined plane is defined as the Y-axis direction, and the direction orthogonal to each of the X-axis direction and the Y-axis direction is defined as the Z-axis direction. Further, the rotation (inclination) directions around the X axis, Y axis, and Z axis are the θX, θY, and θZ directions, respectively. The X axis is orthogonal to the YZ plane. The Y axis is orthogonal to the XZ plane. The Z axis is orthogonal to the XY plane. The XY plane includes an X axis and a Y axis. The YZ plane includes a Y axis and a Z axis. The XZ plane includes an X axis and a Z axis.

<First Embodiment>
A first embodiment will be described. FIG. 1 is a diagram illustrating an example of an electron gun 1 according to the present embodiment. The electron gun 1 includes a cathode 2 that can emit electrons (thermoelectrons), a Wehnelt electrode 3, and an anode 4. The cathode 2, the Wehnelt electrode 3 and the anode 4 are arranged along a common axis J. In the present embodiment, the axis J is parallel to the Z axis. The axis J includes the central axis of the electron gun 1. The Wehnelt electrode 3 and the anode 4 are arranged on the + Z side with respect to the cathode 2.

  The Wehnelt electrode 3 has an opening (passage) 3K through which electrons from the cathode 2 can pass. The Wehnelt electrode 3 is disposed so that the center of the opening 3K coincides with the axis J. The anode 4 has an opening (passage) 4K through which electrons from the cathode 2 can pass. The anode 4 is disposed so that the center of the opening 4K and the axis J coincide.

The cathode 2 is an electron source capable of generating electrons. The cathode 2 can emit electrons (thermoelectrons) when heated. The cathode 2 is formed of a rare earth hexaboride having thermionic emission characteristics. The cathode 2 may include lanthanum hexaboride (LaB ₆ ) or cerium hexaboride (CeB ₆ ).

  The Wehnelt electrode 3 focuses the electrons emitted from the cathode 2. The anode 4 accelerates the electrons emitted from the cathode 2. Electrons emitted from the cathode 2 are accelerated by an electric field between the cathode 2 and the anode 4. Electrons emitted from the cathode 2 are focused and accelerated, whereby an electron beam is emitted from the electron gun 1.

  At least a part of the electrons (electron beam) travels along the axis J. In the present embodiment, electrons (electron beams) travel in the + Z direction. In the present embodiment, the + Z direction (+ Z side) is the traveling direction of the electron beam. The −Z direction (−Z side) is the reverse direction of the traveling direction of the electron beam.

  The electron gun 1 includes a heater 5 that supports the cathode 2, a support electrode 6 that supports the heater 5, and an insulating member 7 that supports the support electrode 6.

  The heater 5 supports the cathode 2. At least a part of the heater 5 is in contact with the cathode 2. The heater 5 can heat the cathode 2. The heater 5 is a member that can be energized. The heater 5 is a member containing carbon (graphite). When a current is passed through the heater 5, the temperature of the heater 5 rises. As a result, the cathode 2 is heated by the heater 5.

  The cathode 2 is supported by being sandwiched between two heaters 5. The heater 5 is disposed on one side (+ X side) and the other side (−X side) with respect to the axis J. In the following description, one of the two heaters 5 sandwiching the cathode 2 is appropriately referred to as a first heater 51, and the other heater 5 is appropriately referred to as a second heater 52. In the present embodiment, the first heater 51, the cathode 2, and the second heater 52 are arranged in the X-axis direction. At least a part of the first heater 51 is disposed on the + X side of the cathode 2. At least a part of the second heater 52 is disposed on the −X side of the cathode 2. The first heater 51 and the second heater 52 are supported with the cathode 2 interposed therebetween.

  The support electrode 6 supports the heater 5. At least a part of the support electrode 6 is in contact with the heater 5. Two support electrodes 6 are provided so as to support each of the first heater 51 and the second heater 52. In the following description, the support electrode 6 that supports the first heater 51 is appropriately referred to as a first support electrode 61, and the support electrode 6 that supports the second heater 52 is appropriately referred to as a second support electrode 62. A first heater 51 is disposed between the first support electrode 61 and the cathode 2. A second heater 52 is disposed between the second support electrode 62 and the cathode 2. The first heater 51, the cathode 2, and the second heater 52 are sandwiched and supported by the first support electrode 61 and the second support electrode 62. When a current is passed through the support electrode 6, the heater 5 with high electrical resistance generates heat (Joule heat generation). As the heater 5 generates heat, the cathode 2 is heated.

  FIG. 2 is a perspective view showing an example of the cathode 2 according to the present embodiment. FIG. 3 is a perspective view showing an example of the heater 5 according to the present embodiment. FIG. 4 is a front view showing an example of a state in which the second portion 12 is supported by the two heaters 5 (the first heater 51 and the second heater 52). FIG. 5 is a view taken along line AA in FIG.

  The cathode 2 includes a first portion 11 having an electron emission surface 8 from which electrons (thermoelectrons) are emitted, and a second portion 12 supported by the heater 5. In the present embodiment, the electron emission surface 8 is a flat surface (flat). The cathode 2 is supported by the heater 5 so that the electron emission surface 8 and the XY plane are parallel to each other. The cathode 2 is supported by the heater 5 so that the electron emission surface 8 and the axis J (Z axis) are orthogonal to each other.

  In the XY plane orthogonal to the axis J, the outer shape of the second portion 12 is smaller than the outer shape of the first portion 11. The outer shape of the first portion 11 in the XY plane is a circle. The electron emission surface 8 is circular. The first portion 11 has a plate shape (disk shape). The first portion 11 has a surface 9 facing the direction opposite to the electron emission surface 8. The electron emission surface 8 faces the + Z direction. The plane 9 faces the −Z direction. The cathode 2 is supported by the heater 5 so that the center of the electron emission surface 8 and the axis J coincide.

  The second portion 12 has a rod shape. In the present embodiment, the second portion 12 has a cylindrical shape. The outer shape of the second portion 12 in the XY plane is a circle. The cathode 2 is supported by the heater 5 so that the axis parallel to the longitudinal direction of the rod-shaped second portion 12 and the axis J coincide. In the XY plane, the outer shape of the first portion 11 is larger than the outer shape of the second portion 12. The second portion 12 is disposed in a space opposite to the space where the electron emission surface 8 faces (the space where the surface 9 faces) with respect to the first portion 11. The second portion 12 is disposed on the −Z side with respect to the first portion 11. The second portion 12 is disposed so as to be connected to the surface 9 of the first portion 11.

  The surface of the second portion 12 includes a surface 145 disposed around the axis J and a surface 21 facing the direction opposite to the electron emission surface 8. In the following description, the surface 145 is appropriately referred to as a side surface 145, and the surface 21 is appropriately referred to as a lower surface 21. The side surface 145 is substantially parallel to the Z axis (axis J). The phrase “substantially parallel to the Z axis (axis J)” includes a state of being completely parallel to the Z axis (axis J). Further, the phrase “substantially parallel to the Z axis (axis J)” includes a state in which the axis is inclined at, for example, 1 degree to 10 degrees with respect to the Z axis (axis J). The lower surface 21 faces the −Z direction. In the present embodiment, the lower surface 21 is substantially parallel to the XY plane.

  The heater 5 has a recess 30 in which at least a part of the second portion 12 is disposed. The recess 30 has an inner surface 35. At least a part of the inner surface 35 can contact the side surface 145 of the second portion 12. The inner surface 35 of the heater 5 that can contact at least a part of the cathode 2 functions as a support surface that supports the cathode 2.

  The inner surface 35 includes a first inner surface 351 and a second inner surface 352 that faces a direction different from the first inner surface 351. The first inner surface 351 and the second inner surface 352 are arranged in the Y-axis direction. The first inner surface 351 and the second inner surface 352 are each flat (flat). The outer shape of the first inner surface 351 and the outer shape of the second inner surface 352 are substantially equal. In the present embodiment, the outer shape of the first inner surface 351 and the outer shape of the second inner surface 352 are each rectangular. Each of the first inner surface 351 and the second inner surface 352 is disposed substantially parallel to the Z axis (axis J). Each of the first inner surface 351 and the second inner surface 352 is inclined with respect to the XZ plane (YZ plane). The angle formed by the first inner surface 351 and the second inner surface 352 is smaller than 180 degrees. In the present embodiment, the recess 30 includes a so-called triangular groove. Each of the first inner surface 351 and the second inner surface 352 can face the side surface 145.

  The heater 5 has an outer surface 31 disposed outside the recess 30 (inner surface 35). The outer surface 31 is arrange | positioned with respect to the recessed part 30 (inner surface 35) on each of + Y side and -Y side. The outer surface 31 is substantially parallel to the YZ plane.

  As shown in FIGS. 4 and 5, at least a part of the second portion 12 is disposed in the recess 30. The heater 5 supports the second portion 12. The first heater 51 and the second heater 52 are supported with the second portion 12 interposed therebetween. The first heater 51 is disposed on the + X side of the axis J. The second heater 52 is disposed on the −X side of the axis J. The first heater 51 and the second heater 52 are disposed so that the recess 30 of the first heater 51 and the recess 30 of the second heater 52 face each other. The second portion 12 is disposed between the recess 30 of the first heater 51 and the recess 30 of the second heater 52. In a state where the second portion 12 is disposed between the concave portion 30 of the first heater 51 and the concave portion 30 of the second heater 52, there is a gap between the outer surface 31 of the first heater 51 and the outer surface 31 of the second heater 52. Opposite through.

  As shown in FIG. 5, a first gap (first space) 41 in which the second portion 12 is disposed and a second gap in which the second portion 12 is not disposed between the first heater 51 and the second heater 52. (Second space) 42 is formed. The first gap 41 includes a space between the inner surface 35 of the first heater 51 and the inner surface 35 of the second heater 52. The second gap 42 includes a space between the outer surface 31 of the first heater 51 and the outer surface 31 of the second heater 52. The second gap 42 is formed on both sides (+ Y side and −Y side) of the first gap 41 in the Y-axis direction. With respect to the X-axis direction, the dimension W2 of the second gap 42 is smaller than the dimension W1 of the first gap 41.

  The first inner surface 351 and the second inner surface 352 of the first heater 51 and the second heater 52 can contact the side surface 145 of the second portion 12. The first inner surface 351 and the second inner surface 352 of the first heater 51 can be in contact with the side surface 145 at the same time. The first inner surface 351 and the second inner surface 352 of the second heater 52 can be in contact with the side surface 145 at the same time.

  In the present embodiment, the inner surface 35 of the recess 30 includes at least a part of the side surface 145 of the second part 12 on one side (+ Y side) of the axis J and the second part on the other side (−Y side) in the Y-axis direction. Each of the twelve side surfaces 145 contacts at least a portion. In the present embodiment, the first inner surface 351 of the first heater 51 is in contact with the portion 401 of the side surface 145 on the −Y side and the + X side with respect to the axis J. The second inner surface 352 of the first heater 51 is in contact with the portion 402 of the side surface 145 on the + Y side and the + X side with respect to the axis J. The first inner surface 351 of the second heater 52 is in contact with the portion 403 of the side surface 145 on the + Y side and the −X side with respect to the axis J. The second inner surface 352 of the second heater 52 is in contact with the portion 404 of the side surface 145 on the −Y side and the −X side with respect to the axis J. In the present embodiment, the first inner surfaces 351 of the first heater 51 and the second heater 52 are in line contact with the side surface 145. The second inner surfaces 352 of the first heater 51 and the second heater 52 are in line contact with the side surface 145. The second portion 12 does not come into contact with the heater 5 in a part other than the part 401, the part 402, the part 403, and the part 404.

  As shown in FIG. 4, the heater 5 (the first heater 51 and the second heater 52) is in contact with the second portion 12 and is not in contact with the first portion 11. In a state where the second portion 12 is supported by the heater 5, the heater 5 is separated from the surface 9 of the first portion 11.

  Next, an example of the operation of the electron gun 1 including the cathode 2 according to this embodiment will be described. When a current is passed through the support electrode 6, the heater 5 generates heat. As the heater 5 generates heat, the cathode 2 is heated. When the cathode 2 is heated, electrons (thermoelectrons) are emitted from the electron emission surface 8 of the cathode 2. The electrons emitted from the cathode 2 are focused and accelerated by the Wehnelt electrode 3 and the anode 4, and are irradiated onto the object as an electron beam.

  The electron emission surface 8 is provided in the first portion 11 that is larger than the second portion 12. Since the area of the electron emission surface 8 is large, many electrons can be emitted from the electron emission surface 8. The heater 5 is not in contact with the first portion 11 and is disposed away from the first portion 11. The heater 5 supports the second portion 12 so that the emission of electrons from the electron emission surface 8 is not inhibited. Thereby, the emission of electrons from the electron emission surface 8 is stably performed.

  By disposing at least a part of the second portion 12 in the recess 30 of the heater 5, the position of the cathode 2 is fixed. Even when an external force due to, for example, impact or vibration is applied to the electron gun 1, a change in the position of the cathode 2 with respect to the heater 5 is suppressed. Further, the contact area between the inner surface 35 of the recess 30 and the side surface 145 of the second portion 12 increases the contact area between the cathode 2 and the heater 5. As a result, the frictional force between the cathode 2 and the heater 5 is increased. growing. In the present embodiment, the cathode 2 and the heater 5 (the first heater 51 and the second heater 52) are in contact with each other at the four parts 401, 402, 403, and 404. Therefore, a change in the position of the cathode 2 with respect to the heater 5 is suppressed.

  When the contact area between the cathode 2 and the heater 5 is increased, the cathode 2 is efficiently heated by the heater 5. Further, since the contact area between the cathode 2 and the heater 5 is large, even if the cathode 2 is consumed (evaporated) by heating or the like, for example, the cathode 2 and the heater 5 can be kept in contact for a long time.

  In the present embodiment, the inner surface 35 of the recess 30 includes a first inner surface 351 and a second inner surface 352. When the first inner surface 351 and the second inner surface 352 are in contact with the second portion 12, changes in the position of the cathode 2 in the X axis, Y axis, Z axis, θX, θY, and θZ directions are suppressed. As described above, in this embodiment, the change in the position of the cathode 2 with respect to the three translational directions of the X axis, the Y axis, and the Z axis is suppressed, and the cathode with respect to the three rotational directions of θX, θY, and θZ. The change in the position of 2 is suppressed.

  As described with reference to FIG. 5 and the like, in the present embodiment, the inner surface 35 and the side surface 145 are in contact (line contact) at the four portions 401, 402, 403, and 404 around the axis J. ) Thereby, the change of the position of the cathode 2 is sufficiently suppressed in the six directions of the X axis, the Y axis, the Z axis, θX, θY, and θZ.

  Further, according to the present embodiment, the second portion 12 is disposed in the first gap 41 between the first heater 51 and the second heater 52, and both sides (+ Y side and −Y side) of the first gap 41 in the Y axis direction. A second gap 42 smaller than the first gap 41 is formed on the Y side. As a result, the second portion 12 disposed in the first gap 41 is prevented from moving outside the first gap 41. Therefore, it is possible to suppress the position of the cathode 2 from changing or the cathode 2 from dropping between the first heater 51 and the second heater 52.

  As described above, according to this embodiment, the change in the position of the cathode 2 is suppressed. Further, the cathode 2 is prevented from falling off between the first heater 51 and the second heater 52. In the present embodiment, the cathode 2 includes a second portion 12 and a first portion 11 that is disposed on one end side of the second portion 12 and is larger than the second portion 12, and the second portion 12 is the heater 5. Supported by. Therefore, if the cathode 2 is not sufficiently held, the possibility that the cathode 2 will move increases. For example, there is a high possibility that the cathode 2 is displaced (rotated) in the rotation direction due to the weight balance between the one end portion side and the other end portion side of the second portion 12. According to the present embodiment, the concave portion 30 is formed in the heater 5, and at least a part of the second portion 12 is disposed in the concave portion 30, so that the position of the cathode 2 is fixed well.

  Further, according to the present embodiment, the heater 5 can support the cathode 2 such that the center of the electron emission surface 8 and the axis J continue to coincide, for example. Further, the heater 5 can support the cathode 2 so that the electron emission surface 8 is not inclined with respect to the XY plane. Therefore, for example, a change in the traveling direction of the electron beam is suppressed. Further, since the contact area between the cathode 2 and the heater 5 is large, the cathode 2 is efficiently heated by the heater 5. Further, since the contact area between the cathode 2 and the heater 5 is large, even if a part of the cathode 2 is consumed due to heating or the like, the cathode 2 and the heater 5 can be kept in contact for a long time. Therefore, a decrease in the performance of the electron gun 1 is suppressed, and the life of the electron gun 1 can be extended and the reliability can be improved.

Second Embodiment
A second embodiment will be described. In the following description, the same or equivalent components as those in the above-described embodiment are denoted by the same reference numerals, and the description thereof is simplified or omitted.

  FIG. 6 is a perspective view showing an example of a heater 5B having a recess 30B. FIG. 7 is a cross-sectional view showing an example of a state in which the second portion 12 is supported by the two heaters 5B. The recess 30B of the heater 5B has an inner surface 35B. The inner surface 35B is parallel to the XZ plane, the first inner surface 351B parallel to the XZ plane, the second inner surface 352B facing the first inner surface 351B via the gap, and the YZ plane, and the first inner surface 351B. And a third inner surface 353B connecting the second inner surface 352B. In the present embodiment, the recess 30B includes a so-called square groove. As shown in FIG. 7, the two heaters 5 </ b> B support the second portion 12. The inner surface 35B of the first heater 51B is disposed on the + X side with respect to the axis J. The inner surface 35B of the second heater 52B is disposed on the −X side with respect to the axis J. The inner surface 35B of the first heater 51B includes a part 401 on the side surface 145 on the −Y side from the axis J, a part 402 on the side surface 145 on the + Y side from the axis J, and a part 405 between the part 401 and the part 402. To touch. The inner surface 35B of the second heater 52B includes a part 403 on the side surface 145 on the + Y side from the axis J, a part 404 on the side surface 145 on the −Y side from the axis J, and a part 406 between the part 403 and the part 404. To touch. The inner surface 35B is in line contact with the side surface 145 in each of the portion 401, the portion 402, the portion 403, the portion 404, the portion 405, and the portion 406. In the present embodiment, the inner surface 35B may not be in contact with at least one of the parts 401 to 406. For example, the inner surface 35B may not contact one or both of the part 405 and the part 406. Also in the example shown in FIGS. 6 and 7, the change in the position of the cathode 2 in the six directions of the X axis, the Y axis, the Z axis, θX, θY, and θZ is suppressed.

  FIG. 8 is a cross-sectional view showing an example of a state in which the second portion 12 is supported by the two heaters 5C. As shown in FIG. 8, the inner surface 35 </ b> C of the recess 30 </ b> C of the heater 5 </ b> C may come into contact (line contact) with the portions 401 to 410 of the side surface 145. Part 401 to part 410 are arranged so as to surround axis J. Also in the example illustrated in FIG. 8, changes in the position of the cathode 2 in the six directions of the X axis, the Y axis, the Z axis, θX, θY, and θZ are suppressed.

  FIG. 9 is a cross-sectional view showing an example of a state in which the second portion 12 is supported by two heaters 5D. As shown in FIG. 9, almost the entire region of the inner surface 35D of the recess 30D of the heater 5D may be in contact with the side surface 145. The shapes of the recess 30D and the second portion 12 are determined so that almost the entire area of the inner surface 35D is in contact with the side surface 145. Since the contact area between the heater 5D and the second portion 12 is large, a large frictional force can be obtained. Further, the cathode 2 is efficiently heated by the heater 5D. Also in the example illustrated in FIG. 9, the change in the position of the cathode 2 in the six directions of the X axis, the Y axis, the Z axis, θX, θY, and θZ is suppressed.

<Third Embodiment>
A third embodiment will be described. FIG. 10 is a perspective view showing an example of the heater 5E according to the present embodiment. FIG. 11 is a cross-sectional view showing an example of a state in which the second portion 12 is supported by two heaters 5E. The heater 5E has a recess 30E. The inner surface 35E of the recess 30E includes a concave surface. The inner surface 35E includes a curved surface. The inner surface 35E is parallel to the Z axis (axis J). The inner surface 35E is disposed at a part around the axis J.

  As shown in FIG. 11, the curvature of the inner surface 35 </ b> E is smaller than the curvature of the side surface 145 of the second portion 12 in the XY plane. A part of the inner surface 35E comes into contact with the side surface 145. Between the first heater 51E and the second heater 52E, a first gap 41E in which the second portion 12 is disposed and a second gap 42E in which the second portion 12 is not disposed are formed. The second gap 42E is formed on both sides (+ Y side and −Y side) of the first gap 41E in the Y-axis direction. With respect to the X-axis direction, the dimension W2 of the second gap 42E is smaller than the dimension W1 of the first gap 41E.

  Also in the present embodiment, the change in the position of the cathode 2 in the six directions of the X axis, the Y axis, the Z axis, θX, θY, and θZ is suppressed. Note that the force by which the first heater 51E and the second heater 52E sandwich the second portion 12 may be increased within the range of elastic deformation of the first heater 51E and the second heater 52E. For example, the first heater 51E and the second heater 52E may be pressed against the second portion 12 within the range of elastic deformation so that the contact area between the inner surface 35E and the side surface 145 is increased. Further, the first heater 51E and the second heater 52E may sandwich the second portion 12 within a range of elastic deformation so that the support of the second portion 12 by the first heater 51E and the second heater 52E is stabilized. .

<Fourth embodiment>
A fourth embodiment will be described. FIG. 12 is a perspective view showing an example of a state in which the second portion 12F of the cathode 2F is supported by the two heaters 5F according to the present embodiment. FIG. 13 is a perspective view showing an example of the heater 5F according to the present embodiment.

  As shown in FIG. 12, in the present embodiment, the surface of the second portion 12F is substantially parallel to the Z axis (axis J) and intersects the Z axis with a side surface 145F disposed around the axis J. A first surface 151 and a second surface 152 intersecting the Z axis are included. The phrase “substantially parallel to the Z axis (axis J)” includes a state of being completely parallel to the Z axis (axis J). Further, the phrase “substantially parallel to the Z axis (axis J)” includes a state in which the axis is inclined at, for example, 1 degree to 10 degrees with respect to the Z axis (axis J). The side surface 145F includes a first side surface 153 and a second side surface 14 disposed on each of one side (+ Z side) and the other side (−Z side) of the first side surface 153 with respect to the Z-axis direction. The first side surface 153 is substantially parallel to the Z axis (axis J) and is disposed around the axis J. The second side surface 14 is substantially parallel to the Z axis (axis J) and is disposed around the axis J. Regarding the radial direction with respect to the axis J, the distance between the axis J and the first side surface 153 is shorter than the distance between the axis J and the second side surface 14. That is, in the second portion 12 </ b> F, the portion including the first side surface 153 is thinner than the portion including the second side surface 14. In other words, the outer shape of the first side surface 153 is smaller than the outer shape of the second side surface 14 in the XY plane.

  The first surface 151 is arranged so as to connect the second side surface 14 on the + Z side of the first side surface 153 and the first side surface 153. In the present embodiment, the first surface 151 is orthogonal to the Z axis. The first surface 151 is parallel to the XY plane. The first surface 151 faces the −Z direction. The second surface 152 is disposed so as to connect the first side surface 153 and the second side surface 14 on the −Z side of the first side surface 153. In the present embodiment, the second surface 152 is orthogonal to the Z axis. The second surface 152 is parallel to the XY plane. The second surface 152 faces the + Z direction. The first surface 151 and the second surface 152 are opposed to each other through a gap. The first surface 151 and the second surface 152 are parallel. In the XY plane, each of the first surface 151 and the second surface 152 has an annular shape (ring shape). One or both of the first surface 151 and the second surface 152 may be inclined with respect to the XY plane. Note that one or both of the first surface 151 and the second surface 152 may include a curved surface.

  In the present embodiment, the second portion 12F has a recess 10F. The recess 10F is formed so as to surround the axis J. The recess 10F has an inner surface 15F. The inner surface 15F includes a first surface 151, a second surface 152, and a first side surface 153.

  As shown in FIGS. 12 and 13, the heater 5F has a recess 30F in which at least a part of the second portion 12F is disposed. The recess 30F has an inner surface 35F. In the present embodiment, the recess 30F includes a so-called square groove. The recess 30F may include a so-called triangular groove.

  The heater 5F is disposed outside the recess 30F (inner surface 35F), and includes a first outer surface 37F that contacts at least a part of the first surface 151 and a second outer surface 38F that contacts at least a part of the second surface 152. Have. The first outer surface 37F faces the + Z direction. The first outer surface 37F is parallel to the XY plane. The second outer surface 38F faces the −Z direction. The second outer surface 38F is parallel to the XY plane. The first and second outer surfaces 37F and 38F of the heater 5F that can come into contact with at least a part of the cathode 2F function as support surfaces that support the cathode 2F. One or both of the first outer surface 37F and the second outer surface 38F may be inclined with respect to the XY plane. One or both of the first outer surface 37F and the second outer surface 38F may include a curved surface.

  In the present embodiment, the heater 5F has a convex portion 36F that is at least partially disposed in the concave portion 10F of the second portion 12F. A first outer surface 37F facing the + Z direction and a second outer surface 38F facing the −Z direction are arranged on the convex portion 36F. The convex portion 36F has a third outer surface 39F that connects the first outer surface 37F and the second outer surface 38F.

  As shown in FIG. 12, at least a part of the inner surface 35 </ b> F of the recess 30 </ b> F is in contact with the second side surface 14. The inner surface 35F and the second side surface 14 are in line contact, for example. In addition, at least a part of the convex part 36F of the heater 5F is arranged in the concave part 10F of the second part 12F in a state in which at least a part of the second part 12F is arranged in the concave part 30F. In a state where at least a part of the convex portion 36F is disposed in the concave portion 10F, the first outer surface 37F and the first surface 151 are in contact with each other, and the second outer surface 38F and the second surface 152 are in contact with each other. In a state where at least a part of the convex part 36F is disposed in the concave part 10F, at least a part of the convex part 36F (heater 5F) and the first side surface 153 come into contact (line contact).

  As described above, according to the present embodiment, the second side surface 14 comes into contact with the inner surface 35F of the recess 30F, so that the displacement of the cathode 2F in at least the XY plane (displacement in the X axis, Y axis, and θZ directions). Is suppressed. Further, the displacement of the cathode 2F in the θX and θY directions is also suppressed. Further, when the first surface 151 is in contact with the first outer surface 37F of the heater 5F and the second surface 152 is in contact with the second outer surface 38F of the heater 5F, displacement of the cathode 2F in at least the Z-axis direction is suppressed. Further, the displacement of the cathode 2F in the θX and θY directions is also suppressed. Further, the displacement of the cathode 2F is also suppressed when at least a part of the heater 5F (the convex portion 36F) is in contact with the first side surface 153.

  In the present embodiment, the convex portion 36F disposed in the concave portion 10F may not be in contact with the first side surface 153.

  FIG. 14 is a perspective view showing an example of a state in which the second portion 12F of the cathode 2F is supported by the two heaters 5G according to the present embodiment. FIG. 15 is a perspective view showing an example of the heater 5G according to the present embodiment.

  A recess 10F is formed in the second portion 12F of the cathode 2F. The surface of the second portion 12F includes a side surface 145F including the first side surface 153 and the second side surface 14, and a first surface 151 and a second surface 152 that intersect the Z axis. The inner surface 15F of the recess 10F includes a first surface 151, a second surface 152, and a first side surface 153.

  As shown in FIGS. 14 and 15, the heater 5G has a recess 30G in which at least a part of the second portion 12F is disposed. The recess 30G has an inner surface 35G. The inner surface 35G includes a concave surface. The inner surface 35G includes a curved surface.

  The heater 5G is disposed outside the recess 30G (inner surface 35G), and includes a first outer surface 37G that contacts at least a part of the first surface 151 and a second outer surface 38G that contacts at least a part of the second surface 152. Have. Each of the first outer surface 37G and the second outer surface 38G is parallel to the XY plane. Note that one or both of the first outer surface 37G and the second outer surface 38G may be inclined with respect to the XY plane, or may include a curved surface.

  The heater 5G has a convex portion 36G that is at least partially disposed in the concave portion 10F of the second portion 12F. A first outer surface 37G facing the + Z direction and a second outer surface 38G facing the −Z direction are arranged on the convex portion 36G. The convex portion 36G has a third outer surface 39G that connects the first outer surface 37G and the second outer surface 38G.

  As shown in FIG. 14, at least a part of the inner surface 35 </ b> G of the recess 30 </ b> G is in contact with the second side surface 14. The inner surface 35F and the second side surface 14 are in line contact, for example. In addition, at least a part of the convex part 36G of the heater 5G is arranged in the concave part 10F of the second part 12F in a state where at least a part of the second part 12G is arranged in the concave part 30G. In a state where at least a part of the convex portion 36G is disposed in the concave portion 10F, the first outer surface 37G and the first surface 151 are in contact with each other, and the second outer surface 38G and the second surface 152 are in contact with each other. In a state where at least a part of the convex part 36G is arranged in the concave part 10F, at least a part of the third outer surface 39G of the convex part 36G and the first side surface 153 come into contact (line contact).

  Also in the example shown in FIGS. 14 and 15, the displacement of the cathode 2F is suppressed. 14 and 15, the convex portion 36G (third outer surface 39G) disposed in the concave portion 10F may not be in contact with the first side surface 153.

<Fifth Embodiment>
A fifth embodiment will be described. FIG. 16 is a perspective view showing an example of a state in which the second portion 12H of the cathode 2H is supported by the two heaters 5H according to the present embodiment. FIG. 17 is a perspective view showing an example of the heater 5H according to the present embodiment.

  As shown in FIG. 16, in the present embodiment, the surface of the second portion 12H includes a side surface 145H disposed around the axis J and a first surface 151H that intersects the Z axis. The side surface 145H includes a first side surface 153H and a second side surface 14H disposed on one side (+ Z side) and the other side (−Z side) of the first side surface 153H in the Z-axis direction. The first side surface 153H is inclined in the −Z direction toward the outside with respect to the radial direction with respect to the axis J. The first side surface 153H includes a curved surface. The first side surface 153H is disposed around the axis J. The second side surface 14H is substantially parallel to the Z axis (axis J) and is disposed around the axis J. Regarding the radial direction with respect to the axis J, the distance between the axis J and the first side surface 153H is shorter than the distance between the axis J and the second side surface 14H.

  The first surface 151H is disposed so as to connect the second side surface 14H on the + Z side of the first side surface 153H and the first side surface 153H. In the present embodiment, the first surface 151H is orthogonal to the Z axis. The first surface 151H is parallel to the XY plane. The first surface 151H faces the −Z direction. In the XY plane, the first surface 151H has an annular shape (ring shape). The −Z side end of the first side surface 153H and the −Z side second side surface 14H of the first side surface 153H are connected.

  In the present embodiment, a recess 10H that surrounds the axis J is formed in the second portion 12H. The recess 10H has an inner surface 15H. The inner surface 15H includes a first surface 151H and a first side surface 153H.

  As shown in FIGS. 16 and 17, the heater 5H has a recess 30H in which at least a part of the second portion 12H is disposed. The recess 30H has an inner surface 35H. The inner surface 35H includes a curved surface. The inclination angle of the first side surface 153H with respect to the axis J is equal to the inclination angle of the inner surface 35H with respect to the axis J. The first side surface 153H can contact almost the entire region of the inner surface 35H.

  The heater 5H is disposed outside the recess 30H (inner surface 35H) and has an outer surface 37H with which at least a part of the first surface 151H contacts. The outer surface 37H faces the + Z direction. The outer surface 37H is parallel to the XY plane.

  As shown in FIG. 16, almost the entire area of the inner surface 35H and the first side surface 153H are in contact with each other, and at least a part of the outer surface 37H and the first surface 151H are in contact with each other. The shape of the concave portion 30H and the second portion 12H (the concave portion 10H) is determined so that the inner surface 35H and the first side surface 153H are in contact with each other, and the outer surface 37H and the first surface 151H are in contact with each other.

  As described above, in the present embodiment, since the inner surface 35H and the first side surface 153H are in contact with each other, and the outer surface 37H and the first surface 151H are in contact with each other, the X axis, Y axis, Z axis, θX, θY, And the displacement of the cathode 2H in the six directions of θZ is suppressed.

  In the present embodiment, the entire area of the inner surface 35H may not be in contact with the first side surface 153H. A partial region of the inner surface 35H may be in contact with the first side surface 153H, and a partial region of the inner surface 35H may be separated from the first side surface 153H.

  FIG. 18 is a diagram illustrating an example of the heater 5J according to the present embodiment. The heater 5J can support the second portion 12H of the cathode 2H shown in FIG. The second portion 12H is sandwiched and supported by the two heaters 5J. The heater 5J has a recess 30J in which at least a part of the second portion 12H is disposed. The recess 30J has an inner surface 35J. The inner surface 35J includes a first inner surface 351J and a second inner surface 352J that faces in a different direction from the first inner surface 351J. Each of the first inner surface 351J and the second inner surface 352J is a flat surface (flat). The inclination angle of the first side surface 153H with respect to the axis J, the inclination angle of the first inner surface 351J with respect to the axis J, and the inclination angle of the second inner surface 352J with respect to the axis J are equal. The first inner surface 351J and the second inner surface 352J can be in contact with the first side surface 153H at the same time. The first inner surface 351J and a part of the first side surface 153H are in line contact. The second inner surface 352J and a part of the first side surface 153H are in line contact. The displacement of the cathode 2H is also suppressed by supporting the second portion 12H using the heater 5J shown in FIG.

<Sixth Embodiment>
A sixth embodiment will be described. FIG. 19 is a cross-sectional view showing an example of a state in which the cathode 2Hb is supported by two heaters 5H. The cathode 2Hb has a recess 10H as described with reference to FIG. The heater 5H has a recess 30H as described with reference to FIGS.

  In the present embodiment, a support member 19 that supports the cathode 2Hb is provided. The support member 19 supports a portion different from the portion supported by the heater 5H of the cathode 2Hb. The heater 5H contacts the inner surface 15H of the recess 10H and supports the inner surface 15H. That is, the portion of the cathode 2Hb supported by the heater 5H is the inner surface 15H (recessed portion 10H). The support member 19 supports a part of the cathode 2Hb different from the inner surface 15H.

  The support member 19 supports the second portion 12Hb. The support member 19 supports a part of the second portion 12Hb different from the inner surface 15H. The support member 19 does not contact the first portion 11. At least a part of the support member 19 is disposed so as to face the lower surface 21 of the second portion 12Hb facing the direction opposite to the electron emission surface 8. The support member 19 may be disposed so as to contact the lower surface 21.

  In the present embodiment, the second portion 12Hb has a hole 20. In addition, a hole part may be called a recessed part and may be called an opening. The hole 20 is formed in the lower surface 21. A part of the support member 19 is disposed in the hole 20. The support member 19 contacts the inner surface of the hole 20 and supports the inner surface of the hole 20.

  In the present embodiment, the support member 19 is a conical member. The shape of the hole 20 is determined such that at least a part of the inner surface of the hole 20 is in contact with the support member 19.

  In the present embodiment, the cathode 2Hb is supported by the two heaters 5H and the support member 19. Therefore, the position of the cathode 2Hb is fixed well. In the present embodiment, the support member 19 is disposed in the hole 20 formed in the lower surface 21. Thereby, the support member 19 can suppress the movement of the cathode 2Hb at least in the XY plane.

  In the present embodiment, a plurality of support members 19 may be provided. Each of the plurality of portions of the cathode 2Hb may be supported by the plurality of support members 19. The hole 20 may not be formed in the cathode 2Hb. The support member 19 may support the lower surface 21 in which the hole 20 is not formed.

  In the present embodiment, the cathode 2Hb is supported by the support member 19. However, the cathode 2 described with reference to FIG. 4 and the like may be supported by the heater and the support member 19, and FIG. The cathode 2F described with reference to FIG. 5 may be supported by the heater and the support member 19.

<Seventh embodiment>
A seventh embodiment will be described. FIG. 20 is a diagram illustrating an example of a state in which the cathode 2 </ b> K is supported by the two heaters 5. The cathode 2K includes a first portion 11K having an electron emission surface 8, a second portion 12K having an outer shape in the XY plane perpendicular to the axis J smaller than the first portion 11K, and an outer shape in the XY plane having a second portion 12K. Larger third portion 13K. The second portion 12K does not have a recess. The heater 5 has the recessed part 30 which was demonstrated with reference to FIG. At least a part of the second portion 12 </ b> K is disposed in the recess 30 of the heater 5. The first portion 11K is connected to one end (the end on the + Z side) of the second portion 12K. The third portion 13K is connected to the other end (−Z side end) of the second portion 12K. Each of the first portion 11K and the third portion 13K has a plate shape. In the XY plane, the outer shape of the first portion 11K and the outer shape of the third portion 13K are substantially equal. With respect to the Z-axis direction, the dimensions of the first portion 11K and the third portion 13K are substantially equal. The center of gravity G of the cathode 2K coincides with the center of the second portion 12K in the Z-axis direction. The first heater 51 and the second heater 52 are supported so as to sandwich the center of the second portion 12K in the Z-axis direction. The cathode 2K is supported by the first heater 51 and the second heater 52 so that the center of gravity G of the cathode 2K is located between the first heater 51 and the second heater 52.

  The center of gravity G of the cathode 2K is located between the first contact surface of the cathode 2K with which the first heater 51 contacts and the second contact surface of the cathode 2 with which the second heater 52 contacts. The first contact surface is a surface (action surface, support surface) on which a force from the first heater 51 acts. The second contact surface is a surface on which the force from the second heater 52 acts. The center of gravity G is located between the center (support point) of the first contact surface and the center (support point) of the second contact surface.

  In the present embodiment, the dimension Hc of the second portion 12 disposed on the + Z side with respect to the first heater 51 and the second heater 52 and the first dimension disposed on the −Z side with respect to the first heater 51 and the second heater 52. The dimension Hd of the two portions 12 is substantially equal.

  In the example shown in FIG. 20, the first portion 11K is disposed on one end portion side of the second portion 12K, the third portion 13K is disposed on the other end portion side of the second portion 12K, The balance of mass (weight) with the end side is improved. Further, the cathode 2K is supported by the first heater 51 and the second heater 52 so that the center of gravity G of the cathode 2K is positioned between the first heater 51 and the second heater 52, so that even if an external force is applied. The displacement (rotation, inclination) of the cathode 2K with respect to the rotation direction (for example, the θX direction) is suppressed. When the cathode 2K is supported by the first heater 51 and the second heater 52 so that the center of gravity G of the cathode 2K is positioned between the first heater 51 and the second heater 52, the dimension of the cathode 2K in the Z-axis direction. Is suppressed from increasing. For example, an increase in the dimension Hd is suppressed.

  In the example shown in FIG. 20, the surface 22 of the third portion 13K facing the direction opposite to the electron emission surface 8 of the first portion 11K can be used as the electron emission surface. For example, when the electron emission surface 8 of the first portion 11K deteriorates, the surface 22 of the third portion 13K may be used as the electron emission surface.

  Note that, as described in the first to sixth embodiments, the cathode having no third portion is also provided with two heaters so that the center of gravity G of the cathode is located between the two heaters. By supporting, the displacement of the cathode is suppressed.

  The cathode 2K shown in FIG. 20 may be supported by the support member 19 described with reference to FIG. When the cathode 2K is supported by the support member 19, a hole 20 in which at least a part of the support member 19 is disposed may be formed on the surface 22 of the third portion 13K, or the hole 20 may not be formed. Also good.

  In each of the embodiments described above, the second portion supported by the heater may have a prismatic shape (for example, a quadrangular prism shape). That is, the outer shape of the second portion may be a polygon (for example, a quadrangle) in the XY plane.

<Eighth Embodiment>
An eighth embodiment will be described. FIG. 21 is a front view illustrating an example of the support electrode 6L, the heater 5L, and the cathode 2L according to the present embodiment. FIG. 22 is a BB line arrow view of FIG. FIG. 23 is a perspective view illustrating an example of the support electrode 6L and the heater 5L according to the present embodiment. As shown in FIG. 1 and the like, the support electrode may be longer (larger) than the heater in the Z-axis direction. In the present embodiment, a part of the support electrode connected to the heater is schematically illustrated.

  In the present embodiment, the cathode 2L has a rod shape. The cathode 2L includes a portion (second portion) 12L supported by the heater 5L, and a tip portion 111L which is disposed on the + Z side of the portion 12L and whose outer shape in the XY plane is smaller than that of the portion 12L. The tip portion 111L has a conical shape. The tip portion 111L has an electron emission surface 8L. The electron emission surface 8L includes a slope inclined with respect to the axis J. The electron emission surface 8L may include a curved surface. The portion 12L of the cathode 2L is cylindrical. The electron emission surface 8L may be a plane parallel to the XY plane. The cathode 2L may have the first part and the second part as described in the above embodiments. The cathode 2L may have a recess in which at least a part of the heater is disposed as described with reference to FIGS. The cathode 2L (part 12L) may have a prismatic shape (for example, a quadrangular prism shape). That is, the outer shape of the cathode 2L may be a polygon (for example, a quadrangle) in the XY plane.

  The heater 5L that supports the cathode 2L does not have a recess. The support surface 50 of the heater 5L facing the cathode 2L is flat (flat). The cathode 2L is supported by being sandwiched between two heaters 5L. The heater 5L may be formed with a recess in which at least a part of the cathode is disposed as described in the above embodiments. In other words, the support surface 50 of the heater 5L may include the inner surface of the recess as described in the above embodiments, or may include the outer surface of the outer side of the recess.

  The support electrode 6L has a support surface 60 that the heater 5L faces. At least a part of the support surface 60 can contact the heater 5L. The support surface 60 of the support electrode 6 </ b> L includes a first support surface (first region) 601 and a second support surface (second region) 602 that faces a direction different from the first support surface 601. Each of the first support surface 601 and the second support surface 602 can contact the heater 5L. The first support surface 601 and the second support surface 602 can be in contact with the heater 5L at the same time.

  The first support surface 601 and the second support surface 602 are arranged in the Y-axis direction. Each of the first support surface 601 and the second support surface 602 is a flat surface (flat). The outer shape of the first support surface 601 and the outer shape of the second support surface 602 are substantially equal. In the present embodiment, the outer shapes of the first support surface 601 and the second support surface 602 are each rectangular. The first support surface 601 and the second support surface 602 are each disposed substantially parallel to the Z axis (axis J). The first support surface 601 and the second support surface 602 are each inclined with respect to the XZ plane (YZ plane). The angle formed by the first support surface 601 and the second support surface 602 is smaller than 180 degrees.

  The center (center) of the support surface 60 is farther from the heater 5 </ b> L than the peripheral region of the support surface 60. Support surface 60 includes a concave surface that is recessed with respect to heater 5L. The support electrode 6L has a recess 63 that is recessed with respect to the heater 5L. The inner surface of the recess 63 includes a support surface 60.

  The heater 5L has a facing surface 70 to which the support surface 60 can face. The facing surface 70 faces in the opposite direction of the support surface 50. The support surface 60 is in contact with at least a part of the facing surface 70. The support surface 60 supports the facing surface 70. The facing surface 70 may be referred to as a supported surface 70 or a contact surface 70. In the present embodiment, the shapes of the heater 5L and the support electrode 6L are determined so that almost the entire region of the support surface 60 and the facing surface 70 are in contact with each other. The facing surface 70 includes a first facing surface 701 that contacts the first supporting surface 601 of the supporting surface 60 and a second facing surface 702 that contacts the second supporting surface 602.

  The center (center) of the facing surface 70 is closer to the support electrode 6 </ b> L than the peripheral region of the facing surface 70. The facing surface 70 includes a convex surface that protrudes with respect to the support electrode 6L. The heater 5L has a protrusion 73 that protrudes with respect to the support electrode 6L. The outer surface of the convex portion 73 includes a facing surface 70.

  As shown in FIGS. 21 and 22, the convex portion 73 is disposed in the concave portion 63, the first support surface 601 and the first opposing surface 701 are in contact, and the second support surface 602 and the second opposing surface 702 are in contact. To do. The two support electrodes 6L support the two heaters 5L and the cathode 2L sandwiched between the two heaters 5L.

  As described above, according to the present embodiment, the support surface 60 of the support electrode 6L that contacts the heater 5L faces the first support surface 601 and the second support surface 602 in a direction different from the first support surface 601. Since each of the first and second support surfaces 601 and 602 contacts the heater 5L, the change in the position of the heater 5L with respect to the support electrode 6L is suppressed. For example, when the first support surface 601 of the support electrode 6L comes into contact with the heater 5L, a change in the position of the heater 5L with respect to the direction intersecting the first support surface 601 is suppressed. When the second support surface 602 of the support electrode 6L contacts the heater 5L, a change in the position of the heater 6L with respect to the direction intersecting the second support surface 602 is suppressed. In the present embodiment, the displacement of the heater 5L with respect to at least the X-axis, Y-axis, θX, θY, and θZ directions is suppressed. Further, since the contact area between the support surface 60 and the opposed surface 70 is large, the displacement of the heater 5L in the Z-axis direction is also suppressed by the frictional force between the support surface 60 and the opposed surface 70. That is, in the present embodiment, the displacement of the heater 5L with respect to the six directions of the X axis, the Y axis, the Z axis, θX, θY, and θZ is suppressed. Further, by suppressing the change in the position of the heater 5L, the change in the position of the cathode 2L supported by the heater 5L is also suppressed.

  FIG. 24 is a perspective view showing an example of the support electrode 6M and the heater 5M. The support electrode 6M has a recess 63M. The heater 5M has a convex portion 73M. The inner surface of the recess 63M includes a support surface 60M of the support electrode 6M that supports the heater 5M. The outer surface of the convex portion 73M includes a facing surface 70M of the heater 5M that contacts at least a part of the support surface 60M.

  The support surface 60M of the support electrode 6M has a first support surface 601M, a second support surface 602M facing in a different direction from the first support surface 601M, and a direction different from the first support surface 601M and the second support surface 602M. And a third support surface 603M facing. Each of the first support surface 601M, the second support surface 602M, and the third support surface 603M can be in contact with the heater 5M at the same time.

  The first support surface 601M, the second support surface 602M, and the third support surface 603M are arranged in the Y-axis direction. The third support surface 603M is disposed between the first support surface 601M and the second support surface 602M. The first support surface 601M, the second support surface 602M, and the third support surface 603M are each flat (flat). The outer shapes of the first support surface 601M, the second support surface 602M, and the third support surface 603M are each rectangular. The first support surface 601M, the second support surface 602M, and the third support surface 603M are each disposed substantially parallel to the Z axis (axis J). The first support surface 601M and the second support surface 602M are inclined with respect to the XZ plane (YZ plane). The third support surface 603M is parallel to the YZ plane.

  The opposing surface 70M of the heater 5M includes a first opposing surface 701M, a second opposing surface 702M, and a third opposing surface 703M that are in contact with the first supporting surface 601M, the second supporting surface 602M, and the third supporting surface 603M, respectively. . The shapes of the heater 5M and the support electrode 6M are determined so that almost the entire region of the support surface 60M comes into contact with the opposing surface 70M. The convex part 73M is arrange | positioned at the recessed part 63M, and each of the opposing surface 701M contacts the 1st opposing surface 701M, the 2nd opposing surface 702M, and the 3rd opposing surface 703M. Thereby, the support electrode 6M can support the heater 5M and the cathode 2L while suppressing the displacement of the heater 5M.

  FIG. 25 is a perspective view showing an example of the support electrode 6N and the heater 5N. The support electrode 6N has a recess 63N. The heater 5N has a convex portion 73N. The support surface 60N of the support electrode 6N that supports the heater 5N includes an inner surface 163 of the recess 63N and an outer surface 164 outside the recess 63N. In the example shown in FIG. 25, the inner surface 163 of the recess 63N includes a first inner surface 601N that is parallel to the XZ plane, a second inner surface 602N that is parallel to the XY plane and faces the first inner surface 601N via a gap, A third inner surface 603N connecting the first inner surface 601N and the second inner surface 602N. The third inner surface 603N is parallel to the YZ plane. The outer surface 164 is disposed on each of the + Y side and the −Y side of the recess 63N. The outer surface 164 is parallel to the YZ plane. The opposing surface 70N of the heater 5N that contacts the support surface 60N includes an outer surface 165 of the convex portion 73N and a surface 166 disposed on the + Y side and the −Y side with respect to the convex portion 73N. A convex portion 73N is disposed in the concave portion 63N. Thereby, the inner surface 163 of the recessed part 63N and the outer surface 165 of the convex part 73N contact. Further, the outer surface 164 and the surface 166 are in contact with each other in a state where the convex portion 73N is disposed in the concave portion 63N. Also in the example shown in FIG. 25, the support electrode 6N can support the heater 5N and the cathode 2L while suppressing the displacement of the heater 5N.

  FIG. 26 is a perspective view showing an example of the support electrode 6P and the heater 5P. As shown in FIG. 26, the support surface 60P of the support electrode 6P includes a curved surface. The support surface 60P is parallel to the Z axis (axis J). The support surface 60P is bent so as to surround the axis J. The support surface 60P has a plurality of regions facing different directions. The heater 5P supported by the support electrode 6P has a facing surface 70P that can come into contact with almost the entire region of the support surface 60P. Also in the example shown in FIG. 26, the support electrode 6P can support the heater 5P and the cathode 2L while suppressing the displacement of the heater 5P.

  FIG. 27 is a perspective view showing an example of the support electrode 6Q and the heater 5Q. As shown in FIG. 27, the support surface 60Q of the support electrode 6Q includes a curved surface. The heater 5Q has an opposing surface 70Q that can come into contact with almost the entire region of the support surface 60Q. The facing surface 70Q may be a part of the surface of the sphere or a part of the surface of the ellipsoid. Also in the example shown in FIG. 27, the support electrode 6Q can support the heater 5Q and the cathode 2L while suppressing the displacement of the heater 5Q.

  In the example shown in FIG. 23, the first support surface 601 and the second support surface 602 are arranged in the Y-axis direction. As shown in FIG. 28, the first support surface 601 and the second support surface 602 may be arranged in the Z-axis direction. Since the heater 5L has the opposing surface 70 that can come into contact with the support surface 60 shown in FIG. 28, the displacement of the heater 5L is suppressed. Similarly, in the support electrode 60M shown in FIG. 24, the support electrode 60M is provided so that the first support surface 601M, the second support surface 602M, and the third support surface 603M are arranged in the Z-axis direction. Good. In the support electrode 60N shown in FIG. 25, the support electrode 60N may be provided so that the outer surface 164 is disposed on each of the + Z side and the −Z side of the recess 63N.

  As shown in FIGS. 29 and 30, the support surface 60R of the support electrode 6R and the support surface 60S of the support electrode 6S may include convex surfaces. In the example shown in FIG. 29, the support surface 60R includes two planes facing different directions. The support surface 60R may include three or more planes facing different directions. In the example shown in FIG. 30, the support surface 60S includes a curved surface. When the support surface (60R, etc.) includes a convex surface, the support electrode (6R, etc.) can be used as the heater because the opposing surface of the heater facing the support surface includes a concave surface that can contact the support surface (60R, etc.). Can be well supported.

<Ninth Embodiment>
A ninth embodiment will be described. FIG. 31 is a diagram illustrating an example of the heater 5Hb and the support electrode 6S according to the present embodiment. As shown in FIG. 31, the support electrode 6S that supports the heater 5Hb may have a support surface 60S having at least two regions facing different directions as described in the eighth embodiment. The heater 5Hb has a recess 30H as described with reference to FIGS. 16 and 17, for example, and can support the cathode 2Hb as described with reference to FIG. The cathode 2Hb is supported by the heater 5Hb and the support member 19. Thus, you may combine each requirement of the above-mentioned 1st-8th embodiment. In the example shown in FIG. 31, at least a part of the support surface 60 </ b> S of the support electrode 6 </ b> S is inclined outward in the −Z direction with respect to the radial direction with respect to the axis J. The heater 5Hb supported by the inclined support surface 60S may apply a force in the −Z direction to the cathode 2Hb. The support member 19 supports the cathode 2Hb on the −Z side with respect to the heater 5Hb, and the displacement of the cathode 2Hb is suppressed.

<Tenth Embodiment>
A tenth embodiment will be described. FIG. 32 is a diagram illustrating an example of the radiation generation apparatus 100 according to the present embodiment. The radiation generating apparatus 100 includes an electron gun 1 and a target 102 to which an electron beam from the electron gun 1 is irradiated. The electron gun 1 includes at least a part of the cathode (such as 2), the heater, and the support electrode described in the above embodiments. The radiation generation apparatus 100 includes an electron beam acceleration device 101 that accelerates an electron beam emitted from the electron gun 1. The target 102 is disposed at the end portion of the electron beam accelerator 101. The target 102 includes, for example, tungsten, and generates X-rays by irradiation with an electron beam. X-rays generated from the target 102 are focused by, for example, a collimator and irradiated onto the object.

  According to the present embodiment, the displacement of at least one of the cathode and the heater is suppressed, and the change in the traveling direction of the electron beam emitted from the electron gun 1 is suppressed. Is done.

  Note that the electron gun 1 according to the present embodiment may be used in a radiation therapy apparatus, may be used in an industrial X-ray CT scan apparatus, or may be used in an electron microscope. For example, the electron gun 1 according to the present embodiment may be used in a radiotherapy apparatus including a rotating gantry and a couch as disclosed in JP 2007-267971 A.

DESCRIPTION OF SYMBOLS 1 Electron gun 2 Cathode 4 Anode 5 Heater 6 Support electrode 8 Electron emission surface 10 Recess 11 1st part 12 2nd part 13K 3rd part 14 2nd side surface 15 Inner surface 19 Support member 20 Hole 30 Recess 35 Inner surface 51 First heater 52 Second heater 60 Support surface 61 First support electrode 62 Second support electrode 70 Opposing surface 100 Radiation generator 102 Target 145 Side surface 151 First surface 152 Second surface 153 First side surface 601 First support surface J-axis

Claims (10)

A first portion capable of emitting thermoelectrons and having an electron emission surface orthogonal to a predetermined axis, and a cathode including a second portion whose outer shape in a plane orthogonal to the predetermined axis is smaller than the first portion;
A heater for supporting the second part,
The heater is an electron gun having a recess in which at least a part of the second portion is disposed. The heaters are arranged on one side and the other side of the predetermined axis with respect to a direction parallel to the first axis in a plane perpendicular to the predetermined axis, and support two heaters sandwiching the second portion. Including
The inner surface of the recess has at least part of the surface of the second portion on one side of the predetermined axis and the second on the other side in a direction parallel to the second axis orthogonal to the first axis in the surface. The electron gun according to claim 1, wherein the electron gun contacts at least a part of the surface of the part. The second portion is arranged around the predetermined axis substantially parallel to the predetermined axis, and intersects with a first surface contacting at least a part of the inner surface of the recess and an axis parallel to the predetermined axis. A second surface,
3. The electron gun according to claim 1, wherein the heater has an outer surface that is disposed outside the recess and is in contact with at least a part of the second surface. The second part is rod-shaped, one end of the second part is connected to the first part,
The said cathode is connected to the other end part of the said 2nd part, The external shape in the surface orthogonal to the said predetermined axis contains the 3rd part larger than the said 2nd part. The electron gun according to the item. A support electrode for supporting the heater;
The support surface of the support electrode includes a first region in contact with the heater and a second region in a direction different from the first region and in contact with the heater. An electron gun according to claim 1. A cathode from which thermionic electrons are emitted;
A heater for supporting the cathode;
A support electrode for supporting the heater,
The support surface of the support electrode is an electron gun including: a first region that contacts the heater; and a second region that faces a direction different from the first region and contacts the heater.   The electron gun according to claim 5, wherein the support surface includes a concave surface.   The electron gun according to any one of claims 1 to 7, further comprising a support member that supports a portion of the cathode that is different from the portion supported by the heater. The second part has a hole,
The electron gun according to claim 8, wherein at least a part of the support member is disposed in the hole. An electron gun according to any one of claims 1 to 9,
A radiation generator comprising: a target irradiated with an electron beam from the electron gun.

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