Rotating anode unit and X-ray generating device

Abstract

The rotating anode unit comprises: a target formed of a first metal material; and a target support body formed of a second metal material in a flat plate shape and having a first and a second surface. The thermal conductivity of the second metal material is higher than the thermal conductivity of the first metal material. A first recess is formed on the first surface in the outer portion of the target support body. The target is arranged in the first recess. A second recess is formed on the second surface in the inner portion of the target support body in a manner to define a flow path for circulating a refrigerant. The thickness of the first region where the first recess is formed is thicker than the thickness of the second region where the second recess is formed.

Description

Technical Field

[0001] One aspect of the present invention relates to a rotating anode unit and an X-ray generating device including the rotating anode unit. Background Art

[0002] An X-ray generating device is known that generates X-rays by causing an electron beam emitted from a cathode to be incident on a rotating target. In such an X-ray generating device, the target is heated by absorption of electrons. As a technique for cooling the target, Japanese Patent No. 5265906 discloses water cooling of a disk-shaped target from the back side to which a shaft is connected.

[0003] Prior art literature

[0004] Patent Literature

[0005] Patent Document 1: Japanese Patent No. 5265906 Summary of the invention

[0006] Problems to be solved by the invention

[0007] In the above-mentioned technology, when the thermal conductivity of the target is low or the thermal conductivity between the target and the shaft is low, the target may not be sufficiently cooled. Therefore, it is considered to improve the cooling performance by forming the portion other than the electron incident portion in the target with a material having a higher thermal conductivity than the electron incident portion. However, sufficient cooling performance cannot be obtained by simply using a material with a high thermal conductivity.

[0008] An object of one aspect of the present invention is to provide a rotating anode unit and an X-ray generator with improved cooling performance.

[0009] Technical means of solving problems

[0010] A rotating anode unit according to one aspect of the present invention comprises: a target formed into an annular shape by a first metal material to constitute an annular electron incident surface; and a target support body formed into a flat plate shape by a second metal material, having a first surface extending approximately perpendicularly to a rotation axis, and a second surface on the opposite side of the first surface; the thermal conductivity of the second metal material is higher than the thermal conductivity of the first metal material; the target support body comprises an outer portion to which the target is fixed, and an inner portion located inside the outer portion and including the rotation axis; a first recess is formed on the first surface of the outer portion; the target is arranged in the first recess, and the electron incident surface of the target is located on the same plane as the first surface; a second recess is formed on the second surface of the inner portion in a manner to define a flow path for circulating a coolant; the thickness of the first region in the outer portion where the first recess is formed is thicker than the thickness of the second region in the inner portion where the second recess is formed.

[0011] In the rotating anode unit, the target support body is formed by a second metal material having a higher thermal conductivity than the thermal conductivity of the first metal material constituting the target. Thus, the cooling performance can be improved. In addition, a first recessed portion in which the target is arranged is formed on the first surface in the outer portion of the target support body, and a second recessed portion defining a flow path for circulating a coolant is formed on the second surface in the inner portion of the target support body. The thickness of the first region in which the first recessed portion is formed in the outer portion is thicker than the thickness of the second region in which the second recessed portion is formed in the inner portion. Thus, the heat capacity of the first region can be increased, and the cooling efficiency of the second region can be improved. As a result, the heat generated by the target can be stored in the first region, and the heat stored in the first region can be efficiently cooled in the second region. Therefore, in the rotating anode unit, the cooling performance is improved. Furthermore, the electron incident surface of the target is located on the same plane as the first surface extending approximately perpendicularly to the rotation axis of the target support body. Thus, the workability of the grinding operation of the electron incident surface and the first surface is improved.

[0012] The difference between the thickness of the second region and the target may be smaller than the difference between the thickness of the first region and the second region. In this case, the cooling efficiency in the second region can be further improved, and the heat generated by the target can be easily transferred to the first region having a large heat capacity.

[0013] The surface roughness Ra of at least one of the bottom surface of the first recess and the surface of the target in contact with the bottom surface may be 1.6 μm or less. In this case, the target and the target support can be brought into suitable contact with each other, and the cooling efficiency can be further improved.

[0014] The surface roughness Ra of the electron incident surface of the target may be 0.5 μm or less. In this case, a large amount of X-rays can be emitted from the target when an electron beam is incident.

[0015] Alternatively, when the target thickness is set to t, the contact width between the target and the bottom surface of the first recessed portion is greater than 2t and less than 8t. In this case, the contact width is greater than 2t, thereby increasing the contact area between the target and the target support, and further improving the cooling efficiency. In addition, the contact width is less than 8t, thereby ensuring the area of ​​the second region, and further improving the cooling efficiency of the second region.

[0016] Alternatively, an insertion hole may be formed on the outer portion to pass through the bottom surface of the first recess and the second surface, and the target may be fixed to the target support body by a fastening member inserted through the insertion hole. In this case, the target and the target support body may be further brought into close contact and fixed.

[0017] The rotary anode unit according to one aspect of the present invention may further include a shaft fixed to the target support from the second surface side and defining the flow path together with the second recess. In this case, the target support can be rotated via the shaft, and the flow path can be defined by the second recess and the shaft.

[0018] The rotary anode unit according to one aspect of the present invention may further include a flow path forming member having a cylindrical portion disposed in the shaft and a flange portion protruding outward from the cylindrical portion, and defining the flow path together with the second recess and the shaft. In this case, the flow path can be defined by the second recess, the shaft, and the flow path forming member.

[0019] An X-ray generating device according to one aspect of the present invention includes the above-mentioned rotating anode unit. In this X-ray generating device, the cooling performance is improved for the above-mentioned reasons.

[0020] Effects of the Invention

[0021] According to one aspect of the present invention, a rotating anode unit and an X-ray generating device having improved cooling performance can be provided. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 It is a block diagram of an X-ray generating device according to an embodiment.

[0023] Figure 2 is a cross-sectional view of a portion of a rotating anode unit.

[0024] Figure 3 This is a front view of the target and the target support.

[0025] Figure 4 It is a bottom view of the target support.

[0026] Figure 5 is along Figure 4 Cross-sectional view of line VV.

[0027] Figure 6 yes Figure 1 A magnified portion of the image.

[0028] Figure 7 This is a front view of the frame of the rotating anode unit.

[0029] Figure 8 It is a cross-sectional view of a target and a target support body according to a modified example. DETAILED DESCRIPTION

[0030] Hereinafter, one embodiment of the present invention will be described in detail with reference to the accompanying drawings. In the following description, the same reference numerals are used for the same or equivalent elements, and repeated descriptions are omitted.

[0031] [X-ray generating device]

[0032] like Figure 1As shown, the X-ray generating device 1 includes an electron gun 2, a rotating anode unit 3, a magnetic lens 4, an exhaust section 5, and a frame 6. The electron gun 2 is arranged in the frame 6 and emits an electron beam EB. The rotating anode unit 3 has a target 31 in the shape of an annular plate. The target 31 is supported in a manner that can rotate around the rotation axis A, and receives the electron beam EB while rotating to generate X-rays XR. The X-rays XR are emitted to the outside from the X-ray passage hole 53a formed in the frame 36 of the rotating anode unit 3. The X-ray passage hole 53a is hermetically sealed by the window member 7. The rotation axis A is inclined relative to the direction axis (the emission axis of the electron beam EB) of the electron beam EB incident on the target 31. The details of the rotating anode unit 3 will be described later.

[0033] The magnetic lens 4 controls the electron beam EB. The magnetic lens 4 has one or more coils 4a and a frame 4b that accommodates these coils 4a. Each coil 4a is arranged in a manner to surround the path 8 through which the electron beam EB passes. Each coil 4a is an electromagnetic coil that generates a magnetic force acting on the electron beam EB between the electron gun 2 and the target 31 by being energized. One or more coils 4a, for example, include a focusing coil that focuses the electron beam EB on the target 31. One or more coils 4a may also include a deflection coil that deflects the electron beam EB. The focusing coil and the deflection coil may also be arranged along the path 8.

[0034] The exhaust section 5 includes an exhaust pipe 5a and a vacuum pump 5b. The exhaust pipe 5a is provided in the frame 6 and connected to the vacuum pump 5b. The vacuum pump 5b evacuates the internal space S1 defined by the frame 6 via the exhaust pipe 5a. The frame 6 defines the internal space S1 together with the frame 4b of the magnetic lens 4, and maintains the internal space S1 in a vacuumed state. By the vacuuming of the vacuum pump 5b, the passage 8 is vacuumed, and the internal space S2 defined by the frame 36 of the rotating anode unit 3 is also vacuumed. In the case where the frame 6 is hermetically sealed in a state where the internal spaces S1, S2 and the passage 8 are vacuumed, the vacuum pump 5b may not be provided.

[0035] In the X-ray generating device 1, a voltage is applied to the electron gun 2 in a state where the internal spaces S1 and S2 and the passage 8 are evacuated, and an electron beam EB is emitted from the electron gun 2. The electron beam EB is focused by the magnetic lens 4 so as to become a desired focus on the target 31, and is incident on the rotating target 31. When the electron beam EB is incident on the target 31, X-rays XR are generated in the target 31, and the X-rays XR are emitted to the outside from the X-ray passage hole 53a.

[0036] [Rotating anode unit]

[0037] like Figure 2 to Figure 5 As shown, the rotary anode unit 3 includes a target 31 , a target support (rotation support) 32 , a shaft 33 , and a flow path forming member 34 .

[0038] The target 31 is formed into a circular plate shape, constituting a circular electron incident surface 31a. The target support body 32 is formed into a circular flat plate shape. The target 31 has an electron incident surface 31a on which the electron beam EB is incident, a back surface 31b on the opposite side of the electron incident surface 31a, and an inner side surface 31c and an outer side surface 31d connected to the electron incident surface 31a and the back surface 31b. The electron incident surface 31a and the back surface 31b are opposite to each other in a parallel manner. The target support body 32 has a surface (first surface) 32a extending approximately perpendicularly to the rotation axis A, a back surface (second surface) 32b on the opposite side of the surface 32a, and a side surface 32c connected to the surface 32a and the back surface 32b. The surface 32a and the back surface 32b are opposite to each other in a parallel manner. In addition, in this example, the target 31 is composed of a single component, but it can also be composed of multiple components.

[0039] The first metal material constituting the target 31 is a heavy metal such as tungsten, silver, rhodium, molybdenum or an alloy thereof. The second metal material constituting the target support 32 is, for example, copper, a copper alloy, etc. The first metal material and the second metal material are selected so that the thermal conductivity of the second metal material is higher than the thermal conductivity of the first metal material.

[0040] The target support body 32 has an outer portion 41 to which the target 31 is fixed, and an inner portion 42 including a rotation axis A (through which the rotation axis A passes). The inner portion 42 is formed in a circular shape. The outer portion 41 is formed in an annular shape and surrounds the inner portion 42. A first recess 43 is formed on the surface 32a of the outer portion 41. The first recess 43 has an annular recessed structure corresponding to the target 31. The first recess 43 extends in a manner that its outer side is open along the outer edge of the target support body 32 and is exposed on the side surface 32c.

[0041] The surface 32a in the inner portion 42 is a circular continuous flat surface extending approximately perpendicularly to the rotation axis A. The surface 32a extends, for example, perpendicularly to the rotation axis A. "Continuous flat surface" means, for example, that no holes, recesses, or protrusions are formed, and the entire surface is located on one plane. As described later, in the manufacturing process of the rotating anode unit 3, the electron incident surface 31a and the surface 32a are polished at the same time, so the surface 32a may also be a continuous flat surface, especially in the second region R2 (described below) where the second recess 44 is formed as the main body thereof. On the other hand, a balance adjustment hole 42b (described below) may be provided, for example, at the outer edge portion closer to the outside than the second region R2.

[0042] The target 31 is arranged so as to be fitted into the first recess 43. The entire surface of the electron incident surface 31a of the target 31 is located on the same plane as the surface 32a of the target support body 32. In this example, the electron incident surface 31a and the surface 32a are continuous without a gap. In the manufacturing process of the rotating anode unit 3, after the target 31 is arranged in the first recess 43, the electron incident surface 31a and the surface 32a are polished at the same time. As a result, the electron incident surface 31a and the surface 32a are positioned on the same plane. However, due to the difference in hardness between the first metal material constituting the target 31 and the second metal material constituting the target support body 32, there may be a slight height difference between the electron incident surface 31a and the surface 32a. For example, when the thickness of the target 31 is about several mm and the hardness of the first metal material is higher than the hardness of the second metal material, the electron incident surface 31a may protrude relative to the surface 32a by, for example, about tens of μm. The phrase “the electron incident surface 31 a is located on the same plane as the surface 32 a ” includes a case where the electron incident surface 31 a is located on the same plane as the surface 32 a although there is a slight height difference as described above.

[0043] The entire surface of the back surface 31b of the target 31 is in contact with the bottom surface 43a of the first recess 43. The entire surface of the inner side surface 31c of the target 31 is in contact with the side surface 43b of the first recess 43. From the viewpoint of the heat dissipation of the target 31, the entire surface of the back surface 31b of the target 31 and the inner side surface 31c of the target 31 may be in contact with the first recess 43, but it is sufficient as long as at least a portion of the back surface 31b and the inner side surface 31c are in contact with the first recess 43. The outer side surface 31d of the target 31 is located on the same plane as the side surface 32c of the target support body 32. The outer side surface 31d of the target 31 may not be located on the same plane as the side surface 32c of the target support body 32, but may protrude or be recessed from the side surface 32c. If the thickness (maximum thickness) of the target 31 is t, the contact width W between the bottom surface 43a of the first recess 43 and the target 31 is greater than 2t and less than 8t. The flatness and parallelism of the electron incident surface 31 a are 15 μm or less.

[0044] The surface roughness Ra of the entire surface of the electron incident surface 31a of the target 31 is less than 0.5μm. In other words, the electron incident surface 31a is polished to a surface roughness Ra of less than 0.5μm. Therefore, the surface roughness Ra of the surface 32a is also less than 0.5μm. The surface roughness Ra of the back surface 31b of the target 31 (the surface in contact with the bottom surface 43a of the first recess 43) and the bottom surface 43a of the first recess 43 are both less than 0.8μm. The sum of the surface roughness Ra of the back surface 31b and the surface roughness Ra of the bottom surface 43a is less than 1.6μm. In other words, the back surface 31b and the bottom surface 43a are polished to a surface roughness Ra of less than 0.8μm. The surface roughness Ra is the arithmetic mean roughness specified in Japanese Industrial Standards (JIS B 0601).

[0045] A second recess 44 is formed on the back surface 32b of the inner portion 42. The second recess 44 defines a flow path 45 for circulating the refrigerant CL1 together with the shaft 33 and the flow path forming member 34. Figure 2 and Figure 5 As shown in the figure, the second recess 44 has a first portion 44a for arranging the shaft 33 and the flow path forming member 34, and a second portion 44b connected to the first portion 44a and constituting the flow path 45. The first portion 44a is formed in a cylindrical shape, and the second portion 44b is formed in a bottomed recessed shape. The peripheral surface of the second portion 44b is a curved surface that is curved in a manner that the farther away from the shaft 33, the closer to the rotation axis A. When viewed from a direction parallel to the rotation axis A, the second recess 44 is separated from the first recess 43 (target 31) (not overlapped).

[0046] The thickness T1 of the first region R1 where the first recess 43 is formed in the outer portion 41 is thicker than the thickness T2 of the second region R2 where the second recess 44 is formed in the inner portion 42. The thickness T1 is the maximum thickness in the first region R1. The thickness T2 is the minimum thickness in the second region R2. The difference between the thickness T2 of the second region R2 and the thickness t of the target 31 (the depth of the first recess 43) is smaller than the difference between the thickness T1 of the first region R1 and the thickness T2 of the second region R2. In this example, the thickness T2 of the second region R2 is thinner than the thickness t of the target 31 (the depth of the first recess 43).

[0047] In the outer portion 41, a plurality of (16 in this example) insertion holes 41a are formed that penetrate between the bottom surface 43a of the first recess 43 and the back surface 32b of the target support body 32. The plurality of insertion holes 41a are arranged at equal intervals along the circumferential direction of a circle centered on the rotation axis A. In the target 31, a plurality of (16 in this example) fastening holes 31e are formed that penetrate between the electron incident surface 31a and the back surface 31b. The target 31 is detachably fixed to the target support body 32 by fastening a fastening member (not shown) inserted through the insertion hole 41a to the fastening hole 31e. The fastening member may also be, for example, a bolt. When fixing the target 31 to the target support body 32, in addition to the fastening structure, welding or diffusion bonding may also be used.

[0048] A plurality of (six in this example) fastening holes 42a for fixing the shaft 33 are formed on the back surface 32b of the inner portion 42. The plurality of fastening holes 42a are arranged at equal intervals along the edge of the second recess 44 and along the circumferential direction of a circle centered on the rotation axis A. The shaft 33 is detachably fixed to the target support 32 by fastening a fastening member (not shown) inserted through the insertion hole 33a of the shaft 33 to the fastening hole 42a. The fastening member may be, for example, a bolt.

[0049] A plurality of (36 in this example) balance adjustment holes 42b for adjusting the weight balance of the rotating anode unit 3 are formed on the back surface 32b of the inner portion 42. The plurality of balance adjustment holes 42b are arranged at equal intervals along the circumferential direction of a circle centered on the rotation axis A. For example, the weight balance of the rotating anode unit 3 can be adjusted by fixing a weight (not shown) to one or more holes selected from the plurality of balance adjustment holes 42b. The weight can also be fixed to the target support 32, for example, by fastening a fastening member such as a bolt to the balance adjustment hole 42b. Conversely, the weight balance of the rotating anode unit 3 can also be adjusted by enlarging the hole by cutting the balance adjustment hole 42b. As described above, the balance adjustment hole 42b can also be provided at the outer edge portion of the surface 32a that is further outside than the second region R2. The weight balance of the rotating anode unit 3 can also be adjusted by adding a weight to or removing a portion of the balance adjustment hole 42b in the target support 32. In this way, a structure for adjusting the weight balance of the rotary anode unit 3 may be provided in the region that is the outer edge with respect to the rotation axis A, particularly in the region outside the region where the flow path 45 is formed.

[0050] The shaft 33 and the flow path forming member 34 are fixed to the target support body 32 from the back side 32b. A portion of the shaft 33 is arranged on the first portion 44a of the second recess 44. As described above, the shaft 33 is fixed to the target support body 32 by the fastening member fastened to the fastening hole 42a. The flow path forming member 34 has a cylindrical portion 34a and a flange portion 34b protruding from the end of the cylindrical portion 34a to the outside. The cylindrical portion 34a is formed in a cylindrical shape and is arranged inside the shaft 33. The flange portion 34b is formed in a disc shape and is spaced apart from the surface of the second recess 44 and each of the shaft 33. The flow path forming member 34 is fixed to the non-rotating portion of the rotating anode unit 3 not shown in the figure in a manner that does not rotate together with the target support body 32 and the shaft 33.

[0051] The flow path 45 for circulating the coolant CL1 is defined by the second recess 44, the shaft 33 and the flow path forming member 34. The coolant CL1 is a liquid coolant such as water or antifreeze. The flow path 45 includes: a first portion 45a formed between the shaft 33 and the cylindrical portion 34a and the flange portion 34b of the flow path forming member 34; a second portion 45b formed between the target support 32 and the flange portion 34b of the flow path forming member 34; and a third portion 45c formed in the cylindrical portion 34a of the flow path forming member 34. The coolant CL1 is supplied to the first portion 45a, for example, from a coolant supply device (not shown). The coolant supply device may also be a cooler that can supply the coolant CL1 adjusted to a predetermined temperature. The coolant CL1 supplied to the first portion 45a flows through the second portion 45b and is discharged in the third portion 45c.

[0052] The rotary anode unit 3 further includes a drive unit 35 for rotating the target 31, the target support 32, and the shaft 33, and a frame 36 ( Figure 1 The drive unit 35 may include a motor as a drive source. The target 31, the target support 32, and the shaft 33 rotate around the rotation axis A as a whole by rotating the shaft 33 using the drive unit 35.

[0053] As described above, in the rotating anode unit 3, the target support 32 is formed of a second metal material having a higher thermal conductivity than the first metal material constituting the target 31. Thus, the cooling performance can be improved. In addition, the first recess 43 in which the target 31 is arranged is formed on the surface 32a in the outer portion 41 of the target support 32, and the second recess 44 defining the flow path 45 for circulating the coolant CL1 is formed on the back surface 32b in the inner portion 42 of the target support 32. The thickness T1 of the first region R1 in which the first recess 43 is formed in the outer portion 41 is thicker than the thickness T2 of the second region R2 in which the second recess 44 is formed in the inner portion 42. Thus, the heat capacity of the first region R1 can be increased, and the cooling efficiency of the second region R2 can be improved. As a result, the heat generated by the target 31 can be stored in the first region R1, and the heat stored in the first region R1 can be efficiently cooled in the second region R2. Therefore, the cooling performance is improved in the rotating anode unit 3. Furthermore, the electron incident surface 31a of the target 31 is located on the same plane as the surface 32a extending substantially perpendicularly to the rotation axis A of the target support 32. Thus, the workability of the polishing operation of the electron incident surface 31a and the surface 32a is improved.

[0054] As a confirmation experiment, an X-ray generator 1 was manufactured and evaluated. In the case of insufficient cooling performance, it is believed that the target support 32 is in a high temperature state of more than 100°C, which will cause the coolant CL1 to boil. However, during the 1000-hour operation period, the coolant CL1 was not heated to boiling. No changes or damages were caused to the target 31. The light amount of the X-ray XR did not change by more than 3%.

[0055] The difference between the thickness T2 of the second region R2 and the thickness t of the target 31 is smaller than the difference between the thickness T1 of the first region R1 and the thickness T2 of the second region R2. Thus, the cooling efficiency of the second region R2 can be further improved, and the heat generated by the target 31 can be easily transferred to the first region R1 having a large heat capacity.

[0056] The surface roughness Ra of the bottom surface 43a of the first concave portion 43 and the back surface 31b of the target 31 in contact with the bottom surface 43a is 1.6 μm or less. Thus, the target 31 and the target support 32 can be brought into suitable contact with each other, and the cooling efficiency can be further improved. That is, the surface area of ​​the contact surface between the target 31 and the target support 32 can be increased.

[0057] The surface roughness Ra of the electron incident surface 31a of the target 31 is 0.5 μm or less. As a result, a large amount of X-rays can be emitted from the target 31 when an electron beam is incident. That is, self-absorption in which the X-rays emitted from the target 31 are shielded by the surface irregularities of the electron incident surface 31a can be suppressed. In addition, if the surface of the electron incident surface 31a has irregularities, stress concentration occurs at the irregularities, but by reducing the surface roughness of the electron incident surface 31a, such stress concentration can be alleviated.

[0058] The contact width W between the target 31 and the bottom surface 43a of the first recess 43 is greater than or equal to 2t and less than or equal to 8t. When the contact width W is greater than or equal to 2t, the contact area between the target 31 and the target support 32 can be increased, and the cooling efficiency can be further improved. In addition, when the contact width W is less than or equal to 8t, the area of ​​the second region R2 can be ensured, and the cooling efficiency of the second region R2 can be further improved.

[0059] The outer portion 41 is provided with an insertion hole 41a that passes through the bottom surface 43a of the first recess 43 and the back surface 32b of the target support body 32. The target 31 is fixed to the target support body 32 by a fastening member inserted through the insertion hole 41a. Thus, the target 31 and the target support body 32 can be further closely attached and fixed.

[0060] The rotary anode unit 3 includes a shaft 33 fixed to the target support 32 from the back surface 32b side and defining a flow path 45 together with the second recess 44. Thus, the target support 32 can be rotated via the shaft 33, and the flow path 45 can be defined by the second recess 44 and the shaft 33.

[0061] The rotating anode unit 3 includes a flow path forming member 34 having a cylindrical portion 34a disposed in the shaft 33 and a flange portion 34b protruding outward from the cylindrical portion 34a, and defining a flow path 45 together with the second recessed portion 44 and the shaft 33. Thus, the flow path 45 can be defined by the second recessed portion 44, the shaft 33, and the flow path forming member 34.

[0062] [Cooling mechanism of magnetic lens]

[0063] like Figure 6As shown, the frame 36 of the rotating anode unit 3 has a wall portion 51. The wall portion 51 includes a first wall 52 and a second wall 53. The first wall 52 is arranged between the target 31 and the coil 4a of the magnetic lens 4 in a manner opposite to the target 31. The first wall 52 is formed in a plate shape and extends in a manner intersecting the rotation axis A and the X direction (the first direction in which the electron beam EB passes through the electron passage hole 52a). An electron passage hole 52a for the electron beam EB to pass through is formed in the first wall 52. The electron passage hole 52a penetrates the first wall 52 along the X direction (the direction along the tube axis of the X-ray generating device 1, that is, the direction along the emission axis of the electron beam EB) and is connected to the passage 8 of the magnetic lens 4.

[0064] The second wall 53 is formed in a plate shape and extends from the first wall 52 along the X direction. An X-ray passage hole 53a is formed in the second wall 53 for the X-ray XR emitted from the target 31 to pass through. The X-ray passage hole 53a penetrates the second wall 53 along the Z direction (third direction) perpendicular to the X direction. A window member 7 is provided on the outer surface of the second wall 53 in such a way as to airtightly close the X-ray passage hole 53a. The window member 7 is formed in a flat plate shape by, for example, a metal material, so that the X-ray XR passes through. As an example of a metal material constituting the window member 7, beryllium (Be) can be cited.

[0065] like Figure 6 As shown, the first wall 52 has a first surface 52b and a second surface 52c on the opposite side of the first surface 52b. The first surface 52b is opposite to the electron incident surface 31a of the target 31 and the surface 32a of the target support body 32. The first surface 52b extends parallel to the electron incident surface 31a and the surface 32a, and is inclined relative to the X direction and the Z direction.

[0066] The second surface 52c is opposite to the frame 4b of the magnetic lens 4. In this example, the second surface 52c is in contact with the frame 4b. The second surface 52c includes a contact portion 52d. The contact portion 52d is a flat surface extending perpendicularly to the X direction. The outer surface of the frame 4b of the magnetic lens 4 is in contact with the contact portion 52d. The outer surfaces of the frame 4b and the frame 6 are joined to the second surface 52c (contact portion 52d), for example, by welding or diffusion bonding. The frame 36 of the rotating anode unit 3 can also be installed freely relative to the frame 4b and the frame 6. At this time, an airtight sealing member such as an O-ring may be interposed between the second surface 52c (contact portion 52d) and the frame 4b and the frame 6.

[0067] A flow path 61 for circulating the refrigerant CL2 is formed on the first wall 52. A groove 62 is formed on the abutting portion 52d of the second surface 52c of the first wall 52. The flow path 61 is defined by closing the groove 62 using the frame 4b of the magnetic lens 4. The refrigerant CL2 is supplied to the flow path 61, for example, from a refrigerant supply device (not shown). The refrigerant supply device can also be a chiller that can supply the refrigerant CL2 adjusted to a specified temperature. The refrigerant CL2 is a liquid refrigerant such as water or antifreeze.

[0068] Figure 7 2 is a diagram of the second surface 52c of the first wall 52 as viewed from the X direction. Figure 7 The shape of the flow path 61 when viewed from the X direction will be described. Figure 7 In the figure, for easy understanding, the flow path 61 is shaded. The flow path 61 extends in a winding manner between the supply position P1 for supplying the refrigerant CL2 and the discharge position P2 for discharging the refrigerant CL2. The flow path 61 includes a plurality of (four in this example) curved portions 63 extending along the circumferential direction of a circle centered on the electron passage hole 52a. The plurality of curved portions 63 are arranged at approximately equal intervals along the Z direction (the third direction perpendicular to the first direction).

[0069] The flow path 61 includes a plurality of (three in this example) connection portions 64A to 64C that alternately connect a plurality of curved portions 63. The connection portions 64A to 64C extend in a curved manner. The flow path 61 further includes a straight portion 65 that connects the supply position P1 and the curved portion 63, and a straight portion 66 that connects the curved portion 63 and the discharge position P2.

[0070] The bent portion 63A closest to the electron passage hole 52a among the plurality of bent portions 63 is located on both sides of the electron passage hole 52a in the Y direction (the second direction perpendicular to the first direction). In other words, the flow path 61 extends in the Y direction so as to sandwich (surround in a U-shape) the electron passage hole 52a on both sides of the electron passage hole 52a.

[0071] In the flow path 61, the coolant CL2 flows from the supply position P1 to the discharge position P2. In the flow path 61, the upstream side (the side close to the supply position P1) is arranged near the electron passage hole 52a compared with the downstream side (the discharge position P2 side). For example, the curved portion 63A is arranged to be closer to the electron passage hole 52a than the curved portion 63 other than the curved portion 63A. In other words, the flow path 61 includes a first portion (curved portion 63A), and a second portion (curved portion 63 other than the curved portion 63A) connected to the first portion and located on the opposite side of the electron passage hole 52a relative to the first portion, and the X-ray generating device 1 is constructed in a manner that the coolant CL2 flows from the first portion to the second portion. In this way, the coolant is first introduced (a coolant with a lower temperature is introduced) to the area close to the electron passage hole 52a, thereby improving the cooling efficiency of the structure near the electron passage hole 52a. In the vicinity of the electron passage hole 52a, the temperature is easily increased by the influence of the electron beam EB (especially the influence of the reflected electrons from the target 31).

[0072] The center C of the region RG where the flow path 61 is formed in the first wall 52 is located on the opposite side of the X-ray passage hole 53a with respect to the electron passage hole 52a ( Figure 7 That is, the flow path 61 is formed near the opposite side of the X-ray passage hole 53a with respect to the electron passage hole 52a.

[0073] As described above, in the X-ray generating device 1, the rotating anode unit 3 is configured so as to rotate the target 31. Thus, the electron beam EB can be incident on the rotating target 31, and the electron beam EB can be prevented from being locally incident on the target 31. As a result, the incident amount of the electron beam EB can be increased. In addition, in the first wall 52 (wall portion 51) arranged between the target 31 and the coil 4a and opposite to the target 31, in addition to the electron passing hole 52a for the electron beam EB to pass through, a flow path 61 configured so as to allow the coolant CL2 to flow is formed. Thus, by allowing the coolant CL2 to flow through the flow path 61, the wall portion 51 and the magnetic lens 4 can be cooled. Therefore, even when the incident amount of the electron beam EB on the target 31 increases and the reflected electrons from the target 31 increase, the wall portion 51 and the magnetic lens 4 can be suppressed from becoming hot. Therefore, according to the X-ray generating device 1, the occurrence of adverse conditions caused by the heating of the reflected electrons can be suppressed. That is, the occurrence of an undesirable situation caused by the heat generated by the wall portion 51 due to the reflected electrons that are not absorbed by the target 31 and reflected, and the high temperature of the periphery of the coil 4a due to the combination of the heat generated by the coil 4a due to the power on, can be suppressed. As such an undesirable situation, the reduction of the controllability of the electron beam EB caused by the coil 4a, the damage of the surrounding components, etc. can be cited. When the coil 4a is heated to a high temperature, the controllability of the electron beam EB is reduced, which may cause the size or position of the focus of the X-ray XR to change. In addition, there is also the possibility of destroying the vacuum due to the damage of the window component 7 or the frame 36. According to the X-ray generating device 1, the occurrence of such an undesirable situation can be suppressed.

[0074] As a confirmation experiment, an X-ray generator 1 was manufactured and evaluated. As a result, it was confirmed that the temperature rise of the wall portion 51 and the magnetic lens 4 was suppressed. During the 1000-hour operation, the size and position of the focus of the X-ray XR did not change significantly. The window member 7 did not have any abnormality.

[0075] The flow path 61 extends so as to be located on both sides of the electron passage hole 52a in the Y direction when viewed from the X direction. This makes it possible to effectively cool the periphery of the electron passage hole 52a into which a large amount of reflected electrons are incident.

[0076] The flow path 61 includes a plurality of curved portions 63 extending in the circumferential direction of a circle centered on the electron passage hole 52a when viewed from the X direction. This allows the periphery of the electron passage hole 52a to be effectively cooled.

[0077] The flow path 61 includes a plurality of curved portions 63 arranged in the Z direction. This allows the periphery of the electron passage hole 52a to be effectively cooled.

[0078] The flow path 61 includes a first portion (bend portion 63A), and a second portion (bend portion 63 other than the bend portion 63A) connected to the first portion and located on the opposite side of the electron passage hole 52a relative to the first portion, and the X-ray generating device 1 is configured in a manner that the coolant CL2 flows from the first portion to the second portion. In other words, the X-ray generating device 1 includes a coolant supply device configured in a manner that the coolant CL2 flows from the first portion to the second portion. Thus, the flow path 61 includes the first portion and the second portion, so that the path for the coolant CL2 to flow can be lengthened, and the wall portion 51 and the magnetic lens 4 can be effectively cooled. In addition, the coolant CL2 first flows through the first portion close to the electron passage hole 52a, so that the periphery of the electron passage hole 52a can be effectively cooled.

[0079] The wall portion 51 is provided with an X-ray passage hole 53a through which X-rays emitted from the target 31 pass. When viewed from the X direction, the center C of the region RG in which the flow path 61 is formed in the wall portion 51 is located on the opposite side of the X-ray passage hole 53a relative to the electron passage hole 52a. Figure 7 Thus, the degree of freedom in design related to the X-ray passage hole 53a can be increased. For example, if the flow path 61 is to be formed on the X-ray passage hole 53a side relative to the electron passage hole 52a, it is possible that the second wall 53 having the X-ray passage hole 53a formed therein needs to be thickened, but such a situation does not occur in the above embodiment.

[0080] The X-ray passage hole 53a is formed in the second wall 53, and the electron passage hole 52a and the flow path 61 are formed in the first wall 52. Thus, the degree of freedom in designing the X-ray passage hole 53a can be improved.

[0081] A groove 62 is formed on the second surface 52c of the wall portion 51, and the flow path 61 is defined by closing the groove 62 with the frame 4b of the magnetic lens 4. Thus, the magnetic lens 4 can be effectively cooled. In addition, compared with the case where the flow path 61 is formed in the wall portion 51, the manufacturing process can be simplified.

[0082] Wall portion 51 constitutes frame 36 of rotary anode unit 3. Thus, frame 36 of rotary anode unit 3 can be used for cooling.

[0083] [Modifications]

[0084] You can also Figure 8The target 31 and the target support body 32 are configured as in the modified example shown in the figure. In the modified example, the target 31 is formed in an L-shaped cross section. The target 31 has a first part 31f and a second part 31g. The first part 31f includes an electron incident surface 31a, and the second part 31g includes a back surface 31b. The width of the first part 31f is narrower than the width of the second part 31g. A gap is formed between the electron incident surface 31a and the surface 32a of the target support body 32. In the modified example, the electron incident surface 31a is also located on the same plane as the surface 32a. The target 31 is fixed to the target support body 32 by bonding or diffusion bonding the back surface 31b to the bottom surface 43a of the first recess 43 using solder. In such a modified example, as in the above-mentioned embodiment, the cooling performance is also improved, and the workability of the grinding operation of the electron incident surface 31a of the target 31 and the surface 32a of the target support body 32 is improved.

[0085] The present invention is not limited to the above-mentioned embodiments and modifications. For example, the materials and shapes of each component are not limited to the above-mentioned materials and shapes, and various materials and shapes can be used. In the above-mentioned embodiment, the surface roughness Ra of the bottom surface 43a of the first recess 43 and the back surface 31b of the target 31 is 0.8 μm or less, but if the sum of the surface roughness Ra of the two is 1.6 μm or less, there may be a difference in the surface roughness Ra of each other. In the above-mentioned embodiment, the flow path 61 is defined by closing the groove 62 using the frame 4b of the magnetic lens 4, but the flow path 61 may be formed as a hole in the wall portion 51. Alternatively, the wall portion 51 itself may also be provided with a cover-shaped member for closing the groove 62. The flow path 61 may also be formed in the wall portion of the frame 4b constituting the magnetic lens 4 instead of being formed in the wall portion 51 of the frame 36 constituting the rotating anode unit 3.

Claims

1. A rotating anode unit, wherein: have: a target formed of a first metal material and constituting a ring-shaped electron incident surface; and The target support is formed of a second metal material in a flat plate shape and has a first surface extending substantially perpendicularly to the rotation axis and a second surface opposite to the first surface. The thermal conductivity of the second metal material is higher than the thermal conductivity of the first metal material. The target support body has an inner portion including the rotation axis and an outer portion to which the target is fixed. A first recess is formed on the first surface of the outer portion, The target is arranged in the first recess, and the electron incident surface of the target is located on the same plane as the first surface. The second surface of the inner portion is provided with a second recessed portion configured to define a flow path for circulating a refrigerant. The entire thickness of the first region in the outer portion where the first recess is formed is thicker than the minimum thickness of the second region in the inner portion where the second recess is formed, When viewed from a direction parallel to the rotation axis, the second region is separated from the first region.

2. The rotating anode unit according to claim 1, wherein: A difference between a minimum thickness of the second region and a thickness of the target is smaller than a difference between a maximum thickness of the first region and a minimum thickness of the second region.

3. The rotating anode unit according to claim 1, wherein: At least one of the bottom surface of the first recessed portion and a surface of the target in contact with the bottom surface has a surface roughness Ra of 1.6 μm or less.

4. The rotating anode unit according to claim 1, wherein: The electron incident surface of the target has a surface roughness Ra of 0.5 μm or less.

5. The rotating anode unit according to claim 1, wherein: When the thickness of the target is t, the contact width between the target and the bottom surface of the first recessed portion is greater than or equal to 2t and less than or equal to 8t.

6. The rotating anode unit according to claim 1, wherein: The outer portion has an insertion hole formed therein so as to pass through the bottom surface of the first recess and the second surface. The target is fixed to the target support body by a fastening member inserted through the insertion hole.

7. The rotating anode unit according to claim 1, wherein: The target device further includes a shaft that is fixed to the target support body from the second surface side and defines the flow path together with the second recessed portion.

8. The rotating anode unit according to claim 7, wherein: The invention further comprises a flow path forming member having a cylindrical portion arranged in the shaft and a flange portion protruding outward from the cylindrical portion, and defining the flow path together with the second recessed portion and the shaft.

9. An X-ray generating device, wherein: A rotating anode unit according to claim 1 is provided.

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