X-ray generating device

Abstract

The X-ray generating device of the present invention comprises: an electron gun that emits an electron beam; a rotating anode unit that has a target that receives the electron beam and generates X-rays and is configured to rotate the target; a magnetic lens that has a coil that is configured to generate a magnetic force acting on the electron beam between the electron gun and the target; and a wall portion that is arranged between the target and the coil so as to face the target. The wall portion is formed with: an electron passage hole through which the electron beam passes, and a flow path configured so as to flow a coolant.

Description

Technical Field

[0001] One aspect of the present disclosure relates to an X-ray generating device. Background Art

[0002] Japanese Patent Application Laid-Open No. 2009-193789 discloses an X-ray generator that generates X-rays by causing an electron beam emitted from a cathode to be incident on a target. In this X-ray generator, the position of the target is fixed.

[0003] Prior art literature

[0004] Patent Literature

[0005] Patent Document 1: Japanese Patent Application Publication No. 2009-193789 Summary of the invention

[0006] Problems to be solved by the invention

[0007] In the above-mentioned X-ray generating device, since the electron beam is continuously incident on a part of the target, the part is easily damaged, and the incident amount of the electron beam is limited. Therefore, it is considered to rotate the target and allow the electron beam to be incident on the rotating target. In this case, it is possible to avoid the electron beam from being incident on the target locally, and the incident amount of the electron beam can be increased.

[0008] However, if the incident amount of the electron beam increases, the reflected electrons that are not absorbed by the target and reflected also increase. Therefore, by incident reflected electrons on the wall portion arranged in a manner facing the target, there is a possibility that the wall portion is heated to a high temperature. In particular, when a coil for controlling the electron beam is arranged near the wall portion, since the coil itself is also heated by being energized, the heat of the coil and the heat of the wall portion are combined with each other, and there is a possibility that the temperature around the coil is heated to a high temperature. In this case, defects such as reduced controllability of the electron beam or damage to surrounding components may occur due to the coil.

[0009] An object of one aspect of the present disclosure is to provide an X-ray generating device that can suppress the occurrence of defects caused by heat generated by reflected electrons.

[0010] Methods used to solve problems

[0011] An X-ray generating device according to one aspect of the present invention comprises: an electron gun that emits an electron beam; a rotating anode unit that has a target that receives the electron beam and generates X-rays and is configured to rotate the target; a magnetic lens that has a coil that is configured to generate a magnetic force acting on the electron beam between the electron gun and the target; and a wall portion that is arranged between the target and the coil so as to face the target, and the wall portion has: an electron passage hole through which the electron beam passes, and a flow path configured to allow a coolant to flow.

[0012] In the X-ray generating device, the rotating anode unit is configured to rotate the target. Thus, the electron beam can be incident on the rotating target, and the electron beam can be prevented from being locally incident on the target. As a result, the incident amount of the electron beam can be increased. In addition, in the wall portion arranged between the target and the coil and facing the target, in addition to the electron passage hole through which the electron beam passes, a flow path configured in a manner of flowing a coolant is also formed. Thus, by allowing the coolant to flow in the flow path, the wall portion and the magnetic lens can be cooled. Therefore, even when the incident amount of the electron beam on the target increases and the reflected electrons from the target increase, the temperature of the wall portion and the magnetic lens can still be suppressed. Therefore, according to the X-ray generating device, the generation of defects caused by the heat caused by the reflected electrons can be suppressed.

[0013] When viewed from a first direction in which the electron beam passes through the electron passage hole, the flow path may extend to be located on both sides of the electron passage hole in a second direction perpendicular to the first direction. In this case, the periphery of the electron passage hole into which a large amount of reflected electrons are incident can be effectively cooled.

[0014] When viewed from the first direction in which the electron beam passes through the electron passage hole, the flow path may include at least one curved portion extending in the circumferential direction of a circle centered on the electron passage hole. In this case, the periphery of the electron passage hole can be effectively cooled.

[0015] At least one bent portion may include a plurality of bent portions, and the plurality of bent portions may be arranged in a third direction perpendicular to the first direction. In this case, the periphery of the electron passage hole can be effectively cooled.

[0016] Alternatively, the flow path includes: a first portion, and a second portion connected to the first portion and located on the opposite side of the electron passage hole relative to the first portion, and the X-ray generating device is configured so that the coolant flows from the first portion to the second portion. In this case, since the flow path includes the first portion and the second portion, the path of the coolant flow can be extended, and the wall portion and the magnetic lens can be effectively cooled. In addition, since the coolant first flows to the first portion close to the electron passage hole, the periphery of the electron passage hole can be effectively cooled.

[0017] Alternatively, an X-ray passage hole through which X-rays emitted from the target pass may be formed in the wall portion, and when viewed from a first direction in which the electron beam passes through the electron passage hole, the center of the region in which the flow path is formed in the wall portion is located on the opposite side of the X-ray passage hole relative to the electron passage hole. In this case, the degree of freedom in designing the X-ray passage hole can be increased.

[0018] Alternatively, the wall portion includes: a first wall disposed between the target and the coil in a manner facing the target; and a second wall extending from the first wall along a first direction in which the electron beam passes through the electron passage hole, wherein an X-ray passage hole through which X-rays emitted from the target pass is formed in the second wall, and the electron passage hole and the flow path are formed in the first wall. In this case, the degree of freedom in designing the X-ray passage hole can be increased.

[0019] Alternatively, a groove may be formed on the surface of the wall portion, and the flow path may be defined by closing the groove with the frame of the magnetic lens. In this case, the magnetic lens can be effectively cooled. In addition, the manufacturing process can be simplified compared to the case where the flow path is formed in the wall portion.

[0020] The wall portion may constitute a frame of the rotating anode unit. In this case, the frame of the rotating anode unit can be used for cooling.

[0021] Effects of the Invention

[0022] According to one aspect of the present disclosure, an X-ray generating device can be provided that can suppress the generation of defects caused by heat generated by reflected electrons. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 It is a structural diagram of an X-ray generating device according to an embodiment.

[0024] Figure 2 is a cross-sectional view of a portion of a rotating anode unit.

[0025] Figure 3 It is a front view of the target and the target support.

[0026] Figure 4 It is a bottom view of the target support.

[0027] Figure 5 is along Figure 4 Cross-sectional view of line VV.

[0028] Figure 6 yes Figure 1 A magnified portion of the image.

[0029] Figure 7 It is a front view of the frame of the rotating anode unit.

[0030] Figure 8 It is a cross-sectional view of a target and a target support body according to a modified example. DETAILED DESCRIPTION

[0031] Hereinafter, one embodiment of the present disclosure will be described in detail with reference to the accompanying drawings. In the following description, the same or corresponding elements are denoted by the same reference numerals, and repeated descriptions are omitted.

[0032] [X-ray generating device]

[0033] like Figure 1 As 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 airtightly closed 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.

[0034] The magnetic lens 4 controls the electron beam EB. The magnetic lens 4 includes 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 passage 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. For example, the one or more coils 4a include: a focusing coil that focuses the electron beam EB on the target 31. The 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 passage 8.

[0035] 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 and the frame 4b of the magnetic lens 4 define the internal space S1 and maintain the internal space S1 in a vacuumed state. By the vacuuming by the vacuum pump 5b, the passage 8 is evacuated, and the internal space S2 defined by the frame 36 of the rotating anode unit 3 is also evacuated. In the case where the frame 6 is hermetically sealed in a state where the internal spaces S1, S2 and the passage 8 are evacuated, the vacuum pump 5b may not be provided.

[0036] 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.

[0037] [Rotating anode unit]

[0038] like Figure 2 to Figure 5As shown, the rotary anode unit 3 includes a target 31 , a target support (rotation support) 32 , a shaft 33 , and a flow channel forming member 34 .

[0039] 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.

[0040] The first metal material constituting the target 31 is, for example, 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.

[0041] The target support body 32 includes 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 a 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.

[0042] The surface 32a of the inner portion 42 is a circular continuous flat surface extending substantially 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 hole, recess, or protrusion is formed, and the entire surface is located on one plane. As described later, in the manufacturing process of the rotating anode unit 3, since the electron incident surface 31a and the surface 32a are polished at the same time, the surface 32a, in particular, in the second region R2 (described later) forming the main body thereof and having the second recess 44 formed therein, can be a continuous flat surface. On the other hand, for example, a balance adjustment hole 42b (described later) can also be provided in the outer edge portion further outside than the second region R2.

[0043] 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. Thus, 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, tens of μm. “The electron incident surface 31 a and the surface 32 a are located on the same plane” means that even if there is such a slight height difference, the electron incident surface 31 a and the surface 32 a are located on the same plane substantially.

[0044] The entire back surface 31b of the target 31 is in contact with the bottom surface 43a of the first recess 43. The entire inner surface 31c of the target 31 is in contact with the side surface 43b of the first recess 43. From the viewpoint of heat dissipation of the target 31, the entire back surface 31b of the target 31 and the entire inner 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 surface 31c are in contact with the first recess 43. The outer surface 31d of the target 31 and the side surface 32c of the target support 32 are located on the same plane. The outer surface 31d of the target 31 may not be located on the same plane as the side surface 32c of the target support 32, but may protrude or be recessed from the side surface 32c. When 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 may be greater than 2t and less than 8t. The flatness and parallelism of the electron incident surface 31 a are 15 μm or less.

[0045] 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 in a manner that the surface roughness Ra is 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 side 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 side 31b and the surface roughness Ra of the bottom surface 43a is less than 1.6μm. In other words, the back side 31b and the bottom surface 43a are polished in a manner that the surface roughness Ra is less than 0.8μm. The surface roughness Ra is the arithmetic mean roughness defined by Japanese Industrial Standards (JIS B 0601).

[0046] 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 the coolant CL1 to flow 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 on which the shaft 33 and the flow path forming member 34 are arranged, 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) (does not overlap).

[0047] 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. The thickness T1 is the maximum thickness of the first region R1. The thickness T2 is the minimum thickness of 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).

[0048] The outer portion 41 is provided with a plurality of (16 in this example) insertion holes 41a that pass through 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. The target 31 is provided with a plurality of (16 in this example) fastening holes 31e that pass through between the electron incident surface 31a and the back surface 31b. The target 31 is fastened to the fastening hole 31e by a fastening member (not shown) inserted through the insertion hole 41a, and is detachably fixed to the target support body 32. The fastening member may be, for example, a bolt. For fixing the target 31 to the target support body 32, welding or diffusion bonding may be used in addition to the fastening structure.

[0049] 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 fastened to the fastening hole 42a by a fastening member (not shown) inserted through the insertion hole 33a of the shaft 33, and is detachably fixed to the target support body 32. The fastening member may be, for example, a bolt.

[0050] 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 by, for example, 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 on 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 a portion other than the balance adjustment hole 42b of the target support 32 or removing a portion. In this manner, a structure for adjusting the weight balance of the rotary anode unit 3 may be provided in a region that is an outer edge with respect to the rotation axis A, particularly in a region outside the region where the flow path 45 is formed.

[0051] 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 in 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 includes 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 disk shape and faces the surface of the second recess 44 and each of the shaft 33 with a gap. The flow path forming member 34 is fixed to the non-rotating portion of the rotating anode unit 3 (not shown) in a manner that does not rotate together with the target support body 32 and the shaft 33.

[0052] The second recess 44, the shaft 33 and the flow path forming member 34 define a flow path 45 for flowing the coolant CL1. The coolant CL1 is, for example, 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 in the second portion 45b and is discharged in the third portion 45c.

[0053] The rotating anode unit 3 further comprises: a driving 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 when the drive unit 35 rotates the shaft 33.

[0054] 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 of the outer portion 41 of the target support 32, and the second recess 44 defining the flow path 45 for flowing the coolant CL1 is formed on the back surface 32b of 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 in 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, in the rotating anode unit 3, the cooling performance is improved. Furthermore, the electron incident surface 31a of the target 31 and the surface 32a extending substantially perpendicularly to the rotation axis A of the target support 32 are located on the same plane. This improves the workability of polishing the electron incident surface 31a and the surface 32a.

[0055] As a confirmation experiment, an X-ray generator 1 was manufactured and evaluated. When the cooling performance is insufficient, it is considered that the target support 32 is in a high temperature state of more than 100°C and the coolant CL1 boils, but during the operation period of 1000 hours, the coolant CL1 was not heated to boiling. No deformation or damage occurred to the target 31. The light amount of the X-ray XR did not change by more than 3%.

[0056] 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 in the target 31 can be easily transferred to the first region R1 having a larger heat capacity.

[0057] The surface roughness Ra of the bottom surface 43a of the first recess 43 and the back surface 31b of the target 31 in contact with the bottom surface 43a are both 1.6 μm or less. Thus, the target 31 and the target support 32 can be properly contacted, 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.

[0058] 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 the electron beam is incident. That is, the self-absorption of the X-rays emitted from the target 31 by the surface irregularities of the electron incident surface 31a can be suppressed. In addition, if there are irregularities on the surface of the electron incident surface 31a, stress concentration occurs at the irregularities, and by reducing the surface roughness of the electron incident surface 31a, such stress concentration can be alleviated.

[0059] 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. Since 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, since 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.

[0060] The outer portion 41 is provided with an insertion hole 41a extending between the bottom surface 43a of the first recess 43 and the back surface 32b of the target support 32. The target 31 is fixed to the target support 32 by a fastening member inserted through the insertion hole 41a. Thus, the target 31 and the target support 32 can be fixed in closer contact.

[0061] 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.

[0062] The rotating anode unit 3 includes a flow path forming member 34, which includes a cylindrical portion 34a disposed in the shaft 33 and a flange portion 34b protruding outward from the cylindrical portion 34a, and defines 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.

[0063] [Cooling mechanism of magnetic lens]

[0064] 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 facing 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 through which the electron beam EB passes 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, the direction along the emission axis of the electron beam EB), and is connected to the passage 8 of the magnetic lens 4.

[0065] 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 through which the X-ray XR emitted from the target 31 passes is formed in the second wall 53. 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 manner 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 to allow the X-ray XR to pass through. As an example of a metal material constituting the window member 7, beryllium (Be) can be cited.

[0066] 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 faces the electron incident surface 31a of the target 31 and the surface 32a of the target support 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.

[0067] The second surface 52c faces 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 freely installed and disassembled relative to the frame 4b and the frame 6. In this case, an airtight sealing member such as an O-ring may also be interposed between the second surface 52c (contact portion 52d) and the frame 4b and the frame 6.

[0068] A flow path 61 for flowing 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 with 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 may also be a cooler that can supply the refrigerant CL2 adjusted to a specified temperature. The refrigerant CL2 is, for example, a liquid refrigerant such as water or antifreeze.

[0069] Figure 7 This is a diagram of the second surface 52c of the first wall 52 as viewed from the X direction. Figure 7 , which illustrates the shape of the flow path 61 when viewed from the X direction. Figure 7 For ease of 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).

[0070] 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.

[0071] 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 (a second direction perpendicular to the first direction). In other words, the flow path 61 extends on both sides of the electron passage hole 52a in the Y direction so as to sandwich (surround in a U shape) the electron passage hole 52a.

[0072] 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 (close to the supply position P1 side) is arranged closer to the electron passage hole 52a than the downstream side (discharge position P2 side). For example, the curved portion 63A is arranged 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 configured in a manner that the coolant CL2 flows from the first portion to the second portion. In this way, since the coolant is first introduced (the coolant with a lower temperature is introduced) to the area close to the electron passage hole 52a, the cooling efficiency of the structure near the electron passage hole 52a can be improved. In the vicinity of the electron passage hole 52a, the temperature is likely to rise due to the influence of the electron beam EB (particularly, the influence of the reflected electrons from the target 31).

[0073] 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.

[0074] 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) disposed between the target 31 and the coil 4a and facing the target 31, in addition to the electron passage hole 52a through which the electron beam EB passes, a flow path 61 configured so as to flow the coolant CL2 is formed. Thus, by causing the coolant CL2 to flow in 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 to the target 31 increases and the reflected electrons from the target 31 increase, the temperature of the wall portion 51 and the magnetic lens 4 can be suppressed. Therefore, according to the X-ray generating device 1, the generation of defects caused by the heat generated by the reflected electrons can be suppressed. That is, the occurrence of defects caused by the heat generated by the wall 51 due to the reflected electrons that are not absorbed by the target 31 and reflected, and the heat generated by the coil 4a due to the energization, which is combined with each other and causes the temperature around the coil 4a to rise. As such defects, the reduction in the controllability of the electron beam EB caused by the coil 4a, the damage of the surrounding components, etc. can be listed. Since the controllability of the electron beam EB is reduced when the coil 4a is heated to a high temperature, the size or position of the focus of the X-ray XR may change. Alternatively, the vacuum may be destroyed 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 defects can be suppressed.

[0075] As a confirmation experiment, an X-ray generator 1 was manufactured and evaluated. As a result, it was confirmed that the temperature 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.

[0076] When viewed from the X direction, the flow path 61 extends so as to be located on both sides of the electron passage hole 52a in the Y 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.

[0077] When viewed from the X direction, 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. This allows the periphery of the electron passage hole 52a to be effectively cooled.

[0078] 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.

[0079] 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 such a manner that the coolant CL2 flows from the first portion to the second portion. In other words, the X-ray generating device 1 is provided with a coolant supply device configured in such a manner that the coolant CL2 flows from the first portion to the second portion. Thus, since the flow path 61 includes the first portion and the second portion, the path for the coolant CL2 to flow can be extended, and the wall portion 51 and the magnetic lens 4 can be effectively cooled. In addition, since the coolant CL2 first flows to the first portion close to the electron passage hole 52a, the periphery of the electron passage hole 52a can be effectively cooled.

[0080] 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 on 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 designing 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, the second wall 53 on which the X-ray passage hole 53a is formed may need to be thickened. However, in the above-mentioned embodiment, such a situation does not occur.

[0081] 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.

[0082] 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.

[0083] Wall portion 51 constitutes frame 36 of rotary anode unit 3. Thus, frame 36 of rotary anode unit 3 can be used for cooling.

[0084] [Example of variation]

[0085] You can also Figure 8The target 31 and the target support 32 are configured as in the variation shown in the figure. In the variation, the target 31 is formed in an L-shaped cross section. The target 31 includes: 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 32. In the variation, 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 32 by soldering or diffusion bonding the back surface 31b and the bottom surface 43a of the first recess 43. In this variation, as in the above-mentioned embodiment, the cooling performance can be 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 32 can be improved.

[0086] The present disclosure is not limited to the above-mentioned embodiments and variations. For example, the materials and shapes of each structure 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 less than 0.8μm, but if the sum of the surface roughness Ra of the two is less than 1.6μm, 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 by the frame 4b of the magnetic lens 4, but the flow path 61 can also be formed as a hole in the wall portion 51. Alternatively, the wall portion 51 itself can also be provided with a cover-shaped member for closing the groove 62. The flow path 61 can also be formed in the wall portion of the frame 4b constituting the magnetic lens 4, instead of the wall portion 51 of the frame 36 constituting the rotating anode unit 3.

Claims

1. An X-ray generating device comprising: an electron gun which emits an electron beam; a rotating anode unit having a target for generating X-rays by receiving the electron beam and configured to rotate the target; a magnetic lens having a coil configured to generate a magnetic force acting on the electron beam between the electron gun and the target; and a wall portion, which is arranged between the target and the coil and faces the target, The wall portion is provided with: an electron passage hole through which the electron beam passes, and a flow path through which a coolant flows. A groove is formed on the surface of the wall portion, The flow path is defined by closing the groove with the frame of the magnetic lens.

2. The X-ray generating device according to claim 1, wherein: When viewed from a first direction in which the electron beam passes through the electron passage hole, the flow path extends so as to be located on both sides of the electron passage hole in a second direction perpendicular to the first direction.

3. The X-ray generating device according to claim 1, wherein: When viewed from a first direction in which the electron beam passes through the electron passage hole, the flow path includes at least one curved portion extending in a circumferential direction of a circle centered on the electron passage hole.

4. The X-ray generating device according to claim 3, wherein: The at least one curved portion includes a plurality of curved portions, The plurality of bent portions are arranged along a third direction perpendicular to the first direction.

5. The X-ray generating device according to claim 1, wherein: The flow path includes: a first portion, and a second portion connected to the first portion and located on the opposite side of the electron passage hole relative to the first portion. The X-ray generating device is configured such that the cooling medium flows from the first portion to the second portion.

6. The X-ray generating device according to claim 1, wherein: The wall portion is provided with an X-ray passage hole through which the X-rays emitted from the target pass. When viewed from a first direction in which the electron beam passes through the electron passage hole, a center of a region in which the flow path is formed on the wall portion is located on the opposite side of the X-ray passage hole with respect to the electron passage hole.

7. The X-ray generating device according to claim 1, wherein: The wall portion includes: a first wall disposed between the target and the coil so as to face the target; and a second wall extending from the first wall along a first direction in which the electron beam passes through the electron passage hole. The second wall is provided with an X-ray passage hole through which the X-rays emitted from the target pass. The electron passage hole and the flow path are formed in the first wall.

8. The X-ray generating device according to claim 1, wherein: The wall portion constitutes a frame of the rotating anode unit.

9. The X-ray generating device according to claim 1, wherein: The thickness of the wall portion forming the flow path increases as it approaches the electron passage hole.

10. The X-ray generating device according to claim 1, wherein: It also includes: a frame for accommodating the magnetic lens, The refrigerant is in direct contact with both the wall portion and the frame.

11. The X-ray generating device according to claim 1, wherein: The wall portion is formed with an X-ray passage hole through which the X-rays emitted from the target pass. When observed from the first direction where the electron beam passes through the electron passage hole, in the region of the wall where the flow path is formed, the area closer to the X-ray passage hole than the electron passage hole is smaller than the area on the opposite side of the X-ray passage hole than the electron passage hole.

12. The X-ray generating device according to claim 3, wherein: The at least one curved portion includes a plurality of curved portions, The plurality of bent portions are arranged at substantially equal intervals along a third direction perpendicular to the first direction.

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