Neutron convergence device and method for manufacturing the same

Abstract

To provide a neutron convergence device that can be produced in a short time and a manufacturing method.SOLUTION: There is provided a neutron convergence device in which a plurality of units are connected in an axial direction and which includes a neutron supermirror having a predetermined rotational curved surface shape. Each of the plurality of units includes: a plurality of mirror segments having mirror parts constituting a portion of the neutron supermirror with the predetermined curved surface shape; a vacuum chamber; and a coupling flange to which the plurality of mirror segments and the vacuum chamber are attached. Each of the plurality of mirror segments has a flange part at one end, and the vacuum chamber has a first flange part at one end and a second flange part at the other end.SELECTED DRAWING: Figure 4

Description

Technical Field

[0001] The present invention relates to a neutron focusing device and a method for manufacturing the same.

Background Art

[0002] A neutron focusing device is a device that reflects and converges a low-energy neutron beam used for material structure analysis, and dramatically improves the efficiency of neutron scattering experiments. The neutron focusing device is realized by forming a metal multilayer film called a neutron supermirror on a precision machined curved substrate. The inventors of the present invention have developed a technique for realizing neutron focusing devices of various shapes by using a substrate obtained by nickel-phosphorus plating a metal that is easy to process (Non-Patent Documents 1-4).

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Non-Patent Documents

[0004]

Non-Patent Document 1

Non-Patent Document 2

Non-Patent Document 3

[0005] In order to manufacture a neutron supermirror having a rotationally symmetric shape such as an ellipsoidal surface or a paraboloidal surface, it is necessary to machine the inner surface of the rotationally symmetric shape into a precise curved surface and deposit a metal multilayer film. In the prior art, the rotationally symmetric shape is divided into a plurality of segments in the circumferential direction and the axial direction, and the inner surface of each segment is machined into a precise curved surface one by one or in a plurality in the axial direction, a film forming process is performed on the inner surface, and then assembled and integrated.

[0006] Thus, the method of the prior art takes a great deal of time to manufacture a neutron focusing device. Therefore, the present invention proposes a neutron focusing device and a manufacturing method that can be manufactured in a large quantity in a shorter time than the prior art. [Means for Solving the Problems]

[0007] The first aspect of the present invention is a neutron focusing device including a neutron supermirror having a predetermined rotationally curved surface shape, configured by connecting a plurality of units in the axial direction, each of the plurality of units is A plurality of mirror segments divided in the circumferential direction, each mirror segment including a mirror portion that forms part of the neutron supermirror having the predetermined curved surface shape, a vacuum chamber that houses the plurality of mirror segments, and a coupling flange to which the plurality of mirror segments and the vacuum chamber are attached. It is characterized by including: Each of the plurality of mirror segments is provided with a flange portion at one end. A first flange portion is provided at one end of the vacuum chamber, and a second flange portion is provided at the other end. The coupling flange is provided with a first attachment portion for attaching the flange portions of the plurality of mirror segments of the same unit as the coupling flange, and a second attachment portion for attaching the first flange portion of the vacuum chamber of the same unit as the coupling flange, which is located on the outer periphery of the first attachment portion. A neutron focusing device, characterized by the above.

[0008] In this aspect, the coupling flange may be provided with a third attachment portion for attaching the second flange portion of the vacuum chamber of a unit different from the coupling flange.

[0009] In this aspect, the outer surfaces of the flange portions of the plurality of mirror segments, the outer surfaces of the first flange portion and the second flange portion of the vacuum chamber, and both surfaces of the coupling flange may be precision machined to be flat.

[0010] In this aspect, a rotating surface composed of an ellipsoidal surface of revolution, a paraboloidal surface of revolution, a hyperboloidal surface of revolution, or a combination thereof may be formed by the plurality of mirror segments of the plurality of units.

[0011] In this aspect, each of the plurality of mirror segments may have a metal multilayer film formed on an amorphous plating applied to a metal member.

[0012] According to this aspect, with the surface of the flange portion of the mirror segment as a reference surface, it becomes possible to perform batch processing (cutting and polishing) in a state where a plurality of mirror segments are assembled, and it becomes possible to shorten the manufacturing time.

[0013] A second aspect of the present invention is a method for manufacturing a neutron focusing device including a neutron supermirror having a predetermined rotational curved surface shape, in which a plurality of units are connected in the axial direction, each of the plurality of units, a plurality of mirror segments divided in the circumferential direction, each including a mirror portion that forms a part of the neutron supermirror having the predetermined curved surface shape, a vacuum chamber that houses the plurality of mirror segments, a coupling flange that couples the plurality of mirror segments and the vacuum chamber, and comprising, the manufacturing method includes, a processing step of processing the surface of the metal member constituting the mirror segment so as to form a part of the predetermined curved surface shape in a state where a plurality of mirror segments for one unit are assembled, a film forming step of forming a multilayer film supermirror on the surface of the mirror segment in a state where the plurality of mirror segments are placed on a plane, an assembly step of attaching a plurality of mirror segments for one unit and the vacuum chamber to the coupling flange and coupling the plurality of units, and is a method for manufacturing a neutron focusing device including these steps.

[0014] In this aspect, each of the plurality of mirror segments is provided with a flange portion at one end and, the processing step includes, a cutting step of cutting the surface of the mirror segment in a state where the inner surface of the flange portion of the plurality of mirror segments for one unit is attached to a first jig, A polishing step of polishing the surface of the mirror segments in a state where the outer surface of the flange portion of the plurality of mirror segments for one unit is attached to the coupling flange or the second jig. It may be included.

[0015] In this aspect, in the cutting step, the outer surface of the flange portion may be precision machined to a flat surface.

[0016] In this aspect, the assembling step may include a step of attaching the plurality of mirror segments and the vacuum chamber to one surface of the coupling flange.

[0017] In this aspect, the assembling step may include a step of attaching the vacuum chamber of the first unit to the other surface of the coupling flange of the second unit.

[0018] According to this aspect, with the surface of the flange portion of the mirror segment as a reference surface, it is possible to perform batch processing (cutting and polishing) in a state where a plurality of mirror segments are assembled, and it is possible to shorten the manufacturing time.

Effect of the Invention

[0019] According to the present invention, a neutron focusing device can be manufactured in a large quantity in a shorter time than before.

Brief Description of the Drawings

[0020]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Embodiments for Carrying Out the Invention

[0021] Hereinafter, embodiments for carrying out the present invention will be described with reference to the drawings, but the present invention is not limited thereto. The components of each embodiment described below can be combined as appropriate.

[0022] [Configuration of Neutron Focusing Device] With reference to FIGS. 1 to 3, the configuration of the neutron focusing device 1 according to the present embodiment will be described. FIG. 1 is a perspective view of the neutron focusing device 1 composed of three units. FIG. 2 is an exploded view of the neutron focusing device 1 shown in FIG. 1. FIG. 3(A) is a perspective view of one unit constituting the neutron focusing device 1, and FIG. 3(B) is an exploded view of the unit.

[0023] The neutron focusing device 1 will be described as having a neutron supermirror with a rotational ellipsoidal surface shape, but the shape of the mirror is not limited to a rotational ellipsoidal surface and may be any rotational surface. A rotational surface is a surface obtained by rotating a curve in space about a straight line in the space, and typical examples are a rotational ellipsoidal surface, a rotational paraboloid, and a rotational hyperboloid obtained by rotating an ellipse, a parabola, and a hyperbola, respectively. The rotational surface may be a surface combining a rotational ellipsoidal surface, a rotational paraboloid, and a rotational hyperboloid. As an example, a combination of a rotational hyperboloid and a rotational ellipsoidal surface, a combination of a rotational hyperboloid and a rotational paraboloid and the like can be mentioned. However, the mirror shape is not limited to such typical rotational surfaces and may be a rotational surface obtained by rotating any curve. Further, the neutron focusing device 1 has a structure in which a plurality of rotational ellipsoidal mirror units 10 (hereinafter, also simply referred to as unit 10) divided in the axial direction are connected in the axial direction. Here, an example in which three units 10 are connected will be described, but the number of units 10 is not particularly limited.

[0024] As shown in FIGS. 1 and 2, the neutron focusing device 1 shown in this embodiment is composed of three units 10 connected together. Each unit 10 includes a vacuum chamber 11 and a mirror unit 12 composed of a plurality of mirror segments 121 housed inside the vacuum chamber 11. The plurality of mirror segments 121 and the vacuum chamber 11 are respectively coupled to a coupling flange 13 and integrated as a unit. Each unit 10 has a substantially identical configuration except that the shape of the mirror surface of the internal mirror unit 12 is different.

[0025] The units 10 can be connected to each other. Specifically, two units 10 are coupled by coupling the vacuum chamber 11 of one unit to the coupling flange 13 of the other unit.

[0026] In addition, a lid 20 is attached to the end unit 10 to enable the inside of the neutron focusing device 1 to be evacuated. Note that the drawing omits the description of the port for connecting the vacuum pump. The lid 20 is composed of a thin aluminum plate in the central portion, and the central portion serves as a window that transmits neutrons.

[0027] Referring to FIGS. 3(A) and 3(B), the configuration of the unit 10 will be described in more detail. As described above, the unit 10 is generally composed of a vacuum chamber 11, a mirror unit 12, and a coupling precision flange 13.

[0028] The vacuum chamber 11 has a cylindrical portion 111 and first and second flange portions 112 and 113 provided at both ends of the cylindrical portion 111. The cylindrical portion 111 has, for example, an inner diameter of 120 mm and a length of 100 mm, but is not limited to this size. The first flange portion 112 is used to couple with the coupling flange 13 within the same unit 10, and the second flange portion 113 is used to couple with the coupling flange 13 within an adjacent unit 10. For improving the assembly accuracy, the outer surfaces of the first flange portion 112 and the second flange portion 113 are precision machined to be flat. The first flange portion 112 is provided with a fastening portion 114 for coupling with the coupling flange 13 and a positioning member 115 for positioning with the coupling flange 13. The fastening portion 114 is, for example, a screw hole and a screw, and the positioning member 115 is a positioning hole or a positioning pin. The second flange portion 113 is also provided with a fastening portion 114 and a positioning member 115 in the same manner as the first flange portion 112. In this embodiment, both the first flange portion 112 and the second flange portion 113 are provided with 12 screw holes, but only every other 6 screw holes are used for coupling with the coupling flange 13. Also, both the first flange portion 112 and the second flange portion 113 are provided with 4 positioning holes, but only every other 2 positioning holes are used for positioning with the coupling flange 13.

[0029] The mirror unit 12 is composed of a plurality of mirror segments 121, has a cylindrical shape with a flange provided at one end, and the inner surface is a neutron supermirror with a rotational ellipsoidal surface. In this embodiment, the mirror unit 12 is composed of 12 mirror segments 121 divided in the circumferential direction. However, the number of divisions is not limited to this, and it may be more or less.

[0030] The mirror segment 121 is, for example, an aluminum alloy (for example, magnesium added to aluminum) Amorphous plating of nickel-phosphorus (Ni-P) is applied to the attached A5052), and on top of that, it has a multilayer film in which nickel and titanium are alternately laminated. The layer thickness of the multilayer film is provided to increase as it moves away from the substrate, thereby increasing the critical angle of total reflection. This multilayer film corresponds to the mirror section that reflects and converges neutrons.

[0031] At one end of the mirror segment 121, a flange portion 122 is provided. The flange portion 122 is provided with a positioning portion 123 for positioning with the coupling flange 13 and a fastening portion 124 for coupling with the coupling flange 13. In this embodiment, the positioning portion 123 is precision holes for inserting two positioning pins 132, but the positioning portion 123 may be a positioning pin, or more than two precision holes or positioning pins may be provided. The fastening portion 124 is, for example, a screw hole and a screw, and two are provided in this embodiment. Here, the outer surface of the flange portion 122 is a reference surface for attachment to the coupling flange 13 and is precision machined to a flat surface. The inner surface of the flange portion 122 is also precision machined because it becomes a reference surface for attachment to the jig during cutting. The precision of the flat surface precision machining is, for example, on the order of millimeters or sub-millimeters.

[0032] The coupling flange 13 has, on one surface, a first region 131 for attaching a plurality of mirror segments 121 and a second region 134 for attaching the vacuum chamber 11. The first region 131 is the inner region (central region) of the coupling flange 13, and the second region 134 is the outer region (outer peripheral region) of the coupling flange 13. The first region 131 includes positioning pins 132 for positioning the mirror segments 121 and screw holes 133 for fastening the mirror segments 121. A plurality of screw holes 133 are provided concentrically within the first region 131. Two positioning pins 132 and two screw holes 133 are provided for each one mirror segment, and these are provided at 12 locations corresponding to a total of 12 mirror segments. The second region 134 is provided with positioning pins 135 and screw holes 136 for positioning the vacuum chamber 11. A plurality of screw holes 136 are provided concentrically outside the circle in which the plurality of screw holes 133 are formed. The screw holes 136 are also used for attaching the vacuum chamber 11 of another unit. Also, an annular groove is provided between the first region 131 and the second region 134, and an O-ring 14 is disposed therein. In the present disclosure, the first region 131 corresponds to the first attachment portion, the second region 134 corresponds to the second attachment portion, and the region corresponding to the second region 134 among the surfaces opposite to the surface on which the first region and the second region are formed corresponds to the third attachment portion.

[0033] Here, since both surfaces of the coupling flange 13 serve as positioning reference surfaces, both surfaces are machined to be precision planes.

[0034] [Method for manufacturing neutron focusing device] FIG. 4 is a diagram showing the flow of the method for manufacturing the neutron focusing device 1 of the present embodiment.

[0035] Step S10 is the underprocessing of the mirror segments 121. An aluminum alloy (for example, A5052) is processed to approximately the shape of the mirror segments 121. At this time, one unit's worth, that is, 12 mirror segments 121 are prepared simultaneously.

[0036] In step S20, electroless plating is performed on the pre-processed mirror segment 121 to deposit nickel-phosphorus on the aluminum alloy to a thickness of about 100 μm.

[0037] Step S30 is a cutting (turning) process for the mirror segment 121. In the cutting process, with the mirror segments 121 for one unit assembled in a cylindrical shape, the entire circumference of the surface where the super mirror metal multilayer film is provided is cut simultaneously.

[0038] FIG. 5 is a diagram for explaining the cutting process. Twelve mirror segments 121 for one unit are attached to a high-precision jig 501 for fixing the mirror segments 121 to the rotation axis of a lathe. The high-precision jig 501 is generally cylindrical and has a mounting surface 502 for the mirror segments at its end. The mounting surface 502 is provided with positioning pins and fastening parts, and the mirror segments 121 are attached accurately. Here, the inner surface of the flange portion 122 of the mirror segment 121 is attached to the mounting surface 502. With the mirror segments 121 for one unit assembled in this way, using a boring tool 510 provided with a diamond tool 511 at its tip, the inner surface of the mirror segment 121 is precisely turned so as to form a part of a predetermined curved surface shape. Also, the outer surface of the exposed flange portion 122 of the mirror segment 121 is simultaneously precision machined to a flat surface. Since the outer surface of this flange portion 122 becomes the mounting surface, high-precision machining is important.

[0039] Step S40 is a polishing process for the mirror segment 121. In the polishing process, with the mirror segments 121 for one unit assembled in a cylindrical shape, the surface where the super mirror metal multilayer film is provided is polished simultaneously.

[0040] FIG. 6 is a diagram for explaining polishing. When polishing the mirror segment 121 with a polishing apparatus 600, twelve mirror segments 121 for one unit are combined with a coupling flange 13 and assembled in a cylindrical shape. Specifically, the outer surface of the flange portion 122 precisely machined in the cutting process is attached to the coupling flange 13. Note that the mirror segment 121 may be attached to a jig for polishing instead of the coupling flange 13. The mirror segment 121 and the coupling flange 13 are placed on a rotary table 601, and while the rotary table 601 is slowly rotated by a motor 602, a polishing tool 603 is rotated at high speed to polish the inner surface of the mirror segment 121 so as to form a part of a predetermined curved surface shape. If the surface roughness of the inner surface of the mirror segment 121 in the cutting process is machined with an accuracy of 2 nm (rms), it can be polished to a surface roughness of about 0.2 nm (rms) using a colloidal silica abrasive. When the surface roughness in the cutting process exceeds 2 nm (rms), after polishing to a surface roughness of 2 nm (rms) using an abrasive such as alumina abrasive, polishing using colloidal silica can be performed to polish to a surface roughness of about 0.2 nm (rms).

[0041] In step S50, the polished mirror segment 121 is washed. The washing is simultaneously performed on the twelve mirror segments 121 for one unit while the mirror segments for one unit are assembled. The washing is, for example, scrub washing using a PVA (polyvinyl alcohol) sponge.

[0042] In step S60, a multilayer film super mirror (mirror portion) is formed on the inner surface of the mirror segment 121 (see Patent Document 1). The mirror segment 121 after cleaning is removed from the coupling flange 13, and at least one unit of the mirror segment 121 is placed on a flat substrate, and a super mirror multilayer film of nickel and titanium is formed on the surface by ion beam sputtering. By simultaneously performing the film forming process on one unit of the mirror segment 121, film formation under the same conditions becomes possible. Note that it is not limited to one unit, and a plurality of units of the mirror segment 121 may be simultaneously formed. However, by using a small film forming apparatus capable of simultaneously performing the film forming process on one unit of the mirror segment 121, the film forming conditions for each mirror segment 121 can be made more uniform. If the identity of the film forming conditions can be ensured or the error of the film forming conditions can be tolerated, the mirror segments 121 for one unit may be divided into several groups and the film forming process may be performed for each group.

[0043] In step S70, the mirror segment 121 on which the formation of the super mirror is completed is assembled together with the coupling flange 13 and the vacuum chamber 11 to form one elliptical mirror unit 10. Specifically, on the first region 131 on one surface of the coupling flange 13, the flange portion 122 of the mirror segment 121 is attached using the positioning pins 132 and the screw holes 133. Also, on the second region 134 on the same surface of the coupling flange 13, the first flange portion 112 of the vacuum chamber 11 is attached using the positioning pins 135 and the screw holes 136. Next, a plurality of units 10 are coupled to each other, and by attaching the lids 20 to the openings at both ends, the neutron focusing device 1 is completed. The coupling of the two units 10 is performed by attaching the second flange portion 113 of the vacuum chamber 11 of one unit and the coupling flange 13 of the other unit using the positioning pins 135 and the screw holes 136.

[0044] [Advantageous Effects of the Present Embodiment] In this embodiment, while the mirror segments 121 for the entire circumference of one unit divided in the circumferential direction are assembled, they are simultaneously machined by cutting (turning). By this cutting process, the mirror segments 121 for one unit are machined into a precise rotationally symmetric shape with a single axis of rotational symmetry in one processing. Also, not only cutting but also polishing and cleaning are simultaneously performed for the entire circumference of one unit. Thus, since the mirror segments are processed in a batch in the assembled state, this method is superior to the prior art in terms of both the accuracy and speed of processing.

[0045] Also, taking the mirror segments for the entire circumference divided in the axial direction as one unit, the mirror segments 121 belonging to one unit are positioned with respect to the coupling flange 13 and the vacuum chamber 11. Therefore, by preparing a plurality of such units and interconnecting them, the rotationally symmetric shape can be easily extended in the axial direction. For example, first, a neutron focusing device with several units connected is manufactured, and then units with additional mirror segments manufactured are added to enable axial expansion.

[0046] Also, by disassembling the mirror segments for one or more units and simultaneously depositing films in a state where they are arranged in a film deposition apparatus such as an ion beam sputtering apparatus, a neutron supermirror for the entire circumference can be obtained in one film deposition process.

Description of Reference Numerals

[0047] 1: Neutron focusing device 10: Rotationally elliptical mirror unit 11: Vacuum chamber 12: Mirror unit 13: Coupling flange

Claims

1. A neutron focusing device comprising a plurality of units connected in an axial direction and equipped with a neutron supermirror having a predetermined curved surface shape, Each of the plurality of units comprises: A plurality of mirror segments divided in a circumferential direction, each of which has a mirror portion that constitutes a part of the neutron supermirror having the predetermined curved surface shape; a vacuum chamber containing the plurality of mirror segments; a coupling flange to which the plurality of mirror segments and the vacuum chamber are attached; Equipped with Each of the plurality of mirror segments has a flange portion at one end, a first flange portion is provided at one end of the vacuum chamber and a second flange portion is provided at the other end; The coupling flange is provided with a first mounting portion for mounting the flange portions of a plurality of mirror segments of the same unit as the coupling flange, and a second mounting portion located on an outer periphery of the first mounting portion for mounting the first flange portion of a vacuum chamber of the same unit as the coupling flange. A neutron focusing device comprising:

2. The coupling flange is provided with a third mounting portion for mounting the second flange portion of a vacuum chamber of a unit different from the coupling flange.

2. The neutron focusing device according to claim 1 .

3. outer surfaces of the flange portions of the plurality of mirror segments, outer surfaces of the first flange portion and the second flange portion of the vacuum chamber, and both surfaces of the coupling flange are precision machined to be flat.

2. The neutron focusing device according to claim 1 .

4. A surface of revolution consisting of an ellipsoid, a paraboloid, or a hyperboloid, or a combination thereof, is formed by the multiple mirror segments of the multiple units.

2. The neutron focusing device according to claim 1 .

5. Each of the plurality of mirror segments has a metal multilayer film formed on an amorphous plating applied to a metal member.

2. The neutron focusing device according to claim 1 .

6. A method for manufacturing a neutron focusing device having a neutron supermirror having a predetermined curved surface shape and configured by connecting a plurality of units in an axial direction, comprising: Each of the plurality of units comprises: A plurality of mirror segments divided in a circumferential direction, the plurality of mirror segments having a mirror portion constituting a part of the neutron supermirror having the predetermined curved surface shape; a vacuum chamber containing the plurality of mirror segments; a coupling flange for coupling the plurality of mirror segments and the vacuum chamber; Equipped with The manufacturing method includes: a machining step of machining a surface of a metal member constituting one unit of assembled mirror segments so as to form a part of the predetermined curved shape; a deposition step of forming a multilayer supermirror on the surface of a plurality of mirror segments in a state where the mirror segments are placed; an assembly process in which a plurality of mirror segments and a vacuum chamber for one unit are attached to the coupling flange and the plurality of units are coupled together; A method for manufacturing a neutron focusing device, comprising:

7. Each of the plurality of mirror segments has a flange portion at one end, The processing step includes: a cutting step of cutting surfaces of the mirror segments while the inner surfaces of the flange portions of the plurality of mirror segments for one unit are attached to a first jig; a polishing step of polishing the surfaces of the mirror segments while the outer surfaces of the flange portions of the plurality of mirror segments for one unit are attached to the coupling flange or a second jig; A method for manufacturing a neutron focusing device according to claim 6, comprising:

8. In the cutting step, the outer surface of the flange portion is precisely machined to a flat surface. A method for manufacturing a neutron focusing device according to claim 7.

9. the assembling step includes a step of attaching the plurality of mirror segments and the vacuum chamber to one surface of the coupling flange; A method for manufacturing a neutron focusing device according to claim 6.

10. The assembly step includes a step of attaching the vacuum chamber of the first unit to the other surface of the coupling flange of the second unit. A method for manufacturing a neutron focusing device according to claim 9.

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