JP2020187871A - Internal surface treatment method for superconducting accelerated cavity, manufacturing method for superconducting accelerated cavity, and surface treatment method for superconducting material - Google Patents

Abstract

To provide an inner surface treatment method of a superconducting accelerating cavity, a manufacturing method of a superconducting accelerating cavity, and a surface treatment method of a superconducting material which can store nitrogen in the inner surface of the superconducting accelerating cavity without using a dedicated vacuum heat treatment furnace.SOLUTION: An inner surface treatment method of a superconducting accelerating cavity includes a high-pressure ultrapure water cleaning step of cleaning the inner surface 2 of an acceleration cavity 1, a suction step of vacuum-sucking the internal space of the sealed acceleration cavity 1 after cleaning, a heating step of arranging a heating heater 33 on the outer surface of the acceleration cavity 1 to heat the vacuum-suctioned acceleration cavity 1, and a nitrogen introduction step of introducing nitrogen into the internal space of the vacuum-suctioned and heated acceleration cavity 1.SELECTED DRAWING: Figure 2

Description

The present invention relates to a method for treating the inner surface of a superconducting accelerating cavity.

Generally, a superconducting accelerator that accelerates charged particles such as electrons and protons by a superconducting accelerating cavity is known. In this type of superconducting accelerator, microwaves are introduced into a superconducting accelerating cavity formed of a superconducting material (for example, niobium) to accelerate charged particles passing through the inside. In order for the superconducting accelerating cavity to exhibit the specified performance, the inner surface (inner surface) of the superconducting accelerating cavity must be kept very smooth and clean, and as a treatment method for that, for example, electrolysis Polishing can be mentioned (see Patent Document 1). In recent years, the development of a technique for improving superconducting characteristics by incorporating a small amount of nitrogen into the surface layer of the inner surface (inner surface) of the superconducting acceleration cavity has been promoted. After chemically polishing or electrolytic polishing the inner surface of the superconducting acceleration cavity, it is stored in a vacuum heat treatment furnace and heated, and nitrogen is introduced into the vacuum furnace while the temperature inside the furnace is lowered during or after heating. Nitrogen is occluded on the inner surface of the conduction acceleration cavity. As the final finish of the inner surface, a small amount of electrolytic polishing and high-pressure ultrapure water cleaning are performed.

Japanese Patent No. 2947270

In the above method of occluding nitrogen on the inner surface of the superconducting acceleration cavity, a clean atmosphere is required when introducing nitrogen, so the cleanliness is insufficient in a general vacuum heat treatment furnace, for example, oil-free. Dedicated equipment using an exhaust system is required.

The present invention has been made in view of the above, and is a method for treating the inner surface of a superconducting accelerating cavity, which can occlude nitrogen on the inner surface of the superconducting accelerating cavity without using a dedicated vacuum heat treatment furnace. It is an object of the present invention to provide a method for producing an accelerating cavity and a method for surface treatment of a superconducting material.

In order to solve the above-mentioned problems and achieve the object, the present invention is a method for treating the inner surface of a superconducting accelerating cavity formed in a tubular shape by a superconducting material. A cleaning step of cleaning the inner surface of the superconducting acceleration cavity, a suction step of vacuum-sucking the internal space of the sealed superconducting acceleration cavity after cleaning, and heating the vacuum-suctioned superconducting acceleration cavity from the outer surface of the superconducting acceleration cavity. It is characterized by including a heating step and a nitrogen introduction step of introducing nitrogen into the internal space of the superconducting acceleration cavity heated by vacuum suction.

In this configuration, the heating step may heat the superconducting accelerating cavity to 120 ° C. or higher and 250 ° C. or lower.

Further, the present invention is a method for treating the inner surface of a superconducting accelerating cavity formed in a tubular shape by a superconducting material, wherein the irradiation head for irradiating a laser beam is a superconducting accelerating cavity. A suction step of vacuum-sucking the internal space while inserted into the internal space, and moving at least one of the irradiation head and the superconducting acceleration cavity to irradiate the inner surface of the vacuum-sucked superconducting acceleration cavity with laser light. It is characterized by including a laser cleaning step of cleaning the inner surface thereof and a nitrogen introduction step of introducing nitrogen into the internal space of the superconducting accelerating cavity in parallel with irradiation of the laser beam.

Further, the present invention is a method for assembling a superconducting accelerating cavity formed in a tubular shape by a superconducting material and manufacturing a superconducting accelerating cavity for processing the inner surface, in an internal space of a component constituting the superconducting accelerating cavity. With the irradiation head that irradiates the laser beam inserted, at least one of the irradiation head and the superconducting acceleration cavity is moved, and the inner surface of the joint portion of the parts of the superconducting acceleration cavity is irradiated with the laser beam to join the joint. It is characterized by including a laser welding step of welding a portion and a nitrogen introducing step of introducing nitrogen into the internal space of the superconducting accelerating cavity in parallel with irradiation of laser light. In this configuration, the laser welding step may be performed from the outer surface of the superconducting acceleration cavity.

Further, the present invention is a surface treatment method for a superconducting material that is to be formed into a tubular shape, and the superconducting material is irradiated with an electron beam on an ore containing the superconducting material in a vacuum suction environment. A refining step including a refining step of rolling a refined superconducting material and then cutting it into a predetermined shape, and a heat treatment step of heat-treating the cut superconducting material in a vacuum-sucked environment. And when performing at least one of the heat treatment steps, it is characterized by introducing nitrogen into the vacuum sucked environment.

According to the present invention, nitrogen can be occluded on the inner surface of the superconducting acceleration cavity without using a dedicated vacuum heat treatment furnace.

FIG. 1 is a flowchart showing a procedure of an inner surface treatment method for a superconducting accelerating cavity according to the first embodiment. FIG. 2 is a diagram showing a suction step, a heating step, and a nitrogen introduction step of the inner surface treatment method of the superconducting acceleration cavity. FIG. 3 is a flowchart showing the procedure of the inner surface treatment method of the superconducting acceleration cavity according to the second embodiment. FIG. 4 is a diagram showing a laser cleaning step of a method for treating the inner surface of a superconducting accelerated cavity. FIG. 5 is a flowchart showing a procedure of a method for manufacturing a superconducting accelerating cavity according to a third embodiment. FIG. 6 is a diagram showing a laser welding process of a method for manufacturing a superconducting accelerated cavity. FIG. 7 is a flowchart showing the procedure of the surface treatment method of the superconducting material constituting the superconducting accelerating cavity according to the fourth embodiment.

An embodiment (embodiment) for carrying out the present invention will be described in detail with reference to the drawings. The present invention is not limited to the contents described in the following embodiments. In addition, the components described below include those that can be easily assumed by those skilled in the art and those that are substantially the same. Further, the configurations described below can be combined as appropriate. In addition, various omissions, substitutions or changes of the configuration can be made without departing from the gist of the present invention.

[First Embodiment]
The method for treating the inner surface of the superconducting accelerating cavity according to the first embodiment will be described. FIG. 1 is a flowchart showing a procedure of an inner surface treatment method for a superconducting accelerating cavity according to the first embodiment. FIG. 2 is a diagram showing a suction step, a heating step, and a nitrogen introduction step of the inner surface treatment method of the superconducting acceleration cavity.

As shown in FIG. 1, the method for treating the inner surface of the superconducting accelerated cavity according to the first embodiment includes an accelerated cavity forming step S11, an electrolytic polishing step (polishing step) S12, and a high-pressure ultrapure water cleaning step (cleaning step). S13, a suction step S14, a heating step S15, and a nitrogen introduction step S16 are provided. As shown in FIG. 2, the acceleration cavity (superconducting acceleration cavity) 1 is a structure in which a plurality (for example, nine) of substantially cylindrical cells 3 having a bulging central portion are combined in the axial direction. The acceleration cavity 1 is formed into a predetermined shape by, for example, bending a niobium (Nb) material which is a superconducting material, press molding, electron beam welding, laser welding, or other welding (step S11: acceleration). Cavity forming process).

Next, as a treatment of the inner surface 2 of the acceleration cavity 1, first, an electrolytic polishing step is performed (step S12). The electrolytic polishing step S12 is performed to remove impurities in the material of the acceleration cavity 1 and remove deposits on the inner surface 2 of the acceleration cavity 1, and is carried out using, for example, the apparatus or method shown in Japanese Patent No. 2947270. To.

When the electrolytic polishing step S12 is completed, a high-pressure ultrapure water cleaning step (cleaning step) is performed in order to remove foreign substances adhering to the inner surface 2 of the acceleration cavity 1 (step S13). The high-pressure ultrapure water cleaning step S13 is carried out using, for example, the apparatus or method shown in Japanese Patent No. 55355772.

When the high-pressure ultrapure water cleaning step S13 is completed, a suction step (step S14), a heating step (step S15), and a nitrogen introduction step (step S16) are subsequently carried out. Each of these steps is carried out by the heat treatment apparatus 31 as shown in FIG. Caps 17 for preventing (sealing) leakage of fluids such as liquids and gases are attached to both open ends 1A and 1B of the acceleration cavity 1, respectively.

The heat treatment device 31 introduces a vacuum suction device 32 that vacuum sucks the inside of the acceleration cavity 1, a heating heater 33 that is arranged on the outer surface of the acceleration cavity 1 and heats the acceleration cavity 1, and nitrogen inside the acceleration cavity 1. The nitrogen introduction device 34 is provided. The vacuum suction device 32 is an oil-free vacuum pump that does not use lubricating oil, and is connected to a suction pipe 35 that communicates with one open end 1B of the acceleration cavity 1 through a cap 17. In the present embodiment, since the exhaust space is limited to the inside of the acceleration cavity 1, a large dedicated facility such as a cryopump is not required, and suction by a vacuum pump smaller than the cryopump is possible. For example, an electric heater is used as the heating heater 33, and the heating heater 33 is wound so as to cover the outer surface of the acceleration cavity 1. The means for heating is not limited to the heater, and a well-known heating means can be used as long as the acceleration cavity 1 can be heated from the outer surface of the acceleration cavity 1. The nitrogen introduction device 34 has, for example, a pressurized container (cylinder) holding nitrogen gas, and is connected to an introduction pipe 36 communicating with the other open end 1A of the acceleration cavity 1 through a cap 17.

In the suction step S14, the vacuum suction device 32 vacuum-sucks the internal space of the acceleration cavity 1 and makes the inside of the acceleration cavity 1 have a pressure of, for example, about 1 × 10 ^-2 Pa. At this time, since the external space of the acceleration cavity 1 is at atmospheric pressure, only the internal space of the acceleration cavity 1 is evacuated. Further, in the heating step S15, the heating heater 33 is adjusted so that the temperature of the acceleration cavity 1 is, for example, in the range of 120 ° C. or higher and 250 ° C. or lower.

By these suction step S14 and heating step S15, the gas (for example, hydrogen) occluded in the inner surface 2 (niobium material) of the acceleration cavity 1 can be separated from the inner surface 2 and removed. Subsequently, the nitrogen introduction step S16 for introducing the nitrogen gas into the internal space of the vacuum suction and the heated acceleration cavity 1 is carried out. The suction step S14, the heating step S15, and the nitrogen introduction step S16 are carried out in parallel. In the nitrogen introduction step S16, the nitrogen introduction device 34 takes a predetermined time (for example, 2 minutes or more and 48 hours or less) so that the pressure in the internal space of the acceleration cavity 1 vacuum-sucked becomes, for example, 3 Pa. Continue to introduce nitrogen. As a result, nitrogen gas can be easily occluded on the inner surface 2 (niobium material) of the acceleration cavity 1. When the nitrogen introduction step S16 is completed, the suction step S14 and the heating step S15 are completed, and the operation of the inner surface treatment method for the superconducting acceleration cavity according to the first embodiment is completed.

According to the first embodiment, the high-pressure ultrapure water cleaning step S13 for cleaning the inner surface 2 of the acceleration cavity 1 and the suction step S14 for vacuum-sucking the internal space of the accelerated cavity 1 sealed after cleaning are vacuum-sucked. A heating step S15 in which a heating heater 33 is arranged on the outer surface of the acceleration cavity 1 to heat the acceleration cavity 1 from the outer surface, and a nitrogen introduction step S16 for introducing nitrogen into the internal space of the vacuum suction and heated acceleration cavity 1 are performed. Therefore, nitrogen can be easily occluded in the inner surface 2 of the clean acceleration cavity 1 after the high-pressure ultrapure water cleaning step S13. Further, in the heating step S15, since the heating heater 33 can be arranged on the outer surface of the acceleration cavity 1 to heat the vacuum-suctioned acceleration cavity, it is not necessary to use a dedicated vacuum heat treatment furnace, and the apparatus configuration can be miniaturized and simplified. Can be realized.

Further, according to the first embodiment, since the heating step S15 heats the acceleration cavity 1 to 120 ° C. or higher and 250 ° C. or lower, the acceleration cavity 1 can be heated to a desired temperature with a simple configuration using the heating heater 33. ..

[Second Embodiment]
Next, a method for treating the inner surface of the superconducting accelerating cavity according to the second embodiment will be described. FIG. 3 is a flowchart showing the procedure of the inner surface treatment method of the superconducting acceleration cavity according to the second embodiment. FIG. 4 is a diagram showing a laser cleaning step of a method for treating the inner surface of a superconducting accelerated cavity. As shown in FIG. 3, the method for treating the inner surface of the superconducting accelerating cavity according to the second embodiment includes an accelerating cavity forming step S21, an electrolytic polishing step (polishing step) S22, a suction step S23, and a laser cleaning step S24. , The nitrogen introduction step S25 is provided. Since the accelerated cavity forming step S21 and the electrolytic polishing step S22 are equivalent to the accelerated cavity forming step S1 and the electrolytic polishing step S12, the description thereof will be omitted.

When the electrolytic polishing step S22 is completed, a suction step (step S23), a laser cleaning step (step S24), and a nitrogen introduction step (step S25) are subsequently carried out. Each of these steps is carried out by the laser cleaning device 40 as shown in FIG. The laser cleaning device 40 includes a pair of rotation holders 6 that rotatably hold the acceleration cavity 1 around an axis, and a rotation device 7 that rotates the rotation holder 6. Each of the pair of rotation holders 6 has a disk shape, holds an axial end portion of the acceleration cavity 1, and is connected by a holding shaft 12. Gears 13 having teeth engraved on the outer periphery are provided on the facing surfaces of the pair of rotation holders 6. The rotating device 7 includes a pair of gears 14 that mesh with each gear 13, a rotating shaft 15 that connects the gears 14, and a motor 16 that rotates the rotating shaft 15.

Further, the laser cleaning device 40 includes a vacuum suction device 32 that vacuum-sucks the inside of the acceleration cavity 1, a nitrogen introduction device 34 that introduces nitrogen into the acceleration cavity 1, a laser oscillation device 41 that oscillates laser light, and the like. An optical fiber cable 42 connected to the laser oscillation device 41 and an irradiation head 43 arranged at the tip of the optical fiber cable 42 are provided. Since the configurations of the vacuum suction device 32 and the nitrogen introduction device 34 are the same as those described above, the same reference numerals are given and the description thereof will be omitted.

The irradiation head 43 includes a mirror and a lens (not shown), and the mirror changes the angle of the laser beam 43A incident through the optical fiber cable 42 toward the inner surface 2 of the acceleration cavity 1. The lens focuses the laser beam 43A on the inner surface 2 of the acceleration cavity 1. The optical fiber cable 42 is inserted into the acceleration cavity 1 through the cap 17, and the irradiation head 43 is movably configured along the axial direction (arrow A direction) of the acceleration cavity 1.

Laser cleaning is a processing process that utilizes the evaporation of substances by irradiating laser light. By irradiating the outermost surface layer of the inner surface 2 of the acceleration cavity 1 with the laser beam 43A, microplasma is generated on the inner surface 2, and the contaminated layer (corrosion layer, contaminated layer, etc.) of the inner surface 2 is generated by the shock wave and the coefficient of thermal expansion. Evaporates and removes foreign matter such as coating layer and coating layer. The removed foreign matter is sucked by the vacuum suction device 32 and discharged to the outside of the acceleration cavity 1.

In the suction step S23, the vacuum suction device 32 vacuum-sucks the internal space of the acceleration cavity 1, and sets the pressure inside the acceleration cavity 1 to, for example, about 1 × 10 ^-2 Pa. At this time, since the external space of the acceleration cavity 1 is at atmospheric pressure, only the internal space of the acceleration cavity 1 is evacuated. Further, in the laser cleaning step S24, the irradiation head 43 irradiates the laser beam 43A toward the inner surface 2 of the acceleration cavity 1. At this time, by moving the irradiation head 43 along the axial direction and rotating the acceleration cavity 1, the entire inner surface 2 can be cleaned by irradiating the laser beam 43A over the entire inner surface 2 of the acceleration cavity 1. it can. Both the irradiation head 43 and the acceleration cavity 1 may be moved so that the laser beam 43A can be irradiated on the entire inner surface 2 of the acceleration cavity 1. Further, the acceleration cavity 1 may be fixed and the irradiation head 43 may be rotated. Further, the foreign matter on the inner surface 2 may be removed by pinpointing a specific portion instead of the entire inner surface 2 of the acceleration cavity 1.

Since the acceleration cavity 1 is heated by irradiating the inner surface 2 of the acceleration cavity 1 with the laser beam 43A, the gas (for example, hydrogen) occluded in the inner surface 2 of the acceleration cavity 1 is separated from the inner surface 2 and removed. Can be done. Subsequently, the nitrogen introduction step S25 for introducing nitrogen gas into the internal space of the accelerated cavity 1 that has been vacuum-sucked and laser-cleaned is carried out. The suction step S23, the laser cleaning step S24, and the nitrogen introduction step S25 are performed in parallel. In the nitrogen introduction step S25, the nitrogen introduction device 34 takes a predetermined time (for example, 2 minutes or more and 48 hours or less) so that the pressure in the internal space of the acceleration cavity 1 vacuum-sucked becomes, for example, 3 Pa. Continue to introduce nitrogen. As a result, nitrogen gas can be easily occluded on the inner surface 2 (niobium material) of the acceleration cavity 1. When the nitrogen introduction step S25 is completed, the suction step S23 and the laser cleaning step S24 are completed, and the operation of the inner surface treatment method for the superconducting accelerating cavity according to the second embodiment is completed.

According to the second embodiment, the suction step S23 in which the irradiation head 43 that irradiates the laser beam 43A is inserted into the internal space of the acceleration cavity 1 and the internal space is vacuum-sucked, and the irradiation head 43 and the acceleration cavity 1 A laser cleaning step S24 in which at least one is moved to irradiate the inner surface 2 of the accelerating cavity 1 that has been evacuated with a laser beam 43A to clean the inner surface 2, and the acceleration cavity 1 in parallel with the irradiation of the laser beam 43A. Since the nitrogen introduction step S25 for introducing nitrogen into the internal space is provided, nitrogen can be occluded in the inner surface 2 at the same time as cleaning the inner surface 2 of the acceleration cavity 1. Further, since the inner surface 2 of the acceleration cavity 1 is cleaned in the laser cleaning step S24, for example, the cleaning step using ultrapure water can be omitted, and the work process can be simplified and the amount of drainage can be reduced. Further, by irradiating the laser beam 43A in the laser cleaning step S24, only the surface layer of the vacuum-suctioned acceleration cavity 1 can be heated, so that it is not necessary to use a dedicated vacuum heat treatment furnace, and the device configuration can be miniaturized and simplified. Can be realized.

In the second embodiment described above, the configuration in which the high-pressure ultrapure water cleaning step (cleaning step) is omitted by carrying out the laser cleaning step S24 has been described, but the high-pressure ultrapure water cleaning step and ultrasonic cleaning (cleaning) Of course, the cleaning step) may be carried out.

[Third Embodiment]
Next, a method of assembling the superconducting accelerating cavity according to the third embodiment and manufacturing a superconducting accelerating cavity for treating the inner surface will be described. FIG. 5 is a flowchart showing a procedure of a method for manufacturing a superconducting accelerating cavity according to a third embodiment. FIG. 6 is a diagram showing a laser welding process of a method for manufacturing a superconducting accelerated cavity. As shown in FIG. 5, the method for manufacturing the superconducting accelerating cavity according to the third embodiment includes a suction step S31, a laser welding step S32, and a nitrogen introduction step S33. In the second embodiment described above, nitrogen was occluded on the inner surface 2 by utilizing the heating of the acceleration cavity 1 accompanying the laser irradiation in the laser cleaning step S24, but in the third embodiment, the laser welding step S32 Nitrogen is occluded on the inner surface 2 by utilizing the heating of the acceleration cavity 1 accompanying the laser irradiation.

Each step of the suction step S31, the laser welding step S32, and the nitrogen introduction step S33 is carried out by the laser welding apparatus 50 as shown in FIG. The laser welding device 50 includes the pair of rotation holders 6 and the rotation device 7 described above. Since the configurations of the rotary holder 6 and the rotary device 7 are the same as those described above, the same reference numerals are given and the description thereof will be omitted.

Further, the laser welding device 50 includes a vacuum suction device 32 that vacuum sucks the inside of the acceleration cavity 1, a nitrogen introduction device 34 that introduces nitrogen into the inside of the acceleration cavity 1, and a laser oscillation device 51 that oscillates laser light. An optical fiber cable 52 connected to the laser oscillation device 51 and an irradiation head 53 arranged at the tip of the optical fiber cable 52 are provided. Since the configurations of the vacuum suction device 32 and the nitrogen introduction device 34 are the same as those described above, the same reference numerals are given and the description thereof will be omitted.

The plurality of cells 3 constituting the acceleration cavity 1 are formed by combining two half cells (parts) 60 and 60, respectively. The half cell 60 has a bowl-like shape provided with a large-diameter opening and a small-diameter opening, and the cell 3 is welded to each other with the large-diameter openings of the two half-cells 60 at a joint portion 62. Further, in the acceleration cavity 1, the small diameter openings of the plurality of cells 3 are welded to each other at the joint portion 63, and the small diameter openings of the cells 3 at both ends and the cylindrical opening cylinder (part) 61 are welded to each other at the joint portion 64, respectively. Will be welded.

The irradiation head 53 includes a mirror and a lens (not shown), and the mirror makes an angle of the laser beam 53A incident through the optical fiber cable 52 toward the joints 62, 63, 64 of the acceleration cavity 1. Change. The lens focuses the laser beam 53A on the junctions 62, 63, 64 of the acceleration cavity 1. The optical fiber cable 52 is inserted into the acceleration cavity 1 through the cap 17, and the irradiation head 53 is movably configured along the axial direction (arrow A direction) of the acceleration cavity 1.

In the laser welding step S32 of the present embodiment, the joint portions 62, 63, 64 are welded from the inside of the acceleration cavity 1. Therefore, the acceleration cavity 1 is supported by the rotation holder 6, and before the suction step S31 is performed, the half cell 60 and the opening cylinder 61 are joined from the outside to form the acceleration cavity 1.

In the suction step S31, the vacuum suction device 32 vacuum-sucks the internal space of the acceleration cavity 1, and sets the inside of the acceleration cavity 1 to, for example, a pressure of 1 × 10 ^-2 Pa. At this time, since the external space of the acceleration cavity 1 is at atmospheric pressure, only the internal space of the acceleration cavity 1 is evacuated. Further, in the laser welding step S32, the irradiation head 53 positions the laser beam 53A at a position facing any of the joints 62, 63, 64 of the acceleration cavity 1 and irradiates the laser beam 53 toward the facing joints. At this time, by rotating the acceleration cavity 1, the joint portion can be welded by irradiating the joint portion with the laser beam 53A over the circumferential direction of the acceleration cavity 1. When the welding of one joint is completed, the irradiation head 53 is moved to a position facing the adjacent joint. Both the irradiation head 53 and the acceleration cavity 1 may be moved so that the laser beam 53A can be irradiated to each joint of the acceleration cavity 1.

Since the acceleration cavity 1 is heated by irradiating the joint portions 62, 63, and 64 of the acceleration cavity 1 with the laser beam 53A and welding them, the gas (for example, hydrogen) stored in the inner surface 2 of the acceleration cavity 1 is heated. Can be separated from the inner surface 2 and removed. Subsequently, the nitrogen introduction step S33 for introducing nitrogen gas into the internal space of the acceleration cavity 1 vacuum-sucked and laser-welded is carried out. The suction step S31, the laser welding step S32, and the nitrogen introduction step S33 are carried out in parallel. In the nitrogen introduction step S33, the nitrogen introduction device 34 takes a predetermined time (for example, 2 minutes or more and 48 hours or less) so that the pressure in the internal space of the acceleration cavity 1 vacuum-sucked becomes, for example, 3 Pa. Continue to introduce nitrogen. As a result, nitrogen gas can be easily occluded on the inner surface 2 (niobium material) of the acceleration cavity 1. When the nitrogen introduction step S33 is completed, the suction step S31 and the laser welding step S32 are completed. After that, a polishing step of chemically polishing or electrolytically polishing the inner surface 2 of the formed accelerated cavity 1, a cleaning step of ultrasonically cleaning and high-pressure ultrapure water cleaning of the polished inner surface 2, and heating the accelerated cavity 1 to a predetermined temperature. The heat treatment step of heat treatment (annealing and baking) may be carried out.

According to the third embodiment, the half cell 60 and the opening cylinder 61 constituting the acceleration cavity 1 are assembled, and the internal space is evacuated with the irradiation head 53 for irradiating the laser beam 53A inserted into the internal space of the acceleration cavity 1. In the suction step S31 for suction, at least one of the irradiation head 53 and the acceleration cavity 1 is moved, and the half cells 60 of the acceleration cavity 1 vacuum-sucked and the joints 62 between the half cells 60 and the opening cylinder 61, The laser welding step S32 in which the inner surfaces of 63 and 64 are irradiated with the laser beam 53A to weld the joint portions 62, 63 and 64, and the nitrogen that introduces nitrogen into the internal space of the acceleration cavity 1 in parallel with the irradiation of the laser beam 53A. Since the introduction step S33 is provided, nitrogen can be occluded on the inner surface 2 of the acceleration cavity 1 at the same time as the welding process of the acceleration cavity 1. Further, since the vacuum-suctioned acceleration cavity 1 can be heated by irradiating the laser beam 53A in the laser welding step S32, it is not necessary to use a dedicated vacuum heat treatment furnace, and the device configuration can be miniaturized and simplified. it can.

Further, in the present embodiment, it has been described that the half cell 60 and the opening cylinder 61 are joined from the outside to form the acceleration cavity 1 before the suction step S31 is carried out. While holding the 61 in the state of being assembled in the shape of the acceleration cavity 1, the laser welding step S32 may be carried out in a vacuum environment by putting the 61 into the vacuum chamber as it is. At this time, the laser welding step S32 may be performed by irradiating each joint portion with the laser beam 53A not only from the inside of the acceleration cavity 1 but also from the outside of the acceleration cavity 1.

Further, the acceleration cavities 1 formed in the present embodiment may be combined with the above-described steps of the first embodiment and the second embodiment. At this time, since nitrogen is occluded on the inner surface 2 of the acceleration cavity 1, the time of the nitrogen introduction step in each embodiment can be shortened.

[Fourth Embodiment]
FIG. 7 is a flowchart showing the procedure of the surface treatment method of the superconducting material constituting the superconducting accelerating cavity according to the fourth embodiment. In the fourth embodiment, nitrogen is introduced into the superconducting material (niobium) constituting the acceleration cavity 1 in advance, and nitrogen is occluded on the surface.

As shown in FIG. 7, the superconducting material includes a pressing step S41 for compressing an ore (crude material) containing the superconducting material, a refining step S42 for refining the ore, a forging step S43 for forging the purified superconducting material, and forging. Crushing step S44 for crushing the superconducting material, rolling step S45 for rolling the crushed superconducting material, cutting step S46 for cutting the rolled superconducting material into a predetermined shape, and heat treatment by heating the cut superconducting material ( It is formed by comprising a heat treatment step S47 for annealing) and a polishing step S48 for polishing the surface of the heat-treated superconducting material.

Among these, in the purification step S42, impurities (oxygen, carbon, etc.) contained in the ore are melted by irradiating the ore containing the superconducting material with an electron beam in a vacuum environment such as a vacuum chamber. Is released and purified. Since it is heated by irradiating it with an electron beam, it is possible to make a superconducting material in which nitrogen is occluded on the surface by introducing (adding) nitrogen into the vacuum chamber.

Further, also in the heat treatment step S47, since the material is heated to a predetermined temperature (about 730 ° C.) in a vacuum environment such as a vacuum chamber, by introducing nitrogen into the vacuum chamber, nitrogen is occluded on the surface of the superconductivity. You can make materials. In the present embodiment, nitrogen is introduced in the purification step S42 and the heat treatment step S47, but either one may be introduced. In this way, after the acceleration cavity 1 is formed using the superconducting material in which nitrogen is occluded, the inner surface 2 of the formed acceleration cavity 1 is chemically polished or electropolished, and the polished inner surface 2 is ultrasonically polished. A cleaning step of cleaning and high-pressure ultrapure water cleaning, and a heat treatment step of heating the acceleration cavity 1 to a predetermined temperature and performing heat treatment (annealing and baking) may be performed.

According to this fourth embodiment, in a vacuum environment, a purification step S42 of irradiating a superconducting material with an electron beam to purify an ore containing the superconducting material, and a predetermined shape after rolling the purified superconducting material. A cutting step S46 for cutting the material and a heat treatment step S47 for heat-treating the cut superconducting material in a vacuum environment are provided, and nitrogen is added to the vacuum environment when at least one of the purification step S42 and the heat treatment step S47 is performed. For introduction, a superconducting material in which nitrogen is stored can be made. Therefore, when the acceleration cavity 1 is formed by using this superconducting material, the steps of the first to third embodiments described above may be combined with the acceleration cavity 1. According to this configuration, since nitrogen is occluded in the superconducting material, it is not necessary to occlude nitrogen on the inner surface 2 or the processing time is shortened when the first to third embodiments are carried out. Can be realized.

The present invention is not limited to the above embodiment. That is, it can be modified in various ways without departing from the gist of the present invention. For example, the device configuration for carrying out each step of the above-described embodiment is an example, and may be carried out using another device.

1 Acceleration cavity (superconducting acceleration cavity)
2 Inner surface 3 Cell 17 Cap 32 Vacuum suction device 33 Heating heater (heating means)
34 Nitrogen introduction device 40 Laser cleaning device 43 Irradiation head 43A Laser light 50 Laser welding device 53 Irradiation head 53A Laser light 60 Half cell (parts)
61 Opening cylinder (parts)
62, 63, 64 joints

Claims (5)

A method for treating the inner surface of a superconducting accelerating cavity formed in a tubular shape by a superconducting material.
A cleaning step for cleaning the inner surface of the superconducting acceleration cavity, and
A suction process that vacuum-sucks the internal space of the superconducting acceleration cavity that is sealed after cleaning,
A heating step of heating the vacuum-sucked superconducting accelerating cavity from the outer surface of the superconducting accelerating cavity,
A nitrogen introduction step of introducing nitrogen into the internal space of the superconducting acceleration cavity heated by vacuum suction and
A method for treating the inner surface of a superconducting accelerating cavity, which comprises. The method for treating the inner surface of a superconducting accelerating cavity according to claim 1, wherein the heating step heats the superconducting accelerating cavity to 120 ° C. or higher and 250 ° C. or lower. A method for treating the inner surface of a superconducting accelerating cavity formed in a tubular shape by a superconducting material.
A suction step of vacuum-sucking the internal space with the irradiation head that irradiates the laser beam inserted into the internal space of the superconducting acceleration cavity.
A laser cleaning step of moving at least one of the irradiation head and the superconducting accelerating cavity to irradiate the inner surface of the vacuum-suctioned superconducting accelerating cavity with the laser beam to clean the inner surface.
A nitrogen introduction step of introducing nitrogen into the internal space of the superconducting acceleration cavity in parallel with the irradiation of the laser beam,
A method for treating the inner surface of a superconducting accelerating cavity, which comprises. A method for assembling a superconducting accelerating cavity formed in a tubular shape by a superconducting material and manufacturing a superconducting accelerating cavity for treating the inner surface.
With the irradiation head that irradiates the laser beam inserted into the internal space of the component that constitutes the superconducting acceleration cavity, at least one of the irradiation head and the superconducting acceleration cavity is moved to form the superconducting acceleration cavity. A laser welding step of irradiating the inner surface of the joint portion of the component with the laser beam to weld the joint portion.
A nitrogen introduction step of introducing nitrogen into the internal space of the superconducting acceleration cavity in parallel with the irradiation of the laser beam,
A method for manufacturing a superconducting accelerating cavity, which comprises. A surface treatment method for superconducting materials that are about to be formed into a tubular shape.
A purification step of irradiating an ore containing the superconducting material with an electron beam to purify the superconducting material in a vacuum-suctioned environment.
A cutting process in which the refined superconducting material is rolled and then cut into a predetermined shape.
A heat treatment step of heat-treating the cut superconducting material in a vacuum-sucked environment is provided.
A method for surface-treating a superconducting material, which comprises introducing nitrogen into the vacuum-sucked environment when at least one of the purification step and the heat treatment step is carried out.

Images