JP2000260599A - Superconducting cavity, its manufacture, and superconducting accelerator - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a high-quality superconducting cavity without welding defects, a manufacturing method of the superconducting cavity, and a superconducting accelerator made up of the superconducting cavity. SOLUTION: In welding a cavity 1 by using laser light, the entire cavity 1 is set in a vessel 5, both air in the cavity 1 and air in the container 5 are evacuated with optical heads 6, 7 for condensing the laser light inserted inside the cavity 1, then the atmospheres outside and inside the cavity 1 are changed into high-purity inert gas atmospheres of the same pressure by inletting an inert gas, and the cavity 1 is welded by the laser light under these conditions.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to a superconducting cavity, a method of manufacturing the same, and a superconducting accelerator.

[0002]

2. Description of the Related Art Conventionally, electron beam welding is often used for welding and assembling cavities made of oxygen-free copper or niobium. In this case, the iris and the cell are welded from outside the cavity.

[0003]

Problems to be Solved by the Invention
No. 0, "Method of manufacturing an acceleration tube" describes a method characterized by irradiating a YAG laser beam to the inner surface of a joint to melt the vicinity of the inner surface of the joint, and to inactivate the inside of the accelerator. It states that a gas atmosphere is used.
However, the specific method cannot be read at all from the figures in this publication, and welding is impossible only with a YAG laser beam obtained from an optical fiber. Therefore, in this case, some complicated optical system and drive system are required.

FIGS. 10A and 10B are views showing a state of high energy beam welding according to the conventional method. FIG. 10A shows a normal high energy beam welding cross-sectional shape 59, and FIG. Numerals 60 and (c) show an undercut welding cross-sectional shape 61 due to burn-through.

[0005] In conventional electron beam welding, since the welding is performed from the outer periphery, penetration welding is fundamental. Therefore, if even a slight gap is formed in the groove, a convex back bead occurs as shown in FIG. 10A, or a fusion failure occurs due to the groove gap as shown in FIG. 10B. In addition, there is a possibility that the welded portion may be melted down and become an undercut weld bead as shown in FIG.

On the other hand, in the case of laser welding, welding is usually performed while supplying an inert gas from the side to be irradiated with laser light. However, in the case of an active metal such as niobium or oxygen-free copper, or a material which is easily oxidized. Insufficient antioxidant shielding can be provided. In addition, since the back side is usually not in an inert gas atmosphere, in the case of such a metal, an inert gas atmosphere of some kind must be sufficiently formed.

In the case of laser welding, since the shape is basically the same as the shape of the welding bead of the electron beam, similar defects may occur when welding is performed from the outer periphery with laser light. For this reason, when welding with laser light, it is considered appropriate to perform welding from inside the cell portion and the iris portion. One of the technical issues is to develop a compact optical system including such a small-diameter tube inner diameter and a drive unit.

[0008] Further, since the inside diameter of the inner welded portion is greatly different, a single optical system cannot cope with it, and at least two or more types of optical systems are required. However, it is difficult to pass two types of optical systems through an iris component having a small inner diameter. Optical control is required, including a method of controlling and positioning these two types of optical systems at appropriate positions.

Further, the roundness of the inner diameter of the iris portion and the cell portion is eccentric with respect to the center axis even if the end face is machined because the product is a pressed product. In this case, it is necessary to develop a method of remotely controlling the position of the focal point of the laser beam and controlling the deviation of the welding line.

When performing laser welding, two types of methods can be considered. The welding is performed not through through from inside but through through, and the cavity is rotated or the optical system is rotated to perform non-through welding from the outer periphery, but these are greatly different in the drive system. That is, an optimal drive system capable of high-precision positioning is required.

Usually, the material used for the cavity is niobium. Since this niobium is very expensive, when forming the base material from oxygen-free copper, welding of oxygen-free copper is usually difficult by laser welding. Therefore, it is necessary to develop a method for laser welding oxygen-free copper, and also to develop a method for making the surface of the oxygen-free copper inner surface niobium.

An object of the present invention is to provide a high-quality superconducting cavity free from welding defects, a method for manufacturing the superconducting cavity,
And a superconducting accelerator constituted by the superconducting cavity.

[0013]

In order to solve the above-mentioned problems and achieve the object, a superconducting cavity, a method for manufacturing the same, and a superconducting accelerator according to the present invention are configured as follows.

(1) In the method for manufacturing a superconducting cavity according to the present invention, when welding is performed using laser light, the entire cavity is set in a container, and the optical head for condensing the laser light is placed inside the cavity. In the inserted state, air in both the cavity and the container is sucked, and then the inert gas is sucked in, and the atmosphere outside and inside the cavity is made an inert gas atmosphere of high purity and the same pressure. Welding by the laser light.

(2) The method of manufacturing a superconducting cavity according to the present invention is the method described in (1) above, wherein a straight pipe is manufactured by bending a plate material, and is fixed by a jig from the inside of the straight pipe. And weld.

(3) The method for manufacturing a superconducting cavity according to the present invention is the method described in (2) above, wherein the welding of the straight pipe and the welding of the iris portion and the cell portion are performed by laser light from the inside. It is performed by non-penetration welding using a laser beam from outside as well as through welding.

(4) The method for manufacturing a superconducting cavity according to the present invention is the method as described in (2) above, wherein the welding of the straight pipe and the welding of the iris portion and the cell portion are performed by laser light from the inside. Performed by welding.

(5) The method of manufacturing a superconducting cavity according to the present invention is the method described in (3) or (4) above, and the welding groove between the iris portion and the cell portion has a stepped shape. .

(6) The method of manufacturing a superconducting cavity according to the present invention is the method according to any one of the above (3) to (5), and further comprises a step of welding a laser beam when welding the iris portion and the cell portion. After the temporary welding of the spot welding by the above or the temporary welding at the welding depth of 1.5 mm or less, the main welding is performed.

(7) The method of manufacturing a superconducting cavity according to the present invention is the method according to any one of the above (3) to (6), and the laser assembly is performed by welding the iris portion and the cavity forming the cell portion. When performing using light, while the optical axis of the laser beam is coaxial with the rotation center of at least one of the iris portion and the cell portion, and when welding the iris portion and the cell portion from the inside, Use the light-gathering optical system required for

(8) The method of manufacturing a superconducting cavity according to the present invention is the method described in the above (7), wherein one or more reflections are introduced in order to introduce a laser beam into each of the condensing optical systems and perform welding. A mechanism is provided for opening and closing the mirror by remote control and for introducing a laser beam into the other condensing optical system.

(9) The method of manufacturing a superconducting cavity according to the present invention is the method described in the above (7) or (8), and when the cavity is welded from the inside, each of the condensing optical systems has an optical axis. Or about the central axis of the cavity, and welding is performed with the cavity fixed.

(10) The method of manufacturing a superconducting cavity according to the present invention is the method as described in (9) above, wherein each of the condensing optical systems is rotated to perform welding from the inside, and to perform non-penetration welding from the outside. If so, the cavity is rotated and welded.

(11) The method of manufacturing a superconducting cavity according to the present invention is the method according to any one of the above (7) to (10), and each of the condensing optical systems includes a light source for the iris part and a cell part. Means are provided for automatically adjusting the position of the converging point in accordance with the variation of at least one of the inner diameters, or for performing height control by automatically feeding back the variation.

(12) The method for manufacturing a superconducting cavity according to the present invention is the method according to any one of the above (7) to (11), and each of the condensing optical systems monitors a groove and forms a welding line. There is provided a detecting means for detecting the positional deviation, and a correcting means for correcting the position of the welding line based on the positional deviation detected by the detecting means.

(13) The method for manufacturing a superconducting cavity according to the present invention is the method according to any one of the above (7) to (12), wherein a spiral or a weld bead is formed near the welding line in the inner welding and the outer welding. A mechanism for increasing the lap welding width and for controlling the rotation and position of each of the condensing optical systems and the cavity is provided.

(14) The method of manufacturing a superconducting cavity according to the present invention is the method described in (13) above, and includes means for rotating the cavity and outer focusing optics provided outside the cavity in outer periphery welding. Means for driving the system parallel to the central axis of the cavity.

(15) The method of manufacturing a superconducting cavity according to the present invention is the method according to any one of the above (1) to (14), wherein the base material of the cavity is made of oxygen-free copper. An alloy of copper and nickel is used as a shim, inserted between oxygen-free copper and welded from the inside.

(16) The method for manufacturing a superconducting cavity according to the present invention is the method according to the above (15), wherein a niobium electrode is provided inside the cavity assembled by welding the oxygen-free copper, By forming a niobium plating layer on the inner surface of the cavity by performing a plating process,
Alternatively, a niobium vapor deposition layer is formed on the inner surface of the cavity by ion beam or chemical vapor deposition.

(17) The superconducting cavity of the present invention is manufactured by the manufacturing method according to any one of the above (1) to (16).

(18) A superconducting accelerator according to the present invention comprises the superconducting cavity described in (17).

As a result of taking the above-described measures, the following effects are obtained.

(1) According to the method of manufacturing a superconducting cavity of the present invention, welding defects are eliminated, and spatters and the like do not adhere to the inside of the cavity, so that an ultra-vacuum container can be easily manufactured and high-quality welding can be performed. Becomes possible.

(2) According to the method of manufacturing a superconducting cavity according to the present invention, in welding the cavity, a butt portion between a straight pipe called an iris portion and a cell portion and a butt portion between a cell portion and a short diameter portion of the cell portion are used. And, there is a butt portion of the cell portion and the long diameter portion of the cell portion called a cell portion, but in a method of manufacturing a straight pipe such as niobium, a long pipe is manufactured by rolling a plate material with a roller, and from the inside of the pipe. The jig can be used for clamping and welding so that there is no gap between the optical system of the laser beam and the butted portion.

(3) According to the method of manufacturing a superconducting cavity of the present invention, a substantially flat molten surface can be obtained on the inner surface, and good welding can be performed without generating spatter or the like.

(4) According to the method of manufacturing a superconducting cavity of the present invention, welding can be performed in a shorter time than in the case of performing both inner and outer welding.

(5) According to the method for manufacturing a superconducting cavity of the present invention, the iris portion and the cell portion can be assembled, inserted into a container, and remotely welded.

(6) According to the method of manufacturing a superconducting cavity of the present invention, after the stepped groove is fixed to some extent,
Main welding can be performed.

(7) According to the method for manufacturing a superconducting cavity of the present invention, both the iris portion and the cell portion can be efficiently welded.

(8) According to the method of manufacturing a superconducting cavity of the present invention, both the iris portion and the cell portion can be efficiently welded by remote control.

(9) According to the method of manufacturing a superconducting cavity of the present invention, welding in a circumferential direction from the inside can be performed in a stable state.

(10) According to the method for manufacturing a superconducting cavity of the present invention, each condensing optical system is rotated to perform relatively shallow welding from the inside, and then to perform non-penetrating welding from the outside, thereby performing welding from both sides. Can be reliably welded.

(11) According to the method of manufacturing a superconducting cavity of the present invention, it is possible to automatically correct the position shift of the focal point due to a change in the inner diameter of the iris portion or the cell portion.

(12) According to the method of manufacturing a superconducting cavity of the present invention, more accurate welding can be performed by automatically correcting the displacement of the welding line.

(13) According to the method of manufacturing a superconducting cavity of the present invention, the welding width is widened, so that reliable welding can be performed.

(14) According to the method of manufacturing a superconducting cavity of the present invention, by rotating the cavity, the outer periphery can be welded without rotating the outer welding optical system.

(15) According to the method of manufacturing a superconducting cavity of the present invention, welding of oxygen-free copper can be easily performed.

(16) According to the method of manufacturing a superconducting cavity of the present invention, welding of oxygen-free copper can be performed at low cost.

(17) According to the superconducting cavity of the present invention, welding defects are eliminated, a high quality and compact structure is obtained, and the superconducting cavity can be easily manufactured.

(18) According to the superconducting accelerator of the present invention,
Manufactured to high performance and high quality.

[0051]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A superconducting cavity according to an embodiment of the present invention and a method for manufacturing the same will be described below with reference to the drawings.

FIG. 1 is a view showing a configuration of a welding apparatus for a superconducting cavity (superconducting cavity) according to the present embodiment.
In FIG. 1, when welding and assembling the cavity body 1,
An iris inner welding optical system 7 and a cell inner welding optical system 6, which are light collecting optical systems suitable for the iris unit 2 and the cell unit 3, respectively, are inserted into the cavity main body 1. A rotary drive system (rotation drive unit in the cavity) 12 that rotates and a linear drive system (axis drive unit in the cavity) that moves each condensing optical system in the axial direction are provided.

In order to weld the outer periphery of the cavity body 1, a drive system (outside welding shaft drive motor) 15 for driving the outer welding optical system 8 in the height direction and the axial direction is provided. Further, a rotation motor (cavity body rotation motor) 14 for rotating the cavity body 1 is provided as a drive system.

When the iris 2 and the cell 3 are welded, these components are inserted and placed in the container 5. The container 5 is sealed, and the air inside the container 5 is discharged by the vacuum pump 9 in order to make the atmosphere in the container 5 an atmosphere of an inert gas such as an argon gas. After that, the valve 10 is closed and the valve 11 is opened to inhale the inert gas and form an atmosphere of the inert gas contained in the cavity.

FIG. 2 is a diagram showing a method of welding a straight pipe.
FIG. 2 shows a method of welding the straight pipe 16 in the axial direction.
A 3 mm thick niobium plate (or a niobium clad material) is bent by roller bending to perform welding in the axial direction. In this case, in order to perform welding from the inside of the straight pipe 16, the iris portion inside welding optical system 7 shown in FIG. 1 is inserted inside the straight pipe 16, and the linear driving system 13 in the axial direction is driven to perform welding.
Also in this case, the welding jig 17 of the iris part 2 is placed in the container 5.
And fix it with the clamp mechanism.

Thereafter, welding is performed along an axial welding line 18 of the iris portion 2 shown in FIG. 2 in an inert gas atmosphere. The laser welding conditions are an output of 2.8 kW and a welding speed of 0.5 m / min. In this case, penetration welding is performed.

FIG. 3 is a diagram showing a method of welding the iris 2 and the cell 3 inside and outside. When welding the iris part 2 and the cell part 3 of the cavity main body 1 with the welding device shown in FIG. 1, the inner and outer welding methods shown in FIG. use.

In this case, first, non-penetration welding of the iris portion welding portion 19 was performed at 2.8 kW and welding speed of 1.0 m from the inside.
/ Min laser beam to form an iris portion inner welding section 21. Further, for the cell section 3, the cell section welding section 20 is formed on the cell section welding section 20 by using the cell section inner welding optical system 6 under the same conditions as those of the iris section 2 at an output of 2.8 kW and a welding speed of 1.0 m / min. Non-penetrating welding is performed to form a cell portion inner welding section 22.

Thereafter, using the outer welding optical system 8 which is a condensing optical system dedicated to the outer periphery, an output of 2.8 kW and a welding speed of 1.
The cell part 3 and the iris part 2 are welded under the condition of 0 m / min. These cross sections are shown at 23 and 24, respectively. By using such a method, a substantially flat molten surface can be obtained on the inner surface, and good welding can be performed without spattering.

In the experiment, an output of 2.8 kW and a welding speed of 0.8 were obtained by using the both inside welding optical systems 6 and 7 shown in FIG.
Penetration welding of the iris part 2 and the cell part 3 was performed at 5 m / min. In this case, since some unevenness and spatter were generated inside, the inside of the weld was mirror-finished by flap holes and buffing. In this case, the total welding time is earlier than when performing both inside and outside welding.

FIG. 4 is a diagram showing the groove shapes of the iris 2 and the cell 3. As a groove shape of the iris part 2 and the cell part 3, as shown in FIG. 4, laser welding usually uses an I groove 25, but in this groove, it is possible to put the entire cavity in the container 5 and perform welding. It cannot be done because the assembly is lost. Therefore, it is optimal to use the spigot-shaped stepped groove 26 so as to be combined with each other.

In this experiment, since the entire cavity had to be fixed before welding, eight spot weldings were performed from outside or inside with laser light. This allows the entire cavity to be rotated. In this temporary fixing, not only spot welding but also welding at the entire inner circumference at a high speed, for example, 2.8 kW output and a welding speed of about 3 m / min, was possible.

Next, each device will be described.

FIG. 5 is a diagram showing the layout and functions of the welding optical system. First, the focusing optical system and its function will be described with reference to FIG. The laser light exit port 2 is separated from the rotation axis 36 through the optical fiber 4 so as to be slightly away from and parallel to the rotation axis 36.
7, the YAG laser light is emitted while spreading. A collimator lens 28 is provided to make the expanding laser light parallel. Next, the laser light shaped in parallel is reflected by the optical path switching mirror 29 and then reflected by the reflection mirrors 30 and 31. Then, a condenser lens 32 is incorporated so that the laser beam is finally focused on the iris welding line 38.

Further, a mechanism is provided for lowering the optical path switching mirror 29 by air pressure when welding the cell portion welding line 39. When the mirror 29 is lowered, the laser beam passes, is reflected by the reflection mirror 33 and the reflection mirror 34, is finally condensed by the condenser lens 35, and the cell unit 3 is welded. The above optical components are
The optical component built-in container 37 is configured as an integral type.
The diameter of the optical component built-in container 37 is configured to be smaller than the inner diameter of the iris portion 2.

Since the diameter of the cell section 3 is sufficiently larger than the inner diameter of the iris section 2, the location of the condenser lens is
In this state, it becomes larger than the inner diameter of the iris portion 2. Therefore, the cell-portion inner-side welding optical system 6, which is a condensing optical system for welding the cell portion 3, is folded at 90 ° and folded smaller than the diameter of the iris portion 2 when passing through the iris portion 2 by driving a motor. And

FIGS. 6A and 6B are diagrams showing a specific function and configuration of the optical component. FIG. 6A shows an iris portion, and FIG. 6B shows a cell portion. Hereinafter, a specific configuration will be described with reference to FIG. FIG.
In the welding of the iris portion 2 shown in (a), the laser beam on the optical fiber shaft 40 is collimated in a direction perpendicular to the drawing so as to be parallel to the rotation center 36 at the offset position. After passing through 28, the light is reflected by a mirror 29, reflected to the left by an upper reflecting mirror 30, reflected downward by a reflecting mirror 31, and transmitted. Thereby, the welding of the iris portion 2 at the welding line is performed by the condenser lens 32.
It becomes possible by condensing the laser light with the.

The nozzle 41 has a contact roller 42
Is provided, and a spring 43 is provided to follow the change in height. However, if the pressure is applied to the spring 43 as it is, the entire optical system will not come off from the iris unit 2, so the air cylinder gas pocket 44 is provided around the nozzle 41. When gas pressure is applied to the air cylinder gas pocket 44, the nozzle 41 contracts upward. Thereby, the nozzle 41
Can move in the axial direction without contacting the iris portion 2.

Next, the welding optical system for the groove of the cell portion 3 shown in FIG. 6B will be described. Mirror 29 described above
Has a structure that can be moved in and out by a spring and gas pressure similarly to the iris unit 2. When the gas pressure is reduced, the mirror 29 is lowered by the spring pressure, and the laser beam is transmitted and reflected by the reflection mirror 33. The cell portion 3 is transmitted to the upper left side, further reflected upward by the reflection mirror 34, and condensed by the condenser lens 35, so that the cell portion 3 is welded.

Also in this case, the contact type roller 42 is provided in the nozzle 41 to follow the height change, and before and after the welded portion,
A spring 43 and a gas pocket 44 for an air cylinder are provided, and the nozzle 41 contracts when pressure is applied. However, in the case of welding of the cell portion 3, the diameter of the cell portion 3 is large, so that the nozzle 4 cannot be removed only by this contraction.
1 does not fit within the diameter of the cell portion 3. For this reason, a mechanism is provided in which the nozzle 41 is tilted 90 ° in the direction of the rotation axis by using the gear and the worm gear by the rotation of the motor 45.
With this mechanism, the nozzle 41 will be within the diameter of the cell section 3 for the first time. In addition, 47 in FIGS. 6A and 6B is a gas supply port for expanding and contracting the nozzle.

FIG. 7 is a block diagram showing the configuration of the welding line copying apparatus. Below, the welding line copying mechanism and method are shown in FIG.
This will be described with reference to FIG. For example, as shown in FIG. 6B, a CCD camera 48 is mounted near the tip of the welding optical system of the cell unit 3 at a position parallel to the optical axis and separated by a detection position correction distance 49. Then, as shown in FIG.
The welding line image processing unit 50 grasps the groove fluctuation amount with respect to the image data obtained by the CD camera 48, and the fluctuation amount calculation unit 51 calculates the actual rotation position and groove fluctuation amount.

Further, a function of performing welding line position control by two-axis simultaneous control by motors 53 and 55 via a motor driver 52 for the rotational direction (circumferential direction) and a motor driver 54 for the axial direction, respectively. ing. This feature
It is also incorporated in the welding optical system of the iris unit 2 and can perform the same control.

With the welding line copying apparatus having the above functions, the inside of the cavity can be welded. next,
In the case of welding from the outer periphery, welding is already performed from the inside without penetrating, and the cavity body rotating motor 14
It becomes possible to rotate the cavity body 1 by
As shown in FIG. 1, control of the outer welding optical system 8 including the drive unit in the horizontal (left / right) direction is added without rotating the outer welding optical system 8. Further, regarding the vertical movement, control by the outer welding shaft motor 15 is enabled.

Here, when the cavity body 1 is rotated,
Similarly, the welding lines of the outer peripheral cell portion 3 and the iris portion 2 are also slightly displaced. For this reason, like the inner welding system, a CCD camera is provided in the outer welding optical system, the rotation angle when the cavity body is rotated and the shift amount are calculated, the shift amount is corrected, and the outer peripheral portion is welded. Perform welding with the system.

[0086] Since a system that is complicated and expensive may be obtained by providing the welding line following in this way, spiral welding is next performed as a method for reliably welding the welding line.

FIG. 8 is a diagram showing welding and assembly of cavity parts by the spiral welding method. Hereinafter, the results of welding experiments on the cell section 3 will be shown as examples. FIG. 8A is a sectional view showing a welding groove of the cell portion 3 before welding. Here, welding is performed from the inside at a power of 2.8 kW and a welding speed of 1 m / min, and as shown in the sectional view of FIG. 8B, 50% of the weld bead width is overlapped and spirally welded three times. And form multiple inner spiral weld beads.

Further, as shown in FIG. 8B, in the outer peripheral welding, the output was 2.8 kW and the welding speed was 0.8 m / m.
In, the penetration depth is slightly increased, and the overlap bead is welded six times to form multiple outer spiral weld beads 56. According to this method, welding deformation is slightly increased, but the welding width is widened, so that reliable welding can be performed.

FIG. 9 is a diagram showing a method of welding an oxygen-free copper cavity. If the material of the cavity is oxygen-free copper instead of niobium, welding with a YAG laser beam becomes even more difficult due to its low absorptivity. Therefore, in the present embodiment, as shown in FIG. 9, for example, in welding of the cell portion 3, a plate thickness 0.5 m
An experiment was performed in which a shim material 58 of m (gap direction) × 2 mm in the depth direction was inserted into the groove 26 of the welding, the shim material 58 was melted, and the heat was used to melt and weld copper.

In this experiment, nickel 70%, copper 30%
2.8 kW, welding speed 0.
The penetration welding could be sufficiently performed at 5 m / min.
After laser welding, the inner surface needs to be finished, but copper and niobium lower the material cost. Practically, after welding this oxygen-free copper, a niobium electrode is placed inside the cavity body 1 and a plating layer or a vapor deposition layer of niobium is formed on the inner surface of the cavity by plating or vapor deposition by ion beam or chemical vapor deposition. And used as a superconducting cavity.

As an application example of this embodiment, it is necessary to weld a port or the like to the cavity. In this case, since the same laser welding is possible from the inside, the optimal laser welding is used for welding the component made of the niobium material and the oxygen-free copper in the superconducting cavity. This allows
High-speed, low-strain, high-vacuum cavities can be manufactured, and as a result, the quality of the superconducting accelerator is improved.

The operation of the present embodiment will be described below.

(1) When welding the cavity, it is necessary to form an inert gas atmosphere both inside and outside the cavity. In this case, both the iris portion 2 and the cell portion 3 are assembled by laser welding with a groove having a thickness of several mm, which is formed by pressing or sheet metal working and mechanical working, so that a gap always occurs. For this reason, it is necessary to form an inert gas atmosphere on both the front side and the back side of the cavity.

In this case, since the cavity is relatively large, both the cavity and the optical parts for welding are set in a container, and argon gas is supplied from the outside while the air in the container is pulled by a vacuum pump. Then, after confirming the oxygen concentration and performing sufficient replacement, control is performed to simultaneously flow argon gas from the nozzle portion of the welding optical system and also flow argon gas into the outer container.

(2) The iris portion 2 is formed by bending a plate material into a cylindrical shape by bending first, and then welding the ridge portion of the cylinder from the inside using the same optical system as the circumferential welding optical system. Perform After that, the end face is machined and the groove at the circumferential portion is machined. Also in this case, the welding is performed in an inert gas atmosphere as in the circumferential welding.

(3) When welding in the circumferential and ridge directions of the iris portion 2 and in the circumferential direction of the cell portion 3 are performed from the inside, when performing machining after welding, a keyhole unique to laser welding. If welding is performed, the welding speed is fast and efficient. However, when welding from the inside, a smooth weld bead surface can be obtained by welding only the surface layer, so that post-machining machining is not required.

(4) Even in the case of assembling by penetration welding, if welding is performed from the outside, the bead on the inside rises,
Alternatively, since much internal machining by sputtering is required, penetration welding from the inside is appropriate.

(5) Since the iris unit 2 and the cell unit 3 are inserted into the container and are remotely welded, the groove is stepped to assemble each unit. Further, in order to fix the stepped groove to some extent, spot welding by laser light or continuous temporary welding at a welding depth of 1.5 mm or less is performed, and then main welding is performed.

(6) Since the welding is performed in the circumferential direction from the inside, the center of rotation of the optical system is made substantially coincident with the center of rotation of the cavity. Further, since the diameters of the iris 2 and the cell 3 are greatly different, a condensing optical system suitable for each turning radius is configured.

(7) When the focusing optical system is once set in the cavity, it is necessary to switch the laser beam to each of the welding optical systems of the iris 2 and the cell 3 for transmission. For this reason, the reflection mirror built in one of the condensing optical systems is opened and closed by remote control.

(8) When welding from the inside, since the respective components are not integrated, the welding cannot be performed by rotating the cavity body. For this reason, welding is performed by rotating the optical system.

(9) Since the welding surface in the cavity is as flat as possible and requires no post-processing and welding without unevenness in the welding bead, a relatively shallow welding is performed from the inside, and after this welding, the outside of the cavity is removed. The strength of the cavity is increased by performing welding from the outside of the cavity by another condensing optical system provided in the cavity.

(10) Although the inside of the cavity is machined, the focal point of the laser beam needs to be corrected because the center of rotation is slightly shifted or the diameter (inner diameter) is slightly different. For this reason, the structure of the optical system is considered in consideration of contact-type scanning, and for non-contact scanning, CC
The height of the focal point detected by a D camera or a height sensor is fed back and controlled.

(11) Even when the optical system is rotated about the center of rotation, the plane perpendicular to the rotation axis is not always perpendicular. That is, the welding line may be shifted. In order to correct this, the position of the welding line is corrected by monitoring the groove with a CCD camera or the like, detecting the displacement of the welding line, and simultaneously controlling the two axes in the rotation direction and the axial direction.

(12) Since the welding bead of laser welding is narrow, in order to sufficiently satisfy the condition, the welding bead is spirally overlapped several times near the welding line and welded. For this reason, when welding the inside, two-axis simultaneous control of the rotation control mechanism for the rotation axis of each condensing optical system and the position control mechanism for the direction parallel to the drive axis of each condensing optical system in a direction perpendicular to the rotation axis Control is performed by a mechanism. Further, when welding is performed from outside the cavity, two axes are simultaneously controlled by a mechanism for controlling the rotation of the cavity body and a position control mechanism for linearly moving the condensing optical system provided outside in a direction parallel to the center axis of the cavity. Control.

(13) When the base material of the cavity is made of oxygen-free copper and niobium is formed by post-processing such as plating on the inside of the cavity, a method of welding oxygen-free copper is required. In this case, it is difficult to weld oxygen-free copper with laser light. For this reason, for welding between oxygen-free coppers, insert a shim made of an alloy of copper and nickel into the groove,
The shim is melted and oxygen-free copper is welded from the inside.

(14) The superconducting accelerator needs a cavity welded by the above method. Further, since the superconducting accelerator is composed of other ports and copper, the above method is a technique necessary for assembling the superconducting accelerator.

The present invention is not limited to the above-described embodiment, and can be modified as needed without departing from the scope of the invention.

[0098]

According to the present invention, a high-quality superconducting cavity having no welding defects, a method for manufacturing the superconducting cavity, and a superconducting accelerator constituted by the superconducting cavity can be provided.

[Brief description of the drawings]

FIG. 1 is a diagram showing a configuration of a welding device for a superconducting cavity according to an embodiment of the present invention.

FIG. 2 is a view showing a method for welding a straight pipe according to an embodiment of the present invention.

FIG. 3 is a view showing a method for welding the inside and outside of the iris portion and the cell portion according to the embodiment of the present invention.

FIG. 4 is a diagram showing a groove shape of an iris portion and a cell portion according to the embodiment of the present invention.

FIG. 5 is a diagram showing a layout and functions of a welding optical system according to the embodiment of the present invention.

FIG. 6 is a view showing a specific function and configuration of the optical component according to the embodiment of the present invention.

FIG. 7 is a block diagram showing a configuration of a welding line copying apparatus according to an embodiment of the present invention.

FIG. 8 is a diagram showing welding and assembly of cavity parts by a spiral welding method according to the embodiment of the present invention.

FIG. 9 is a view showing a method of welding the oxygen-free copper cavity according to the embodiment of the present invention.

FIG. 10 is a diagram showing a state of high energy beam welding according to a conventional example.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Cavity main body 2 ... Iris part 3 ... Cell part 4 ... Optical fiber 5 ... Container 6 ... Cell part inside welding optical system 7 ... Iris part inside welding optical system 8 ... Outside welding optical system 9 ... Vacuum pump 10 ... Valve 11 ... Not Active gas suction valve 12 ... Cavity optical system rotation drive unit 13 ... Cavity optical system shaft drive unit 14 ... Cavity body rotation motor 15 ... Outside welding shaft drive motor 16 ... Straight pipe 17 ... Welding jig 18 ... Welding line DESCRIPTION OF SYMBOLS 19 ... Iris part welding part 20 ... Cell part welding part 21 ... Iris part inside welding section 22 ... Cell part inside welding section 23 ... Iris part outside welding section 24 ... Cell part outside welding section 25 ... I groove 26 ... Stepped groove 27 Laser emission exit 28 Collimator lens 29 Optical path switching mirror 30 Reflection mirror 31 Reflection mirror 32 Iris part melting Contact condenser lens 33 ... Reflection mirror 34 ... Reflection mirror 35 ... Cell part welding condenser lens 36 ... Rotating axis 37 ... Optical component built-in container 38 ... Iris part welding line 39 ... Cell part welding line 40 ... Fiber shaft 41 ... Nozzle 42 ... Contact roller 43 ... Spring 44 ... Gas pocket for air cylinder 45 ... Motor 46 ... Gear 47 ... Gas supply port 48 ... CCD camera 49 ... Detection position correction distance 50 ... Welding line image processing unit 51 ... Fluctuation amount calculation unit 52 ... Circumferential motor driver 53 ... Circumferential motor 54 ... Axial motor driver 55 ... Axial motor 56 ... Outer spiral weld bead cross section 57 ... Inner spiral weld bead cross section 58 ... Shim material 59 ... Normal height Energy beam welding cross-sectional shape 60: Cross-sectional welding shape when gap is large 61: Burn-out Undercut welding cross section due

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) B23K 26/12 B23K 26/12 33/00 33/00 Z (72) Inventor Katsunori Shiihara Tsurumi, Yokohama City, Kanagawa Prefecture 2-4, Suehirocho, Ward Toshiba Keihin Works Co., Ltd. (72) Inventor Yoshinobu Makino 2-4, Suehirocho, Tsurumi-ku, Yokohama-shi, Kanagawa Prefecture F-term in Toshiba Keihin Works Co., Ltd. 2G085 BA05 CA02 CA12 CA26 CA26 EA01 EA02 EA04 4E068 AA02 AA04 BA01 BA03 BE02 BE03 BG01 CA10 CA11 CA14 CC02 CC06 CD04 CD08 CD16 CE01 CE08 CF01 CJ01 DA00 DA06 DA15 DB02

Claims (18)

[Claims] 1. When welding is performed using laser light, the entire cavity is set in a container, and the optical head for condensing the laser light is inserted into the cavity and the inside of the cavity and the inside of the container are inserted. And suctioning an inert gas, and then welding with the laser beam in a state where the atmosphere inside and outside the cavity is made an inert gas atmosphere of high purity and the same pressure. Manufacturing method of superconducting cavity. 2. The method for manufacturing a superconducting cavity according to claim 1, wherein a straight pipe is manufactured by bending a plate material, and fixed by a jig from inside the straight pipe and welded. 3. The method according to claim 1, wherein the welding of the straight pipe and the welding of the iris portion and the cell portion are performed by non-penetration welding using laser light from the inside, and also performed by non-penetration welding using laser light from the outside. A method for manufacturing a superconducting cavity according to claim 2. 4. The method for manufacturing a superconducting cavity according to claim 2, wherein the welding of the straight pipe and the welding of the iris portion and the cell portion are performed by penetration welding using a laser beam from the inside. 5. The method for manufacturing a superconducting cavity according to claim 3, wherein a groove of welding between the iris portion and the cell portion has a stepped shape. 6. The welding of the iris portion and the cell portion is performed by temporarily fixing spot welding by a laser beam or by temporarily fixing welding at a welding depth of 1.5 mm or less. A method for manufacturing a superconducting cavity according to any one of claims 3 to 5, wherein: 7. An optical axis of the laser beam is coaxial with a rotation center of at least one of the iris portion and the cell portion when performing welding assembly of the iris portion and the cavity forming the cell portion using laser light. The superconducting cavity according to any one of claims 3 to 6, wherein when the iris portion and the cell portion are welded from the inside, a condensing optical system necessary for each is used. Method. 8. A mechanism capable of remotely opening and closing one or more reflecting mirrors and introducing laser light to the other condensing optical system in order to introduce laser light to each of said condensing optical systems and perform welding. The method for manufacturing a superconducting cavity according to claim 7, comprising: 9. When welding the cavity from the inside,
9. The method according to claim 7, wherein each of the condensing optical systems rotates about an optical axis or about a central axis of the cavity, and welding is performed with the cavity fixed.
3. The method for manufacturing a superconducting cavity according to claim 1. 10. The method according to claim 9, wherein the welding is performed by rotating each of the condensing optical systems, and when performing non-penetration welding from outside, the cavity is rotated to perform welding. Of manufacturing a superconducting cavity. 11. Each of the converging optical systems automatically adjusts the position of the converging point in accordance with the amount of change in the inner diameter of at least one of the iris portion and the cell portion, or automatically adjusts the amount of change. The method for manufacturing a superconducting cavity according to any one of claims 7 to 10, further comprising: means for performing height control by feedback in a dynamic manner. 12. Each of the condensing optical systems monitors a groove and detects a displacement of a welding line, and corrects the position of the welding line based on the displacement detected by the detecting means. The method of manufacturing a superconducting cavity according to any one of claims 7 to 11, further comprising: a correcting unit. 13. A mechanism for superposing a spiral or welding bead near the welding line to increase the welding width in the inner welding and the outer welding, and for controlling the rotation and position of each of the condensing optical systems and the cavities. The method for manufacturing a superconducting cavity according to any one of claims 7 to 12, comprising: 14. An outer peripheral welding device comprising: means for rotating said cavity; and means for driving a converging optical system provided outside said cavity in parallel with a central axis of said cavity. A method for manufacturing a superconducting cavity according to claim 13. 15. When the base material of the cavity is made of oxygen-free copper, an alloy material of copper and nickel is used as a shim, inserted between the oxygen-free copper and welded from the inside. The method for manufacturing a superconducting cavity according to any one of claims 1 to 14, wherein 16. A niobium electrode is provided inside the cavity assembled by welding the oxygen-free copper, and a plating process is performed to form a niobium plating layer on the inner surface of the cavity, or The method according to claim 15, wherein a niobium deposition layer is formed on an inner surface of the cavity by a beam or a chemical vapor deposition method. 17. A superconducting cavity manufactured by the manufacturing method according to claim 1. 18. A superconducting accelerator comprising the superconducting cavity according to claim 17.