JPH04218300A - Superconductive acceleration tube and manufacture thereof - Google Patents

Abstract

PURPOSE:To provide a superconductive acceleration tube which can be manufactured in a short manufacturing time, with a simple jig, at a low cost, and with an easy weld work, and provide manufacturing thereof for the acceleration tube having equivalent or exceeding characteristics to those obtained by electron beam weld in manufacturing the superconductive acceleration tube. CONSTITUTION:A superconductive acceleration tube 10 is composed of a plural component parts 11, 12, 13 comprising superconductive material welded with each other at peripheral parts. The superconductive acceleration tube 10 is welded by a laser beam at each peripheral part. The component parts 11, 12, 13 having the peripheral parts to be put to each other and comprising the superconductive material are laser welded by a laser beam radiated to the peripheral parts.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a superconducting high-frequency accelerator tube using Nb or the like for a charged particle accelerator, and a method for manufacturing the same.

0002

[Prior Art] The principle of an accelerator is to adjust the phase velocity of a traveling wave that has an electric field component in the traveling direction of the charged particles so that the charged particles are always in the acceleration phase and are affected by the accelerating electric field. This accelerates charged particles. Among such accelerators, in an accelerator that uses a high-frequency electric field, an accelerating tube is used as a means for generating the high-frequency electric field.

[0003] In order to obtain a high accelerating electric field with lower power, a superconducting accelerator tube made of a superconductor is used, and the material used is niobium (Nb) or the like. Also,
Since the current excited by the high-frequency electric field flows near the inner surface of the accelerator tube, charged particles do not jump out of the tube near the peripheral edge of the inner surface where the component parts are joined, making the flow of charged particles smooth. Improving electrical characteristics is important. Furthermore, superconductors such as Nb must be processed without being oxidized, since their superconducting properties deteriorate due to oxidation.

[0004] As a method for manufacturing a superconducting accelerator tube, for example, a superconducting material such as Nb is cut or press-molded to form a flange 1, a cell coupling part 2, as shown in FIGS.
Components such as a half-split cell 3 having a small diameter portion 3a and a large diameter portion 3b are manufactured, and these are abutted against each other at their peripheral ends and welded together to form an acceleration tube. Here, as shown in FIG. 25, an acceleration tube with one cell is used as a single cell acceleration tube 4, and as shown in FIG. 26, an acceleration tube with a plurality of cells connected as a multi-cell acceleration tube 5.
It is called.

[0005] TIG welding, electron beam welding, etc. are used to weld the acceleration tubes 4 and 5, but electron beam welding is currently mainly used because it allows the production of acceleration tubes with good electrical characteristics. ing.

[0006]

However, the conventional method of manufacturing an accelerating tube in which component parts are joined together by electron beam welding has the following problems. That is,
In electron beam welding, the components of the accelerator tube are joined together in a vacuum vessel, but from the standpoint of allowing the electron beam to travel straight without scattering and to prevent oxidation of superconductors such as Nb, the degree of vacuum is 1.
It is necessary to perform welding under a high degree of vacuum of 0-6 torr or less.

Furthermore, during welding, the acceleration tube is held at both ends with jigs inside the vacuum container, so the degree of vacuum inside the acceleration tube must be made as high as the outside vacuum inside the vacuum container. Therefore, it was necessary to provide the jig with gas venting measures such as communication holes to increase the conductance so that the degree of vacuum inside and outside the accelerating tube is equal. For this reason, the jig becomes expensive, and it takes time to evacuate the vacuum container.
There are problems in that the pre-welding process takes a lot of time, the equipment such as vacuum vessels and jigs is large-scale, the manufacturing cost of the superconducting accelerator tube is high, and the welding work is extremely complicated.

[0008] The present invention has been made in view of the above points, and it is possible to manufacture an accelerating tube having characteristics equal to or better than electron beam welding at a low cost using a short manufacturing time and a simple jig. It is an object of the present invention to provide a superconducting accelerator tube and a method for manufacturing the same which are easy to weld.

[0009]

[Means and Effects for Solving the Problems] In order to achieve the above object, the present invention provides a superconducting accelerator tube formed by welding the circumferential ends of a plurality of components made of superconducting material to each other. In this case, each of the peripheral ends is welded by a laser beam. The second aspect of the present invention also relates to the production of a superconducting accelerator tube having circumferential ends that abut against each other and in which a plurality of components made of superconducting material are laser welded to each other using a laser beam irradiated to the circumferential ends. This is a method.

[0010] In the superconducting accelerator tube of the present invention, only the inner surface of each circumferential end portion is laser welded, and the welding depth is one-half or less of the thickness of the superconducting material. Here, "only the inner surface is laser welded" means that when the peripheral end is welded from the inside of the acceleration tube, only the surface portion of the manufactured acceleration tube is melted and welded. When welding from the outside,
This means that the molten part reaches the inner surface of the accelerated tube to be manufactured, and the bead on the inner surface is smoothly welded without becoming wavy.

[0011] When the welding depth is deeper than one-half of the thickness of the superconducting material, the dimensional accuracy of the manufactured superconducting accelerator tube deteriorates due to shrinkage of the welded portion. Also, the depth of welding is 15
The reason why the diameter was set to 0 μm or more was that 50 μm was applied to the welded part in the subsequent polishing process.
This takes into consideration surface polishing of approximately 100 μm. Furthermore, the reason why the outside of the accelerating tube is fixed using a jig is to prevent the manufactured superconducting accelerating tube from deforming due to external forces such as vibrations.

[0012] When the thickness of the superconducting material is less than 0.1 mm, the strength becomes weak and the thickness is too thin to perform good laser welding. On the other hand, the thickness of the superconducting material is 1 m.
If it exceeds m, the thermal conductivity decreases and the cooling efficiency of the superconducting accelerator tube decreases, which is not preferable. In the method for manufacturing a superconducting accelerator tube of the present invention, by irradiating the peripheral ends of the butted components with a laser beam and laser welding the inner surfaces, the surface of the superconducting accelerator tube is smoothed to a depth of about 150 to 300 μm. Can be welded and has good electrical characteristics (Q
A high-precision accelerator tube with a large value (Q quality factor) and little welding distortion can be obtained.

In addition, when welding work is performed in an inert gas atmosphere, there is no need to create a high vacuum atmosphere as in electron beam welding, and the heat generated in the welding area can be efficiently removed, so welding can be performed with thin walls. This method is particularly preferred in the case of an accelerator tube, but a simple vacuum may be used as long as oxidation of the superconducting material can be prevented. On the other hand, if we spot-weld multiple points on the circumferential ends of the components butted against each other to temporarily attach them, and then weld the entire circumference, the components can be properly positioned with respect to each other, and the superconducting The dimensional accuracy of the accelerator tube is improved.

Furthermore, when welding the entire circumferential edge, the area to be welded is divided into two or more areas, and after welding of one area is completed, a predetermined cooling time is allowed before welding of the next area is started. Lowering the overall temperature of the welded components allows for rapid cooling due to the temperature difference between the weld and its surroundings, which prevents excessive oxidation of the superconducting material. In addition, by avoiding excessive temperature rise and shortening the time in the high temperature state by rapid cooling, sagging and burn-through of the welded portion can be prevented.

[0015]

[Embodiment 1] Hereinafter, a first embodiment of the superconducting accelerator tube and its manufacturing method of the present invention will be described in detail with reference to FIGS. 1 to 9. The superconducting accelerating tube 10, like the multi-cell accelerating tube shown in FIG.
2 and the flange 13 are formed into a tubular shape by laser welding only the surfaces of the peripheral end portions to each other.

The half cell 11 has a thickness of 0.5 mm and an outer diameter of 9
It is a dish-shaped member with an open peripheral end of cm, and a small diameter part 11a is formed at one end of the peripheral end, and a large diameter part 11b is formed at the other end. The connecting member 12 connects the half cells 11, 11 to each small diameter portion 11a.
It is a ring-shaped member that connects with
Stepped portions 12a, 12a are formed which abut the tips of a.

The flange 13 is a member disposed at both ends of the superconducting acceleration tube 10, and has a small diameter portion 1 of the half-split cell 11 at one end.
It has a tube portion 13a to which the tube portion 1a is welded, and a flange portion 13b extending radially from the other end of the tube portion 13a. In the present invention, the superconducting accelerator tube 10 is configured as described above, and is manufactured using the components 11 to 13 as described below.

First, as shown in FIG. 3, a superconducting accelerator tube 1
An optical system 20 for laser welding 0 and a chamber 30 are arranged as shown in the figure when viewed from above. In the figure, 21 is YAG
A laser generator, 22 a probe light source (He-Ne visible light laser light source) used for positioning the welding part, 23
is a condensing mirror that condenses the YAG laser beam (focal length f=
4.5 cm), 24 is a pipe for flowing inert gas to cool the condensing mirror 23, 25 is a bend mirror that defines the optical path 26 of the laser beam, 31 is an arrow pointing inside the chamber 30,
A movable table 32 is movable in the horizontal direction indicated by Y and is used for welding work with the accelerator tube 10 installed; 32 is a movable table 31;
The rotating device 33 installed above is a window that is provided in a chamber 30 filled with inert gas and that transmits laser light.

Here, the optical system 20 connects the optical axis A of the YAG laser beam that exits the YAG laser generator 21, is refracted by the condensing mirror 23, and reaches the probe light source 22, and the visible light emitted from the probe light source 22. is set so that the optical axis B of Next, as shown in FIG.
11 are laser welded at each small diameter portion 11a via a connecting member 12 to produce a plurality of cell parts. In addition, superconducting accelerator tube 1
The half cell 11 arranged at both ends of the cell 0 has a small diameter portion 11a.
The pipe portion 13a was welded to the flange 13 (not shown).

[0020] Next, the plurality of cell parts manufactured in this manner are attached to the large diameter part 11b, which is the peripheral end of each half cell 11.
a ring-shaped jig 4 as shown in Fig. 5.
Tighten and fix at 0. Here, the jig 40 consists of a pair of symmetrical fastening jigs 41 and 42, and is shown in FIGS.
As shown in FIG. 5, two semicircular notches 41a and 42a are provided on the outside, and small holes 41b and 42b penetrating from the outside to the inside are formed, and as shown in FIG. They are connected to each other by pins 43 at the parts.

In this way, the jig 40 for attaching two cell parts
After fixing and connecting them into a tubular shape to form a tubular body T, as shown in FIG.
The connection pipe 4 is attached to each notch 41a, 42a of the
4 was integrated by tightening it with a fastening band 45. After that, a circular flange 46 having a threaded hole in the center is fixed to both ends of the four connecting pipes 44, and each cylindrical pressing member has a threaded portion 47a formed on its outer periphery to be threaded into the threaded hole of the circular flange 46. 47 was screwed into the screw hole, and the tubular body T was tightened from both sides.

At this time, with respect to each pressing member 47, the tightening force of the tubular body T was adjusted by adjusting the amount of screwing of the circular flange 46 into the screw hole. Each pressing member 47 also has an opening (
A Nb-made backing plate 48 having a metal oxide (not shown) was attached to take care not to impair the superconducting properties of the superconducting accelerator tube 10 manufactured by laser welding.

Next, as shown in FIG. 1, the tubular body T was set in the chamber 30, each circular flange 46 was attached to the rotating device 32, and the moving table 31 was positioned as follows. First, the table 31 was moved in the direction of the arrow X in the figure, and the small holes 41b and 42b of the fastening jigs 41 and 42 were positioned on the optical axis B using the probe light source 22.

After that, the table 31 moves in the direction of arrow Y.
was moved to position the welding portion on the focal point of the condensing mirror 23. Here, the welded portion refers to the surfaces of the large diameter portions 11b, 11b which are the peripheral ends of the half cells 11, 11 butted against each other, and the same applies to each of the following examples. In this embodiment, the outer diameter of the half-split cell 11 is 9 cm, and the condensing mirror 2 is
The focal length of No. 3 was set to 4.5 cm. Therefore, if the condensing mirror 23 is placed at the center of the half-split cell 11, the YAG
The YAG laser beam output from the laser generator 21 and condensed by the condensing mirror 23 converges on the inner surface of the large diameter portion 11b of each half cell 11, which is the welding portion.

After positioning the movable table 31 in this manner, the chamber 30 is filled with inert gas from the pipe 24, and each circular flange 4 is rotated by the rotating devices 32, 32.
6, the entire tubular body T was rotated, and the inner surface of the welded portion was welded. At this time, the leaked YA for processing
In order to prevent the chamber 30 from being destroyed by the G laser beam, the beam absorber 27 was moved as shown by the arrow in the figure and placed on the optical path.

After welding one round along the welded part in this way, the movable table 31 is moved one pitch (=3.
5 cm), and welded the welded portions of adjacent half cells 11,11. Hereafter, repeat the same operation and half-split cell 1
1. A superconducting accelerator tube 10 was manufactured in which the components of the connecting member 12 and the flange 13 were laser welded to each other at the welding part.

The welding conditions in this example were as follows. The YAG laser wavelength is 1.6 μm, the average output is 200 W, and the pulse width is 10 msec. , the repetition frequency was 10 Hz, and the peak power was 2.0 KW. Various measurements were performed on the superconducting accelerator tube 10 manufactured as described above. As a result, since the YAG laser beam was irradiated only on the peripheral edge surface, only the surface of each component was laser welded, and the welding depth at the welded part was 200 μm after internal polishing (50 μm).

In addition, the dimensional accuracy of the manufactured accelerator tube was approximately 100 μm in the length before and after welding per unit cell in the case of conventional electron beam welding, whereas the dimensional accuracy of the laser welding in this example was approximately 100 μm. It was improved to 10 μm or less. Here, the acceleration tube 10 manufactured according to this example may be used while being fixed with the jig 40 even after welding, and in this way, the mechanical strength of the acceleration tube 10 can be further increased. It is.

[0029]

[Example 2] Next, as a superconducting accelerator tube, a resonance frequency of 28
56MHz, cell length 3.5cm, cell thickness 0.5mm
A second embodiment of the method of the present invention for manufacturing a single-cell accelerator tube by pulse-radiating a YAG laser will be described with reference to FIGS. 10 to 12. Here, in each of the following examples, the components of the superconducting accelerator tube are the half cell 11 made of Nb, the connecting member 12, and the flange 13, as in Example 1, so the same reference numerals will be used in the following description. Explain using.

In this embodiment, using a welding apparatus 50 shown in FIG.
Weld by irradiating G laser light. The welding device 50 is installed on a moving table 51 and has a container 52 with an open top.
Inside, a workbench 53 on which the above components are placed and welded is arranged at the bottom, and a supply pipe 54 for supplying inert gas is installed, and is located approximately in the middle of the container 52 in the depth direction. A blowout nozzle 55 is arranged above the workbench 53.

The movable table 51 is a table that is movable in three axes, horizontally (back and forth, left and right) and up and down.
The component parts installed on the workbench 53 are moved in three axial directions, and YAG laser light is irradiated onto the surfaces of the peripheral end portions that are abutted against each other. The workbench 53 is made of a material with high thermal conductivity, such as a copper plate, in order to promote temperature reduction due to the heat dissipation effect of the welded components, and in FIG.
1 and a flange 13 are installed with their peripheral ends butted against each other. However, when welding the half cell 11 and the connecting member 12, a predetermined jig (not shown) is installed on the workbench 53.

[0032] The supply pipe 54 is filled with an inert gas, for example,
Argon gas is blown into the container 52 near the workbench 53 to fill the container 52 (downward displacement) at a rate of 20 liters/min during welding and until the temperature of the welded components has sufficiently decreased. Continuously supply at the above flow rate. The blowing nozzle 55 has the components 11 and 13 abutted against each other.
When irradiating the peripheral end surface with a beam of YAG laser light, an inert gas such as argon gas is blown out to the welded part.

In the welding method of this embodiment,
First, place the halved cell 11 on the workbench 53 inside the container 52 by butting the small diameter portion 11a and the end of the tube portion 13a together as shown in the figure.
and flange 13 were set, and argon gas was flowed into the container 52 from the supply pipe 54. Next, the moving table 5
1, and irradiated the welded part of the circumferential end surface of the half cell 11 and flange 13, which were butted against each other, with a YAG laser beam, and argon gas was blown out from the blowing nozzle 55 toward the welded part at four locations. It was spot welded and temporarily attached. At this time, the irradiation conditions of the YAG laser beam during spot welding were such that the pulse width was set to 70% of the laser beam used for welding over the entire circumference of the welded portion, which will be described below.

Next, the movable table 51 was moved along the welding area in three axial directions in a circumferential manner, and welding was performed over the entire circumference of the welding area using the peak power of the YAG laser beam. At this time, for example, when the circumferential length to be welded is relatively short, such as when the diameter of the small diameter portion 11a of the half-split cell 11 is 18 mm (peripheral length≒57 mm), the unit of heat that enters the welded portion by laser light irradiation is If the allowable heat capacity per circumference was large, welding was performed at one time. On the other hand, the diameter of the small diameter portion 11a is 38 mm.
(Perimeter ≒ 120 mm), when the circumference to be welded is relatively long and the allowable heat capacity per unit circumference is small, the structure of the half cell 11, connecting member 12, flange 13, etc. to be welded is Considering the effect of temperature rise on the parts, the weld zone was divided into multiple areas and welded.

At this time, for example, if the circumferential length to be welded is long, eight welds are made along the welded portion of the circumferential ends of the half cell 11 and the flange 13 where they butt together, as shown in FIG. It was divided into regions a to h. After welding area a, we wait for 2 minutes of cooling time to lower the overall temperature, and then weld area e, which is located on the opposite side to the center of area a.
After welding, weld the area c → area g → area b → area f → area h → area d in the same manner while taking cooling time,
All areas were welded.

Next, the cell parts consisting of the half cells 11 and the flanges 13 thus welded are welded together by abutting the large diameter portions 11b of each half cell 11 against each other. For this welding, a welding device 60 shown in FIG. 12 is used. The welding device 60 includes rotating means 62 and 63 on a base 61.
are arranged facing each other at a predetermined interval, and the rotating means 62, 6
A blowout nozzle 64 is arranged between the three.

At least one of the rotating means 62 and 63 is movable toward and away from the other rotating means on the base 61, and includes a rotating member 62a, which is rotated by a driving means such as a motor.
63a. In addition, the rotating member 62a is made of aluminum in consideration of rapid temperature drop due to heat dissipation of the cell parts consisting of the welded half cell 11 and flange 13, and is configured such that the argon supply pipe 65 can be freely inserted therethrough. The supply pipe 65 is inserted into the cell parts when welding them together, and supplies an inert gas such as argon gas at a rate of 20 liters/min. Supply at a flow rate of

In the method of manufacturing a superconducting accelerator tube of this embodiment, the welding device 60 is used to butt the cell parts together at the large diameter portions 11b, 11b of the halved cell 11, and the butted large diameter portions A fastening band 66 is attached to the outer periphery of the large diameter portions 11b, 11b, and assembled so that the displacement between the large diameter portions 11b, 11b that are butted together is reduced, as shown in FIG.

Here, the fastening band 66 is provided with three elongated holes 66a extending in the circumferential direction and each having a width of 5 mm and a length of 4 cm. After that, as shown in the figure, an aluminum jig 67 is placed between the flange 13 of one of the cell parts and the rotating member 63a, and the jig 67 made of aluminum is placed in consideration of the heat dissipation effect like the rotating member 62a, and the jig 67 is butted against each other. The cell parts were mounted between rotation means 62 and 63, and argon gas was flowed from the supply pipe 65 into the cell parts that were butted against each other. Here, the jig 67 is provided with a gas vent hole 67a as shown in the figure in order to prevent an increase in internal pressure due to the supply of argon gas.

Next, the half cells 11 are butted against each other.
, 11 was irradiated with YAG laser light while blowing out argon gas from the blow-off nozzle 64, and spot welded at three locations corresponding to each of the elongated holes 64a of the fastening band 64 to temporarily fix them. At this time, the irradiation conditions for YAG laser light in spot welding are such that the intensity is 1 of the peak power.
/2 to 1/3, and the pulse width was set to 30 to 80% of the width when welding over the entire circumference.

Next, the fastening band 64 is removed from the outer periphery of the large diameter portions 11b, 11b of the cell components that are butted against each other, and the large diameter portions 11b, 11b of the cell components that are butted against each other are removed.
The rotating means 62,
63, while rotating the cell component, spot welding was performed at a plurality of locations along the welded portions of the surfaces of the butted large diameter portions 11b, 11b.

Thereafter, welding was performed over the entire circumference using the peak power of YAG laser light. At this time, the entire circumference of the welded part was divided into 16 areas, and welding was performed in the same manner as described above after a cooling period of 1 minute. In the single-cell accelerator tube manufactured by the above method, it is heated in an atmosphere sprayed with argon gas so that the overall temperature of the components does not exceed 100°C.
After dividing the weld into several areas and welding a few centimeters, pulse welding was performed with a cooling period, so the weld was rapidly cooled and almost no weld distortion due to heat was observed. The electrical properties were also improved compared to electron beam welding performed in a vacuum of 10-6 torr.

Furthermore, when a single cell accelerator tube having the same structure as that of this example is manufactured by conventional electron beam welding, the
While it took 5 hours, the method of this example took 40 to 6 hours.
It could be manufactured in 0 minutes, and the manufacturing time could be dramatically reduced.

[0044]

[Example 3] Next, as a superconducting accelerator tube, a resonance frequency of 28
56MHz, 2/3π mode multi-cell accelerator tube, YAG
A third embodiment of the method of the present invention for manufacturing by emitting laser pulses will be described with reference to FIGS. 13 to 15. First of all,
In the same manner as in Example 1, as shown in FIGS. 13 and 14, the half cell 11, the flange 13, and the half cells 11, 11
A plurality of cell parts were made by welding the peripheral ends of the cell parts to each other via the connecting member 12.

Next, after assembling the plurality of cell parts by abutting each other and fastening them with fastening bands 66, as shown in FIG.
I installed it in between. Next, in the same manner as in Example 2, after spot welding the long holes 66a of each fastening band 66 to temporarily fasten each of the cell parts, each fastening band 66 was removed.
Argon gas was supplied from the supply pipe 65 into the cell parts that were butted against each other.

Then, while rotating the cell parts together by the rotating means 62 and 63, the abutted large diameter portion 1
Welding was carried out along the entire circumference along the welded portions of the surfaces of 1b and 11b using the peak power of the YAG laser beam. Here, YAG
In order to converge the laser beam, the focal length f=
A 120 mm condensing lens was used, and the welding conditions using laser light were as follows.

[0047]
Welding conditions using laser light
Half cell and flange
Half cell mutually parallel beam diameter (mm)
30
30 peak power (KW)
3.25 (1.25)*1
3.08 (1.25) *1 Pulse width (m sec.)
10
10 frequencies (Hz)
12
12 Traveling speed (mm/min.) *2
180
180 nozzle diameter (mm)
6
6 Argon gas flow rate
30
40 (liter/min
．． )
Distance between component parts (mm)
5
3*1 The value in parentheses is the intensity of laser light in spot welding *2 Traveling speed (mm/min.) The phrase refers to the traveling speed of laser light along the surface of the weld.

[0048] In the multi-cell accelerator tube manufactured by the above method, the welded part was divided into a plurality of regions and welded after cooling time in an atmosphere sprayed with argon gas.
Because excessive heat does not enter the weld and the weld cools quickly, there is almost no thermal distortion associated with welding, and the electrical characteristics of the weld are improved compared to electron beam welding. Ta.

Furthermore, the manufacturing time was less than 1/10 of the time required to manufacture a multi-cell accelerator tube of the same structure by electron beam welding.

[0050]

[Embodiment 4] Next, a fourth embodiment of the method of the present invention relating to manufacturing a multi-cell accelerator tube will be described based on FIGS. 16 to 18. First, in the same manner as in Example 3, a plurality of cell parts were made by welding the half cells 11, the flange 13, and the half cells 11, 11 to each other at their peripheral ends via the connecting member 12.

[0051] Thereafter, the plurality of cell parts are butted against each other and fastened with fastening bands 66 to assemble them.
As shown in FIG. 16, rotation means 62, 6 of the welding device 60
It was installed for 3 years. Next, argon gas was supplied from a jig 68 inserted into the supply pipe 65 into the cell parts that were butted against each other, and YAG laser light was guided into the cell parts through the optical fiber 70.

In this way, each cell component is irradiated with a laser beam from the inside and temporarily attached by spot welding at the welded portion on the inner surface of the large diameter portion 11b of the half-split cell 11, and then each fastening band 66 is removed. As in Example 3, the welded area was divided into a plurality of areas, cooled for 1 minute, and then welded over the entire circumference of the welded area using a laser beam with a peak power of 7 kW. Here, as shown in FIGS. 17 and 18, the jig 68 is a pipe-shaped member that guides the tip of the optical fiber 70 inserted therein to the welding part while supporting it with support members 68a, 68a. 6
Control plates 68b, 68b for forcibly spraying the argon gas sent inside to the welding part are provided at the tip of the welding part 8. In addition to the argon gas blown from the supply pipe jig 68, the welded area is made into an inert atmosphere by argon gas blown from an externally provided blow-off nozzle 69, and is forcibly cooled.

Therefore, in this embodiment, by using the optical fiber 70, compared to the case where the laser beam is focused by a condensing lens or a condensing mirror and irradiated to the welding part,
The optical system became smaller, making it possible to manufacture smaller accelerator tubes. In addition, since welding is performed from the inside, the bead on the inner surface of the welded part is finished neatly without becoming wavy, and the dimensional accuracy of the welded part is also good, and the manufactured accelerator tube has improved electrical properties compared to electron beam welding. Was.

[0054]

[Embodiment 5] Furthermore, FIG. 19 illustrates a fifth embodiment of the method of the present invention for manufacturing a multi-cell accelerator tube without using the connecting member 12. Similarly to the fourth embodiment, This method uses optical fibers to weld a plurality of cell parts that are butted together. Therefore, in the following explanation, only the main parts related to such welding will be explained, and the same members as in the fourth embodiment will be described with the same reference numerals in the drawings.

Cell halves 11 of cell parts to be welded together
, 11 are assembled into an accelerating tube shape by a fastening band 75 fastened to the outer periphery of the peripheral end as shown in the figure, and in this state, a YAG with a peak power of 7 KW is
Spot welding was performed by irradiating a plurality of locations with laser light from inside the large diameter portions 11b, 11b. Thereafter, YAG laser light was again irradiated from the inside through the optical fiber 70 over the entire circumference of the welded portion on the inner surface of the peripheral end portion, and the half cells 11, 11 were welded to manufacture a multi-cell accelerator tube.

At this time, each fastening band 75 that assembles a plurality of cell parts into an accelerating tube shape has a cooling water flow path 75a formed therein, and a water supply pipe 76 is connected to the flow path 75a as shown in the figure. The outside of the welded part was forcibly cooled by the supplied cooling water at a predetermined flow rate. In this way, in this embodiment, by forcibly cooling the welded part, the length that can be welded at one time can be lengthened, and the cooling time can be shortened, thereby increasing the manufacturing speed of the accelerator tube. .

[0057] It is also possible to weld a plurality of cell parts that are butted against each other from the outside. In this case,
After assembling and spot welding a plurality of cell parts using fastening bands 64 using the method shown in Examples 2 and 3, each fastening band 64 may be removed and the welded portion may be welded over the entire circumference with a laser beam.

[0058]

[Embodiment 6] Furthermore, FIGS. 20 and 21 illustrate a sixth embodiment of the method of the present invention. Similarly to Embodiment 5, the same members in the figures as in Embodiment 4 have the same reference numerals. I will explain it by attaching it. In this embodiment, the half cells 11, 11 are directly welded to each other without using the connecting member 12, and since it is difficult to position the small diameter portions 11a, 11a of the half cells 11, 11 when welding, a positioning jig is required. 80 is used for welding.

Here, the positioning jig 80 is a member made of aluminum, and as shown in FIG. 21, four protrusions 80b protruding outward in the radial direction are formed at mutually opposing positions on a cylindrical base 80a. A flow path 80c through which cooling water flows is formed in the center. In this flow path 80c,
For example, a supply pipe (not shown) for supplying cooling water is connected by a coupling such as a quick coupling.

[0060] When welding, as shown in the figure,
A positioning jig 80 is inserted between the half cells 11 and 11 inside each small diameter portion 11a, and the small diameter portions 11 are butted against each other.
There are four protrusions 8 to prevent steps from occurring on a and 11a.
The half cells 11, 11 were positioned and supported at 0b. Next, the half-split cells 11, 11 thus positioned are connected to the flow path 80c with the supply pipe, and while cooling water is flowing, argon gas is sprayed onto the welded portion from the blow-off nozzle 81 disposed nearby. Avoiding the four protrusions 80b of the jig 80, YAG laser light with a peak power of 7 KW was irradiated from the outside of the small diameter portions 11a, 11a to the welded portions using the optical fiber 70, and spot welding was performed for temporary attachment.

Next, the positioning jig 80 is removed, and while blowing argon gas from the blow-off nozzle 81, the temporarily attached half cells 11, 11 are welded from the outside of the small diameter portions 11a, 11a over the entire circumference of the welded portion. By the method of Example 3, the Y
Welding was performed by irradiating AG laser light. Next, the plurality of cell parts obtained by welding in this manner are butted against each other at the large diameter part 11b which is the peripheral end of the half cell 11, and in the same manner as in Example 3, the large diameter part 11b, A multi-cell accelerator tube was manufactured by welding the surface of 11b from the outside.

When the welded parts of the accelerator tube manufactured as described above were examined, it was found that the small diameter parts 11a and 1 were welded only on the outer surface.
No wavy weld bead was observed on the inner surface of 1a.
The welding was finished beautifully with no distortion. In the above embodiment, a YAG laser was used as a laser beam because it has a high energy absorption rate for Nb and is easy to operate out of carbon dioxide lasers and YAG lasers that are mainly used as high-output lasers.

[0063] The carbon dioxide laser has a low absorption rate for Nb, and when the output is lowered, the absorption efficiency decreases extremely, making it difficult to find suitable conditions for spot welding. Furthermore, since the absorption rate rapidly increases as the temperature rises, the temperature of the weld zone rises too much, making it difficult to obtain a desirable weld surface. However, it is also possible to use a carbon dioxide laser in the method of the present invention by shortening the pulse width and adjusting the pulse waveform to adjust the penetration depth during welding and the temperature of the weld zone.

[0064]

As is clear from the above description, according to the present invention, a superconducting accelerating tube having characteristics superior to those obtained by electron beam welding performed in a vacuum of 10-6 torr is provided, and In manufacturing, the component parts are welded using laser light, so it can be manufactured in a short time and with high precision using a simple jig.The welding work is also simple, which reduces manufacturing costs. It has excellent effects such as being able to reduce the amount of water and provide it at low cost.

[Brief explanation of the drawing]

FIG. 1 shows an embodiment of a superconducting accelerator tube and a method for manufacturing the same according to the present invention, and is a plan view of an accelerating tube arranged with an optical system and a chamber used for welding the superconducting accelerator tube.

FIG. 2 is a cross-sectional front view of the accelerator tube shown in FIG. 1.

FIG. 3 is a plan layout diagram of the optical system and chamber shown in FIG. 1;

FIG. 4 is a cross-sectional front view of a cell component in which half cells, which are components of the acceleration tube, are joined by a connecting member.

FIG. 5 is a side view showing a state in which the cell component shown in FIG. 4 is fixed with a jig.

6 is a view of the jig shown in FIG. 5 viewed from the direction of arrow VI; FIG.

7 is a view of the jig shown in FIG. 5 viewed from the direction of arrow VII; FIG.

FIG. 8 is a view of the jig shown in FIG. 5 as viewed from the direction of arrow VIII.

FIG. 9 is a front view showing a state in which a tubular body made up of a plurality of cell parts is integrated with a fastening band.

FIG. 10 shows a second embodiment of the method of the present invention, and is a partially sectional front view of a welding device used when manufacturing cell parts by welding components of a single cell acceleration tube.

FIG. 11 is a diagram illustrating a welded portion divided when cell parts are welded.

12 is a partially sectional front view showing a welding device used for welding cell parts manufactured by the welding device of FIG. 10; FIG.

FIG. 13 explains a third embodiment of the method of the present invention, and is a sectional front view of a cell component in which half cells are welded via a connecting member.

FIG. 14 is a cross-sectional front view of a cell component in which a half cell and a flange are welded together.

15 is a partially sectional front view showing a state in which a plurality of cell parts shown in FIGS. 13 and 14 are assembled and attached to a welding device. FIG.

16 is a partially sectional front view illustrating a fourth embodiment of the method of the present invention, showing a case where a plurality of cell parts are welded using an optical fiber in the welding apparatus shown in FIG. 15. FIG.

17 is an enlarged view of section XVII in FIG. 16. FIG.

18 is an enlarged view taken from the direction of arrow XVIII in FIG. 16. FIG.

FIG. 19 shows a fifth embodiment of the method of the present invention, and is a partially sectional front view in the case of welding abutted half cells by irradiating laser light from an optical fiber.

FIG. 20 shows a sixth embodiment of the method of the present invention, in which half cells are positioned with a positioning jig with cooling water flowing inside and welded by irradiating laser light from an optical fiber. It is a half-sectional front view.

FIG. 21 is a sectional view taken along section XXI-XXI in FIG. 20;

FIG. 22 is a perspective view showing a flange, which is one of the components, for explaining a conventional superconducting accelerator tube and its manufacturing method.

FIG. 23 is a perspective view showing a cell coupling component, which is one of the components.

FIG. 24 is a perspective view showing a half cell which is one of the components.

25 is a cross-sectional front view of a single cell accelerator tube manufactured using the components shown in FIGS. 22 and 24. FIG.

26 is a cross-sectional front view of a multi-cell accelerator tube manufactured using the components shown in FIGS. 22 to 24. FIG.

[Explanation of symbols]

10 Superconducting accelerator tube 11 Half cell (component) 11a Small diameter part (peripheral end) 11b Large diameter part (peripheral end) 12 Connecting member (component) 13 Flange (component)

Claims (17)

[Claims] 1. A superconducting acceleration tube formed by welding peripheral ends of a plurality of components made of superconducting materials to each other, wherein each of the peripheral ends is welded by a laser beam. . 2. The superconducting accelerator tube according to claim 1, wherein only the inner surface of each peripheral end portion of the superconducting accelerator tube is laser welded, and the welding depth is one-half or less of the thickness of the superconducting material. . 3. The superconducting accelerator tube according to claim 2, wherein the superconducting accelerator tube has a weld depth of 150 μm or more at each of the circumferential ends. 4. The superconducting accelerator tube according to claim 1, wherein the superconducting material has a thickness in a range of 0.1 mm or more and 1 mm or less. 5. The superconducting accelerator tube according to claim 1, wherein the outside of the superconducting accelerator tube is fixed by a jig. 6. Manufacture of a superconducting accelerator tube having circumferential ends that abut against each other, and in which a plurality of components made of superconducting material are laser welded to each other using a laser beam irradiated to the circumferential ends. Method. 7. The method of manufacturing a superconducting accelerator tube according to claim 6, wherein each peripheral end portion is laser welded only on the inner surface, and the welding depth is one-half or less of the thickness of the superconducting material. 8. Each of the peripheral edges has a welding depth of 15 mm.
The method for manufacturing a superconducting accelerator tube according to claim 7, wherein the thickness is 0 μm or more. 9. The method for manufacturing a superconducting accelerator tube according to claim 6, wherein the thickness of the superconducting material is in a range of 0.1 mm or more and 1 mm or less. 10. The method of manufacturing a superconducting accelerator tube according to claim 6, wherein the laser welding is performed in an inert gas atmosphere. 11. The superconducting accelerator tube is manufactured by welding peripheral ends of the plurality of components to each other in a vacuum.
A method for manufacturing a superconducting accelerator tube according to claims 6 to 9. 12. After spot-welding and temporarily attaching a plurality of locations of each peripheral end portion of the component parts that are abutted against each other,
The method for manufacturing a superconducting accelerator tube according to any one of claims 6 to 11, wherein the entire peripheral end portion is welded. 13. The method of manufacturing a superconducting accelerator tube according to claim 6, wherein the intensity of the laser beam during spot welding is set to 1/2 to 1/3 of the peak power. 14. Claims 6 to 12, wherein the pulse width of the laser beam during spot welding is set to 30% to 80% of the irradiation conditions when welding the entire peripheral edge.
The method for manufacturing the superconducting accelerator tube described above. 15. The superconducting accelerator tube according to claim 6, wherein the region to be welded is divided into two or more regions when welding the entire peripheral end portion, and a predetermined cooling time is provided during welding between each region. manufacturing method. 16. The method for manufacturing a superconducting accelerator tube according to claim 6, wherein the laser beam is a YAG laser. 17. The method of manufacturing a superconducting accelerator tube according to claim 6, wherein the laser beam is used in pulsed oscillation.