JP2000150198A - Manufacture of superconducting high frequency cavity and superconducting high frequency cavity manufactured thereby - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a manufacturing method for a superconducting high frequency cavity and a cavity manufactured by the method, capable of substantially reducing manufacturing cost and improving a radiation effect and mechanical strength. SOLUTION: A flame 3 is blown toward the external surface of a superconducting high frequency cavity body 1 from a flame spraying gun 2 for high-speed gas flame spraying or ultra-high speed gas flame spraying. In this state, while a metallic pulverized material 5 of good thermal conductivity is fed to the flame 3 through tubing 4 and melted, the external surface of the cavity body 1 is covered with a metallic coat 6 of good thermal conductivity.

Description

DETAILED DESCRIPTION OF THE INVENTION

The present invention relates to a method for manufacturing a superconducting high-frequency cavity and a superconducting high-frequency cavity manufactured by the method.

2. Description of the Related Art It is known that a superconducting high-frequency cavity can obtain an accelerating electric field that is at least one order of magnitude higher than that of a conventional normal-conducting high-frequency cavity, thereby enabling a compact accelerator. . However, in the case of such a superconducting high-frequency cavity, the entire cavity must be cooled to a very low temperature by a cooling medium such as liquid helium, so that the entire system becomes large and large. Further, if there is a micro defect at the time of manufacturing the cavity, heat is generated at the defective portion when actually used,
It can cause a disruption of the superconducting function called quench. In particular, niobium (Nb) is generally used as a thin superconducting material forming a superconducting high-frequency cavity.
Such niobium has poor thermal conductivity, and when heat is generated, heat does not diffuse quickly, so that quench is likely to occur. Therefore, conventionally, Japanese Patent Publication No. 7-112122,
JP-A-2-220400, JP-A-2-22039
As disclosed in, for example, Japanese Patent Application Laid-Open No. 9-209, a high thermal conductive metal such as copper (C
It has been considered that u) is formed into a thin film by stacking by physical vapor deposition (PVD), plasma spraying, and electroforming, thereby improving the heat radiation effect and increasing the generated electric field and magnetic field.

However, in these methods, a film is formed by a physical vapor deposition method in a vacuum, thermal spraying is performed in a non-oxidizing atmosphere in a vacuum, or a film is formed by electroforming. Therefore, there is a problem that expensive special devices and large-scale devices are required, and the manufacturing cost is significantly increased. The present invention has been made in view of the above circumstances, and a method and a method for manufacturing a superconducting high-frequency cavity capable of achieving a significant reduction in manufacturing cost, and further improving a heat radiation effect and mechanical strength. It is an object of the present invention to provide a superconducting high-frequency cavity manufactured by the same.

According to the first aspect of the present invention,
The present invention is characterized in that a metal film having good thermal conductivity is coated on the outer peripheral surface of a cavity body formed of a thin superconductor by high-speed gas flame spraying or ultra-high-speed gas flame spraying. According to a second aspect of the present invention, in the first aspect of the present invention, after the outer peripheral surface of the cavity body formed by the thin superconductor is coated with a metal film having good thermal conductivity, a deoxidation treatment is performed. Features. According to a third aspect of the present invention, in the first aspect of the invention, after the outer peripheral surface of the cavity body formed by the thin superconductor is coated with a metal film having good thermal conductivity,
Further, a superconducting material is laminated and coated on the outer peripheral surface of the metal coating by high-speed gas flame spraying or ultra-high-speed gas flame spraying. The invention according to claim 4 is the invention according to claim 1.
In the invention described in the above, after the outer peripheral surface of the cavity body formed by the thin superconductor is coated with a metal film having good thermal conductivity, deoxidation treatment is performed, and further, high-speed gas flame spraying is performed on the outer peripheral surface of the metal film. Alternatively, the method is characterized in that a superconducting material is laminated and coated by ultrahigh-speed gas flame spraying. According to a fifth aspect of the present invention, in the first aspect of the present invention, after the outer peripheral surface of the cavity body formed by the thin superconductor is coated with a metal film having good thermal conductivity, a deoxidation treatment is performed. After the superconducting material is laminated and coated on the outer peripheral surface of the metal film by high-speed gas flame spraying or ultra-high-speed gas flame spraying, deoxidation treatment is performed. According to a sixth aspect of the present invention, in the first aspect of the present invention, the cavity body formed of the thin superconductor is formed by bulging. According to a seventh aspect of the present invention, in the first aspect of the present invention, the cavity body formed by the thin superconductor is composed of a plurality of cylinders, and a joint between these cylinders is formed by an electron beam. It is characterized by being joined by welding. According to an eighth aspect of the present invention, in the first aspect of the present invention, the hollow body formed by the thin superconductor is composed of a plurality of cylinders, and a joining portion of these cylinders is defined by YA.
It is characterized by being joined by G laser welding. According to a ninth aspect of the present invention, in the invention according to any one of the first to eighth aspects, the hollow body formed by the thin superconductor is formed by connecting a plurality of cylindrical bodies whose peripheral surfaces are protruded in an arc shape. The thickness of the metal film having good thermal conductivity at the connecting portion of each cylindrical body is formed to be larger than the thickness of the metal film having good thermal conductivity at the portion protruding in an arc shape. . The invention according to claim 10 is characterized by a superconducting high-frequency cavity manufactured by the method according to any one of claims 1 to 9. As a result, according to the first aspect of the present invention, high-speed gas flame spraying or ultra-high-speed gas flame spraying can be performed in the atmosphere, so that equipment costs can be reduced and the process can be simplified. According to the second aspect of the present invention, oxides slightly remaining in the metal film having good thermal conductivity can be reliably removed. According to the third aspect of the present invention, the superconducting material is cooled to a very low temperature to be in a superconducting state, so that it is possible to have a shielding effect of preventing a phenomenon that an external magnetic field or electric field enters the cavity. According to the fourth aspect of the present invention, the oxide slightly remaining in the metal film having good thermal conductivity can be reliably removed, and an external magnetic field or an electric field penetrates into the cavity due to the superconducting state of the superconducting material. A shielding effect for preventing the phenomenon can be provided. According to the fifth aspect of the present invention, it is possible to reliably remove the oxide film slightly remaining in the metal film having good thermal conductivity and the superconducting material. According to the inventions described in claims 6 to 8, a superconducting high-frequency cavity main body that is appropriate in relation to the production amount and the manufacturing cost can be obtained. According to the ninth aspect of the present invention, the rigidity of the superconducting high-frequency cavity can be increased to improve the mechanical strength, and a strong configuration that does not deform even when an external pressure is applied can be realized. According to the tenth aspect of the present invention, it is possible to realize a significant reduction in the manufacturing cost and to improve the heat radiation effect and the mechanical strength.

Embodiments of the present invention will be described below with reference to the drawings. (First Embodiment) FIG. 1 is a view for explaining a first embodiment of a method for manufacturing a superconducting high-frequency cavity according to the present invention. In the figure, reference numeral 1 denotes a superconducting high-frequency cavity main body made of a thin superconductor such as niobium, and the cavity main body 1 is formed by connecting a plurality of (three in the illustrated example) cylinders whose peripheral surfaces are protruded in an arc shape. Things. Here, as a method of forming the cavity main body 1 formed of such a thin superconductor, the cavity main body 1 is formed by a hydraulic bulge process, and the components constituting the cavity main body 1, for example, the peripheral surface is protruded in an arc shape. What is obtained by joining the joints of the respective cylinders by electron beam welding,
The joint of each cylindrical body whose peripheral surface is formed in an arc shape is Y
One joined by AG laser welding is conceivable. What kind of processing method is adopted may be determined appropriately in relation to the production amount and the manufacturing cost.
A spray gun 2 for high-speed gas flame spraying or ultra-high-speed gas flame spraying is disposed toward the outer peripheral surface of the cavity body 1, and the outer peripheral surface of the superconducting high-frequency cavity main body 1 is provided by the spray gun 2. At the same time, a thin tube 4 is arranged toward the flame 3, and a powdery material 5 made of a metal having good heat conductivity is fed into the flame 3 through the thin tube 4. . From such a configuration, first, the cavity main body 1
The flame 3 is ejected from the spray gun 2 for high-speed gas flame spraying or ultra-high-speed gas flame spraying toward the outer peripheral surface of the cavity body 1 while rotating about the axis O. Further, in a state where the flame 3 is jetted, a metal material having good heat conductivity, for example, a powdery material of copper (Cu) is fed into the flame 3 through the thin tube 4 and melted. The metal film 6 having good thermal conductivity is coated while spraying. At this time, by moving one of the spraying gun 2 and the cavity body 1 in the direction of the axis O, it is possible to cover the metal film 6 having good thermal conductivity almost uniformly over the entire outer surface of the cavity body 1. it can. Therefore, according to such a method, the metal film 6 having good heat conductivity is used.
High-speed gas flame spraying or ultra-high-speed gas flame spraying is used for coating, but since these high-speed gas flame spraying or ultra-high-speed gas flame spraying can be performed in the atmosphere, conventionally used It does not need to be performed in a special environment such as in a vacuum or in a solution, as is the case with the conventional physical vapor deposition (PVD), plasma spraying, and electroforming film formation work, and is expensive and special equipment or large-scale equipment Therefore, the equipment cost can be reduced and the process can be simplified, whereby the production cost can be significantly reduced.
By coating the metal film 6 having good thermal conductivity over the entire outer periphery of the cavity body 1 by such high-speed gas flame spraying or ultra-high-speed gas flame spraying, the heat radiation effect is enhanced as a superconducting high-frequency cavity. And the generated electric field can be increased. Further, the superconducting material such as niobium constituting the cavity body 1 has low mechanical strength. Therefore, when the superconducting material is actually incorporated in an accelerator and used, the inside of the superconducting high-frequency cavity is evacuated and the whole is liquid. When immersed in helium, it is deformed by external pressure, which is not preferable from the viewpoint of the performance of the superconducting high-frequency cavity. However, as described above, when the metal film 6 having good thermal conductivity is laminated on the outside of the cavity main body 1 formed of the thin superconductor, the thickness of the superconducting high-frequency cavity increases, and the mechanical strength decreases. As a result, the heat radiation effect is improved, and in addition to the effect that the generated electric field can be increased, the effect that the mechanical strength can be improved can be expected. Furthermore, when the metal film 6 having good heat conductivity is laminated and coated on the outer peripheral surface of the cavity body 1 by high-speed gas flame spraying or ultra-high-speed gas flame spraying of the spray gun 2, only a small amount of May remain undesirably in the subsequent process as a superconducting high-frequency cavity, for example, in a process such as bonding. In such a case, the metal film 6 is formed. By heating the cavity body 1 in a vacuum furnace for a long time and performing deoxidation treatment, a superconducting high-frequency cavity exhibiting good characteristics can be formed. For the deoxygenation treatment, there is a well-known reduction method in a hydrogen furnace, and this method can also be used.
By the way, according to an experiment conducted by the present applicant, when copper is coated with a thickness of 1 mm as a metal having good heat conductivity, 400 mm is applied in a vacuum furnace.
When heated at about 3 ° C. for about 3 hours, the copper oxide in the metal coating 6 was decomposed, and a deoxidizing treatment could be performed. Furthermore,
When a metal with good thermal conductivity is coated by high-speed gas flame spraying or ultra-high-speed gas flame spraying, pores of several percent by volume may remain in the coating, but there are some characteristics of the superconducting high-frequency cavity. It does not become a hindrance, and when the superconducting high-frequency cavity is incorporated into the accelerator and actually used, the cavity is immersed in liquid helium, so that liquid helium enters the pores, and rather cools Can be expected to be improved. (Second Embodiment) FIG. 2 is a view for explaining a second embodiment of a method for manufacturing a superconducting high-frequency cavity according to the present invention. In this case, as shown in the figure, a metal film 6 having good thermal conductivity is formed on the outside of the cavity body 1 formed by the thin superconductor.
Is superposed on the outer peripheral surface of the metal coating 6 by high-speed gas flame spraying or super-high-speed gas flame spraying to form a superconducting high-frequency cavity. According to such a superconducting high-frequency cavity, when actually used in an accelerator, the entire superconducting high-frequency cavity is immersed in liquid helium. The superconducting state is brought into a superconducting state, so that a shielding effect for preventing a phenomenon in which an external magnetic field or electric field enters the inside of the superconducting high-frequency cavity can be provided. When the superconducting material 7 is further laminated and coated on the outer peripheral surface of the metal film 6 by high-speed gas flame spraying or ultra-high-speed gas flame spraying, an oxide slightly remains in the superconducting material 7 and this oxide is This may have an undesired effect in a post-process as a cavity, for example, in a process such as bonding. Therefore, also in this case, by heating the cavity body 1 coated with the superconducting material 7 in a vacuum furnace for a long time in a vacuum furnace and performing deoxidation treatment, it is possible to form a superconducting high-frequency cavity exhibiting good characteristics. it can. (Third Embodiment) FIG. 3 is a view for explaining a third embodiment of a method for manufacturing a superconducting high-frequency cavity according to the present invention. In this case, since the cavity main body 1 has a shape in which a plurality of cylindrical bodies whose peripheral surfaces are protruded in an arc shape are connected, the thickness of the metal film 8 having good thermal conductivity at the connecting portion of each cylindrical body. Say,
It is formed so as to be thicker than the thickness of the metal film 9 having good thermal conductivity at the portion protruding in an arc shape. This way,
Since the rigidity of the entire superconducting high-frequency cavity can be increased and the mechanical strength can be improved, a strong configuration that does not deform even when an external pressure is applied can be realized. In the above-described embodiment, the superconducting high-frequency cavity main body 1 has been described as a triple superconducting body in which three cylindrical bodies whose peripheral surfaces are protruded in an arc shape are connected.
The present invention can also be applied to a cavity body 1 employing a series or a series of nine.

As described above, according to the present invention, the manufacturing cost can be significantly reduced, and the heat radiation effect and the mechanical strength can be improved.

[Brief description of the drawings]

FIG. 1 is a diagram for explaining a method for manufacturing a superconducting high-frequency cavity according to a first embodiment of the present invention.

FIG. 2 is a view for explaining a method of manufacturing a superconducting high-frequency cavity according to a second embodiment of the present invention.

FIG. 3 is a diagram for explaining a method of manufacturing a superconducting high-frequency cavity according to a third embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Cavity main body 2 ... Spray gun 3 ... Flame 4 ... Narrow tube 5 ... Material 6 ... Metal coating 7 ... Superconducting material 8 ... Metal coating 9 ... Metal coating

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Masayuki Ito 2-4, Suehirocho, Tsurumi-ku, Yokohama-shi, Kanagawa Prefecture Inside the Toshiba Keihin Plant (72) Inventor Kazuhiro Ohara 1st Toshiba-cho, Fuchu-shi, Tokyo Toshiba Corporation Fuchu Plant (72) Inventor Tomoko Ota 2-4 Suehirocho, Tsurumi-ku, Yokohama-shi, Kanagawa Prefecture F-term in Toshiba Keihin Works Co., Ltd. 2G085 BA05 BE01 BE06 EA02 EA04 EA10

Claims (10)

[Claims] 1. A superconducting high-frequency cavity in which an outer peripheral surface of a cavity body formed by a thin superconductor is coated with a metal film having good thermal conductivity by high-speed gas flame spraying or ultra-high-speed gas flame spraying. Manufacturing method. 2. The superconducting high-frequency cavity according to claim 1, wherein after the outer peripheral surface of the cavity body formed by the thin superconductor is coated with a metal film having good thermal conductivity, deoxidation treatment is performed. The method of manufacturing the torso. 3. An outer peripheral surface of a cavity body formed of a thin superconductor is coated with a metal film having good thermal conductivity, and then an outer peripheral surface of the metal coating is subjected to high-speed gas flame spraying or ultra-high-speed gas flame spraying. 2. The method for manufacturing a superconducting high-frequency cavity according to claim 1, wherein the superconducting material is laminated and covered by the method. 4. An outer peripheral surface of a cavity body formed by a thin superconductor is coated with a metal film having good thermal conductivity, deoxidation treatment is performed, and high-speed gas flame spraying is performed on an outer peripheral surface of the metal coating. 2. The method for manufacturing a superconducting high-frequency cavity according to claim 1, wherein the superconducting material is laminated and coated by ultrahigh-speed gas flame spraying. 5. An outer peripheral surface of a cavity body formed of a thin superconductor is coated with a metal film having good thermal conductivity, deoxidation is performed, and high-speed gas flame spraying is performed on the outer peripheral surface of the metal film. The method for manufacturing a superconducting high-frequency cavity according to claim 1, wherein the superconducting material is laminated and coated by ultrahigh-speed gas flame spraying, and then deoxidation treatment is performed. 6. The method for manufacturing a superconducting high-frequency cavity according to claim 1, wherein the cavity body formed by the thin superconductor is formed by bulging. 7. The cavity body formed of a thin superconductor comprises a plurality of cylinders, and the joints of these cylinders are joined by electron beam welding.
7. The method for manufacturing a superconducting high-frequency cavity according to any one of claims 1 to 6. 8. A hollow body formed of a thin superconductor is composed of a plurality of cylinders, and a joint between these cylinders is formed by YAG.
The method for manufacturing a superconducting high-frequency cavity according to any one of claims 1 to 6, wherein the joining is performed by laser welding. 9. A hollow body formed by a thin superconductor is formed by connecting a plurality of cylinders each having a peripheral surface projecting in an arc shape, and a metal film having good thermal conductivity at a connection portion of each cylinder. 9. The superconducting high-frequency cavity according to claim 1, wherein the thickness is formed so as to be thicker than the thickness of the metal film having good thermal conductivity at a portion protruding in an arc shape. Method. 10. A superconducting high-frequency cavity manufactured by the method according to claim 1.