JPH0821477B2 - High frequency acceleration cavity manufacturing method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application] The present invention relates to a method of manufacturing a high-frequency acceleration cavity used for an accelerator such as an electron synchrotron and an electron storage ring.

(Prior Art) An accelerator is for accelerating a charged particle beam of electrons, protons, ions, etc. to a high energy state of several million electron volts (several MeV) to several tens of billions of electron volts (several tens of GeV). However, examples of this accelerator include an electron synchrotron and an electron storage ring.

A high frequency acceleration cavity is a device for giving energy to and accelerating charged particles in an accelerator. In the high frequency acceleration cavity, a high electric field of high frequency of several tens of megahertz to several gigahertz synchronized with the velocity of charged particles is generated by resonance, and the charged particles are accelerated by this high frequency electric field.

There are various types of high-frequency accelerating cavities, but Fig. 5 shows an example of a conventional multi-connection high-frequency accelerating cavity, in which multiple cavities (1) are connected to reduce the installation space. Then, the case of three stations is shown. The cavity (1) is the outer cylinder (2),
It is formed by joining the end plate (3) and the partition wall (4) at the joining portion (5a). The outer cylinder (2), the end plate (3), and the partition wall (4) are made of, for example, oxygen-free copper having excellent electric conductivity and thermal conductivity. The end plate (3) and the partition (4) are provided with a beam port (6) and a circular hole (7) through which the charged particle beam passes.

The high frequency power is input from the antenna (8), and the resonance frequency of the cavity (1) is finely adjusted by the tuner (9). The cavity (1) is connected to the accelerator through the flange (10), and a vacuum is drawn from the exhaust port (11) to maintain a high vacuum.

Due to the skin hardening, the inner surface of the cavity (1) smoothly passes a high-frequency current flowing through a very thin layer of a metal surface, which is called a few micrometers, so that the surface roughness is finished to a few micrometers or less. In order to reduce the increase in the electric resistance value due to work hardening, the final finishing process should be done in a small amount.

At the joint portion (5a), it is necessary to maintain the strength of the cavity (1), seal the vacuum, and allow a high-frequency current to flow smoothly. Conventionally, for example, as shown in FIGS. 6 and 7 of the enlarged view of the joint, welding is performed at the electron beam welded portion (5b) and the vacuum brazing welded portion (5c), and the joint is visually confirmed. In electron beam welding, the welding layer (2a) that reaches near the inner surface of the outer cylinder (2) is formed and joined by electron beam irradiation from the outside of the cavity. In the brazing welding part (5c), a silver brazing material that melts at a high temperature of about 800 ° C is placed in the joining part, and a brazing groove (2b) or the like is provided.
This also confirmed the joint visually.

In addition, according to the microfilm photographed of the contents of the specification and drawings attached to the application of Japanese Utility Model Application No. 47-021411 (Japanese Utility Model Application No. 48-096400), the high-frequency accelerating cavity is divided and manufactured.
A method of manufacturing a high frequency accelerating cavity joined by diffusion joining is described.

(Problems to be Solved by the Invention) In a high frequency accelerating cavity, it is desired to reduce the electric resistance of the inner surface of the cavity as much as possible to reduce heat generation due to a high frequency current and improve power efficiency.

The smooth finish of the surface without using a material having excellent electrical conductivity is to increase the power efficiency of the cavity. Therefore, it is desirable that the junction also has a sufficiently low electric resistance with respect to a high frequency current.

In the above-mentioned electron beam welding, since the molten layer (2a) that reaches the inner surface of the cavity is formed by the electron beam irradiation from the outer side of the cavity to join, the incident energy due to the electron beam is large, and therefore the molten metal Solidified,
There are drawbacks that deformation occurs when the temperature returns to room temperature, and it is difficult to form a molten layer uniformly near the surface. Also, in silver brazing on one side, a silver brazing filler metal is sandwiched between the joints to raise the temperature to a high temperature of about 800 ° C in a vacuum or atmosphere, but in this case, the silver brazing filler metal is used when the cavity is used. Since it was used in a vacuum, there was a defect that it was partly released as a release gas.

In addition, in the last-mentioned diffusion bonding, since the bonding part is exposed at least toward the inside during bonding, there is the drawback that the liquid layer flows out into the cavity during liquid phase diffusion bonding and the bonding becomes incomplete. It was

The present invention, as a countermeasure against these drawbacks, eliminates residual stress and prevents deformation, and the liquid phase does not flow out even in the liquid phase diffusion bonding in which the bonding portion melts during the bonding. It is an object of the present invention to provide a method of manufacturing a high frequency acceleration cavity in which a joint portion is formed as an alloy layer having high conductivity and less emitted gas.

[Structure of Invention]

(Means for Solving the Problem) In order to achieve the above object, in the present invention, a cavity is divided and manufactured, a joint is engaged in a U shape or an I shape, and a cavity is formed at the bottom of the joint. A metal foil made of a material having a melting point equal to or lower than that of the body material is sandwiched and bonded by diffusion bonding.

(Working) Cu is mainly used as the cavity material, but a metal foil of Ti, Sn, etc., which has a melting point equal to or lower than that of Cu, is used as the bonding surface at the bottom of the U-shaped or I-shaped engaging portion. Since the diffusion bonding is sandwiched between them, even if it is not visible, the metal foil becomes the liquid phase not only in the solid phase but also in the liquid phase diffusion bonding. Secure. Therefore, the present invention is a method of manufacturing a high-frequency acceleration cavity in which residual stress due to bonding is eliminated even if it cannot be visually confirmed, deformation is prevented, and a bonded portion is formed as an alloy phase having high conductivity and less emitted gas.

(Example) Example 1 Hereinafter, a first example of the present invention will be described with reference to FIGS. 1 and 2.

In this embodiment, three, five, and seven stations are connected, but here, three cavities (1) are connected to form one high-frequency acceleration cavity. (2) is a hollow cylindrical outer cylinder, (3) is a disk-shaped end plate diffusion-bonded to the outer cylinder (2), (3a) is a nose, (4) is a plurality of cavities (1) A disk-shaped partition wall for partitioning. The partition wall (4) is also joined to the outer cylinder (2) by diffusion joining. Both the end plate (3) and the partition wall (4) have a circular hole (7) at the center, and the beam passes through the center of this circular hole (7). (8) is an antenna for supplying high-frequency energy into the high-frequency acceleration cavity, which is attached to the outer cylinder (2) and is connected to a high-frequency power source (not shown). Energy must be transferred from one antenna (8) to all three cavities (1), and if the energy transfer is insufficient, the partition (4) is slotted into the cavities (1). In some cases, the number of bonds between them is increased. Reference numeral (9) is a cylindrical tuner for adjusting the resonance frequency of the cavity (1), and one tuner is provided for each cavity (1). (10) is a flange, (11) is a waste port, and as shown in FIG. 2, the outer cylinder (2) and the partition wall (4) are connected in the same direction with a U-shaped anchor, and A metal foil (12) is sandwiched between the bottoms of the joints, an outer cylinder is erected, and diffusion welding is performed.

 Next, the operation of the first embodiment will be described.

The reason why the fittings of the anchors are aligned in the same direction is that if the cavity (2) is set up and the diffusion bonding of the liquid phase is performed, the molten metal foil will not flow out and reliable bonding can be achieved. is there. That is, the metal foil (12) has a melting point equal to or lower than that of the material of the cavity (2),
First, the metal foil (12) becomes a liquid phase, and the diffusion bonding of the liquid phase forms an alloy layer around the bonded portion. Therefore, even if the bonded state cannot be visually observed, the metal foil (12) is reliably integrated and a vacuum is secured. Therefore, by eliminating the residual stress due to bonding and preventing deformation, and by forming the bonding part as an alloy layer with high conductivity and less emitted gas and making multiple connections, it is possible to ensure a flat electric field distribution with high power efficiency. And a method of manufacturing a high frequency acceleration cavity having excellent high frequency characteristics.

Embodiment 2 FIG. 3 shows the essential parts of the second embodiment. This is done by arranging the joints sandwiching the metal foil (12) in opposite directions to each other.
It is in the shape of a letter, and the others are as in the first embodiment.

If solid phase diffusion bonding is used even in this way, metal foil (12)
Does not flow out, and the same effect as that of the first embodiment can be obtained.

Embodiment 3 FIG. 4 shows a third embodiment. This is the same as the first embodiment except that only one cavity (1) is provided, while the cavity (1) of the first embodiment is multi-connected.

By doing so, the generated energy is reduced, but the action and effect according to the first embodiment can be obtained.

The joint portion (5) of the third embodiment may conform to that of the second embodiment.

〔The invention's effect〕

As described above, according to the present invention, the cavity is divided and manufactured, and the joint is formed in a U shape or an I shape, and the bottom of the joint has a melting point equal to or higher than that of the cavity material. Since metal foil of low material is sandwiched and connected by diffusion bonding, solid-phase or liquid-phase diffusion bonding surely forms an alloy layer around the bonded part even if it is not visible, and it is integrated and secures a vacuum. . Therefore, the present invention provides a method for manufacturing a high-frequency acceleration cavity in which residual stress due to bonding is eliminated, deformation is prevented, and a bonded portion is formed as an alloy layer having high conductivity and less emitted gas.

[Brief description of drawings]

FIG. 1 is a longitudinal sectional view showing a high frequency accelerating cavity manufactured by the method of the first embodiment of the present invention, FIG. 2 is an enlarged view of a main part of FIG. 1, and FIG. 3 is a second embodiment. 2 is a sectional view showing a portion corresponding to FIG. 2 manufactured by the method of FIG. 4, FIG. 4 is a vertical sectional elevation view of an upper half portion showing a high frequency acceleration cavity manufactured by the method of the third embodiment, and FIG. FIG. 6 is a vertical cross-sectional view showing a high-frequency acceleration cavity manufactured by the example method, and FIGS. 6 and 7 are cross-sectional views showing joints manufactured by the different methods of FIG. 1 ... cavity, 2 ... outer cylinder, 3 ... end plate, 5 ... joint, 12 ... metal foil.

Claims (1)

[Claims] 1. A method of manufacturing a high frequency accelerating cavity in which a cavity is formed of a conductive metal, a high frequency power is input, and charged particles are accelerated by an electric field generated, the cavity is divided and manufactured, and a joint is formed. Engage with a U-shaped or 1-shaped anchor,
A method of manufacturing a high-frequency acceleration cavity, characterized in that a metal foil made of a material having a melting point equal to or lower than that of a cavity material is sandwiched at the bottom of the joint, and the layers are bonded by diffusion bonding.