JPH04118900A - Fixing structure for drift tube - Google Patents

Abstract

PURPOSE:To let the whole of main functions such as vacuum seal, electrical contact, positioning a drift tube and the like come into being by forming the tip end section of a stem with a conductive tapered section, and thereby concurrently boring a tapered hole onto a tank, which is identical in taper to the tapered section. CONSTITUTION:The tip end section of a stem 4a is formed with a tapered section 4b having the tapered surface of No.3 morse with high accuracy. And a tapered hole la which is identical in taper to the tapered section 4b, is bored onto the drift tube mounting section of a tank 1 with high accuracy. When the tapered section 4b is inserted into the tapered hole 1a, and when a drift tube 4 is then pulled up while the rotating position of the drift tube 4 is being aligned, the drift tube 4 is thereby firmly fixed onto the tank 1 by a wedge effect between the tapered section 4b and the tapered hole 1a.

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Utilization Public Funds> The present invention relates to a drift tube fixing structure, and is useful when applied to a drift tube type accelerator.

<Conventional technology> The drift tube type acceleration wave is shown in Fig. 3(a).

(As shown in bl, when the microwave 2 is supplied into the vacuum cavity resonance Wi (hereinafter referred to as tank) 1, the accelerating electric field generated by the resonance of the microwave 2 A drift tube 4 is arranged with high precision in the axial direction of the tank 1 so that the drift tube 4 can be accelerated in synchronization with the speed of the ion beam (for example, protons) 3 that is implanted into the tank 1. That is, the drift tube 4 has its stem 4a
It is suspended from the inner circumferential surface of the tank 1 via. At this time,
Vacuum sealing, electrical contact (RF contact), and positioning and fixing of the drift tube 4 are performed by providing separate elements with respective roles.

To further comment, as shown in Figure 4 Ta) and (b),
Vacuum sealing is achieved by an O-ring 5 and electrical contact; positioning and fixing of the copper plate 6 and drift tube 4 is achieved by a threaded adjustment mechanism 7 provided outside the tank 1. Therefore, in the prior art, the stem 4a and the tank 1 through which the stem 4a penetrates are
A gap 8 is provided between the holes 1a formed in the holes 1a.

<Problem to be solved by the invention> In the case of a drift tube type accelerator according to the prior art, when the size of the tank 1 which is an acceleration space becomes small, the distance between adjacent drift tubes 4 arranged in the tank 1 As a result, there is a problem in that it may become impossible to obtain a space for a vacuum seal, a space for providing an electrical contact, and a space for providing a mechanism for positioning and fixing the drift tube 4.

SUMMARY OF THE INVENTION In view of the above-mentioned prior art, it is an object of the present invention to provide a drift tube fixing structure that can realize all of the main functions such as vacuum sealing, electrical contact, and drift tube positioning.

Means for Solving the Problems> The present invention that achieves the above object is a fixed structure of a drift tube that is suspended from the inner peripheral surface of a conductive tank into the inside of the tank via a stem. A conductive tapered part was formed at the tip of the stem, a tapered hole with the same slope as the tapered part was formed in the tank, and the drift tube was fixed by fitting the tapered part into the tapered hole. Features.

According to the present invention having the above configuration, simply by inserting the tapered portion of the stem into the tapered hole of the tank, the tapered surface and the tapered hole are brought into close contact and a vacuum seal is applied, and at the same time, the electrical connection between the stem and the tank is Contact and drift tube positioning is performed.

Embodiments Hereinafter, embodiments of the present invention will be described in detail based on the drawings. Note that parts that are the same as those in the prior art are given the same numbers and redundant explanations will be omitted.

As shown in FIG. 1(al) to FIG. 1(Q), the stem 4a
A tapered portion 4b having, for example, a No. 3 Morse tapered surface is machined with high precision at the tip. In the drift tube mounting portion of the tank 1, a tapered hole 1a having the same slope as the tapered portion 4b is machined with high precision. In this way, the drift tube 4 can be assembled into a tank by inserting the tapered part 4b of the stem 4a into the tapered hole 1a, aligning the rotational position of the drift tube 4, and pulling up the drift tube 4 due to the wedge effect between the tapered part 4b and the tapered hole 1a. 1 is firmly fixed. That is, vacuum sealing, electrical contact and drift tube positioning are achieved simultaneously.

As described above, when the drift tube 4 is fixed by bringing the tapered portion 4b of the stem 4a into contact with the tapered hole 1a, fusion occurs at the tapered portion 4b. Therefore, if you do not consider replacing the drift tube 4, [you can leave it as it is, but
When considering replacement, the configuration is as shown in the following embodiment.

That is, as shown in FIG. 2, a different metal is plated or vapor-deposited on the tapered portion 4b.

In the case of B, as shown in Fig. 2, the hard metal 4c (N-barrel, nickel, platinum, etc.) is applied to the upper part of the tapered part 4b, and the soft metal (for example, indium, gold, etc.) is applied to the lower part of the tapered part 4b. , aluminum) 4d, only the hard metal 4C or only the soft metal 4d may be applied.

The hard metal 4C allows the tapered portion 4b to be attached and detached many times without fusion. If there is a scratch on the surface of the tapered part 4b and/or if the shape of the tapered part 4b is deformed, the soft metal 4d flows into the gap between the taper hole 1a and the taper hole 1a formed by the scratch or deformation, and becomes an auxiliary material. This creates a vacuum seal.

Note that the hard metal 4C and/or the soft metal 4d may be applied to the tapered hole 1a.

In the second embodiment described above, the relationship between the tapered portion 4b and the tapered hole 1a is the same as the effect of a wedge, so that it can be pushed in with a small force and is supported with a large force by the frictional force. The position of assembled objects is determined by their geometric shape.

At this time, the higher the shape accuracy of the taper, the better the position accuracy. Further, the more the surface roughness of the taper is improved, the better the vacuum sealing performance is. Since both the taper shape and the surface roughness depend on the processing capacity (accuracy) of the processing machine, it is advantageous to apply soft metal 4d, including the meaning of precision interpolation. It is only necessary to reduce the resistance of the taper, so the taper increases the contact surface and increases the pressure on the contact surface due to the wedge effect, ensuring more effective contact than before.The application of soft metal 4d with good conductivity is It is advantageous from this point of view as well.The application of hard metal 4c is advantageous in terms of preventing fusion.However, if the taper processing accuracy is high, hard metal 4c can be applied to the entire surface of the tapered part for reuse. <Effects of the Invention> As specifically explained in conjunction with the embodiments, the present invention provides for main functions such as vacuum sealing, electrical contact, and positioning of the drift tube. Since all of this can be achieved by fitting the tapered portion and the tapered hole, the degree of freedom in mounting the drift tube increases, resulting in an economical mounting structure.

Incidentally, the assembled accelerator will be used for more than 10 years, but unlike the conventional technology, the present invention does not use an O-ring and supports the drift tube on a wide surface, so there is no influence of radiation caused by microwaves and drift. Displacement of the drift tube position due to aging of the tube fixing part can be almost ignored. Conventionally, regular inspections of alignment accuracy were required once every year or every two years.

[Brief explanation of the drawing]

FIG. 1 is an assembly diagram showing the embodiment of the present invention in cross section;
Fig. 1 (bl is a longitudinal sectional view thereof, Fig. 1 tc) is a transverse sectional view thereof, Fig. 2 is an enlarged front view showing a part of another embodiment of the present invention on an enlarged scale, and Fig. 3 (a ) and FIG. 3(b) are explanatory diagrams showing the principle of the drift tube type accelerator, and FIG. 4(al
4(b) is a cross-sectional view showing the prior art, and FIG. 4(b) is a vertical cross-sectional view showing a portion thereof. In the drawings, 1 is a tank, 1m is a tapered hole, 4 is a drift tube, 4a is a stem, and 4b is a tapered part. Patent application Mitsubishi Heavy Industries agent

Claims (1)

[Claims] A fixing structure for a drift tube that is suspended from the inner circumferential surface of a conductive tank into the inside of the tank via a stem, in which a conductive tapered part is formed at the tip of the stem, and A fixing structure for a drift tube, characterized in that a tapered hole having the same slope as the tapered part is formed in the tank, and the drift tube is fixed by fitting the tapered part into the tapered hole.