JPH0378302A - High frequency acceleration cavity - Google Patents

Abstract

PURPOSE:To suppress the temperature rise of a flexible connection body and to attain the input of large power by providing the entrance and exit of cooling water for permitting cooling water to flow into an area surrounded by means of the flexible connection body and a flexible board. CONSTITUTION:The outer peripheries of a guide flange 10 and an acceleration electrode 3a are welded through the flexible board 21. The cooling water entrance 22 and the cooling water exit 23 are provided in space surrounded by the flexible connection body 9 and the flexible board 21 and cooling water is permitted to flow. Thus, the flexible connection body 9 can directly be cooled, the temperature rise of the flexible connection body 9 is suppressed low and the input of large power is attained by permitting cooling water to flow into space surrounded by the flexible connection body 9 and the flexible board 21. Since the flexible board 21 has flexibility, a clearance DELTA between the acceleration electrodes 3a snd 3b becomes variable and a resonance frequency can be adjusted.

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Industrial Application Field) The present invention relates to a high frequency acceleration cavity used in an accelerator used in VLSI microfabrication and the like.

(Prior technology) Accelerators are used to accelerate beams of electrons, protons, ions, etc. to high energy states, and they emit synchrotron radiation (SOR) when bending the beam's trajectory by applying a magnetic field.
Light (also called light) is about to be applied to new fields such as ultra-LSI microfabrication (lithography).

The accelerator is provided with a high-frequency acceleration cavity that supplies high-frequency energy to electrons in order to accelerate the electrons and replenish energy lost due to SOR light.

Although there are various types and resonance frequencies of high-frequency acceleration cavities, a semi-coaxial acceleration cavity will be explained here as an example.

Figure 2 shows an example of a conventional high-frequency acceleration cavity, where 1 is an outer cylinder and 2 is an example of a conventional high-frequency acceleration cavity.
is a side plate, and 3a and 3b are a pair of accelerating electrodes that penetrate the side plate 2 and are arranged in series in the axial direction with a predetermined gap Δ.

Reference numeral 9 denotes a flexible connector, the electrode 3a is connected to the side plate 2 via the flexible connector 9, and the electrode 3b is directly fixed to the side plate 2.

An antenna 4 for supplying high frequency energy into the cavity is attached to the outer cylinder 1, and is connected to a high frequency power source (not shown). Further, 5 is a tuner for adjusting the resonance frequency of the cavity. The inside of the cavity is maintained at a high vacuum of 10-9 Torr or more, similar to the beam duct 6 connected to the accelerating electrodes 3a and 3b. For this purpose, a gasket 8 is attached to the joining surface of each member.

is an integer multiple of

Here, C is the capacitance of the cavity, L is the inductance, and C is determined by the gap Δ between the pair of accelerating electrodes 3a and 3b. However, it is difficult to manufacture a device so that the resonance frequency matches the designed value, and it also changes due to temperature rise during operation, deformation due to external pressure, etc. The tuner 5 is provided to adjust the deviation of the resonance frequency due to such factors. When the tuner 5 is inserted, L becomes small and the resonance frequency increases, and when the tuner 5 is removed, the resonance frequency decreases.

When the manufacturing error is not within the adjustment range of the tuner 5, the gap Δ between the accelerating electrodes 3a and 3b is adjusted. That is, as Δ increases, the capacitance C decreases and the resonant frequency increases, and as Δ decreases, the resonant frequency decreases. For this reason, the flexible connecting body 9 must be flexible, and since the flexible connecting body 9 also serves as a vacuum wall, it must be completely vacuum sealed with the accelerating electrode 3a and the side plate 2 by welding or the like. There must be.

An adjustment flange 12 is attached to the accelerating electrode 3a, and a guide flange 10 is attached to the side plate 2. By adjusting the distance between these two flanges with the adjusting screw 11 and lock nut 13, the accelerating electrodes 3a, 3b
Let the gap Δ be a predetermined value. In addition, the side plate 2 and the outer cylinder 1
A cooling hole 14 is provided for cooling.

(Problems to be Solved by the Invention) In a high frequency acceleration cavity having such a configuration, the flexible connector 9 must be thin in order to have the necessary flexibility.

On the other hand, a high frequency current flowing from the accelerating electrode 3a to the side plate 2 passes through the flexible connector 9, and a large amount of heat is generated. The heat generated by the flexible connecting body 9 is cooled down by the cooling holes 14 in the same way as the side plate 2, but as mentioned above, the flexible connecting body 9 is thin and not only does not have enough heat conduction area, but also has a large distance from the cooling holes 14. This causes a large temperature rise. As a result, large high-frequency power cannot be input, and an abnormal temperature rise in the flexible connector 9 increases the amount of released gas, causing vacuum deterioration.
There are many problems with reliability.

Therefore, the present invention provides a high-performance and highly reliable high-frequency acceleration cavity that suppresses the temperature rise of the flexible connecting body, which is a problem with conventional high-frequency acceleration cavities, and is capable of inputting large amounts of power. The purpose is to

[Structure of the invention] (Means for solving the problem) In order to achieve the above object, the present invention provides a guide flange 1.
0 and the outer periphery of the accelerating electrode 3a are welded together via a flexible plate 21. A cooling water outlet 22 and a cooling water outlet 23 are provided in a space surrounded by the flexible connector 9 and the flexible plate 21 to allow cooling water to flow.

(Function) As described above, the flexible connecting body 9 can be directly cooled by flowing cooling water into the space surrounded by the flexible connecting body 9 and the flexible plate 21. Temperature rise can be suppressed to a low level and large power input is possible. Since the flexible plate 21 is flexible, the gap Δ between the accelerating electrodes 3a and 3b can be changed as in the conventional example, and the resonance frequency can be adjusted.

(Example) Hereinafter, an example of the present invention will be described using FIG. 1. In the longitudinal sectional view of FIG. 1, 1 is an outer cylinder, and 2 is a side plate, the outer periphery of which is hermetically connected to the outer cylinder 1 with a bolt 15 via a gasket 8.

Accelerating electrodes 3a and 3b are inserted into the inner peripheral side of the side plate 2. Note that 4 is an antenna for supplying high frequency energy into the cavity, and 5 is a tuner for adjusting the resonance frequency.

The inside of the side plate 2 and the outer periphery of the accelerating electrode 3a are completely vacuum-sealed via a flexible connector 9. Further, the guide flange lO and the outer periphery of the accelerating electrode 3a are welded via a flexible plate 21. A cooling water outlet 22 and a cooling water outlet 23 are provided for flowing cooling water into a space surrounded by the flexible connector 9 and the flexible plate 21.

Next, the operation of the high frequency acceleration cavity configured as described above will be explained. If a large shift in resonance frequency occurs that cannot be fully adjusted by the tuner 5, the gap Δ between the accelerating electrodes 3a and 3b is changed to correct the shift in resonance frequency. As Δ increases, the resonant frequency increases, and conversely, as Δ decreases, the resonant frequency decreases. The gap Δ is adjusted by adjusting the distance between the adjusting flange 12 attached to the accelerating electrode 3a and the guide flange 910 attached to the side plate 2 using the adjusting screw 11 and the lock nut 13.

The flexible plate 21 welded between the guide flange 10 and the outer periphery of the accelerating electrode 3a is flexible, so it does not interfere with the adjustment of the gap Δ, and forms a cooling passage, allowing the cooling water to flow through the cooling water population. 22. By letting the cooling water enter and exit through the cooling water outlet 23, heat generated by the flexible connector 9 can be efficiently removed. In addition,
Unlike the flexible connector 9, no high-frequency current flows through the flexible plate 21, so no heat is generated, and the material may be non-conductive.

[Effects of the Invention] As explained above, according to the present invention, the flexible connecting body 9 can be directly and efficiently cooled with water, so the limit of input power due to the temperature rise of the flexible connecting body 9 can be greatly reduced. This enables high power input. Furthermore, an increase in the amount of gas released due to abnormal heat generation is suppressed, and a high-performance high-frequency acceleration cavity can be provided.

[Brief explanation of drawings]

FIG. 1 is a partially cutaway elevational view showing an embodiment of a high frequency acceleration cavity for an accelerator according to the present invention, and FIG. 2 is a sectional view showing a conventional high frequency acceleration cavity.

Claims (1)

[Claims] an outer cylinder; side plates attached to both open ends of the outer cylinder;
A pair of accelerating electrodes that penetrate this side plate and are arranged in series in the axial direction with a predetermined gap, and a flexible electrode that electrically connects the outer periphery of this accelerating electrode and the inner periphery of the side plate to form a vacuum boundary. It consists of a connecting body, a flexible plate that connects the guide flange attached to the side plate, and the outer periphery of the accelerating electrode, and for flowing cooling water into an area surrounded by the flexible connecting body and the flexible plate. A high frequency acceleration cavity characterized by having a cooling water inlet and an outlet.