JPH07296998A - Resonance frequency adjusting tuner of high-frequency accelerating cavity - Google Patents

Abstract

PURPOSE:To provide a resonance frequency adjusting tuner for high frequency accelerating cavity for making RF contact between the tuner body and a tuning plunger without resorting to slide contacting. CONSTITUTION:Airtight bellows 5 are furnished to enable advancing and retreating a tuning plunger 3 while the vacuum condition in an accelerating cavity 10 is maintained, and at the periphery of the bellows 5, high frequency shield bellows 6 for making high frequency connections of the plunger 3 with the tuner body 2 are provided as an RF contact, which is to be installed for preventing the airtight bellows 5 from being influenced by the electromagnetic waves in the cavity 10. The high frequency shield bellows 6 are not of the conventional type with which high frequency connections are generated by slide contacting, but of a new type in which high frequency connections are maintained by a bellows construction expanding and contracting with the advancing/retreating motions of a tuning plunger 3, and therefore, it is free from generation of gas associate with slide contacting. fusion attachment of the contact, production of powder from machining, etc., and a stable and lasting effect of RF contact can be obtained.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a resonance frequency adjusting tuner for adjusting the resonance frequency of a high frequency acceleration cavity for accelerating charged particles by high frequency power.

[0002]

2. Description of the Related Art In a high frequency accelerating cavity, the frequency of the high frequency power to be used is designed to match the cavity resonance frequency determined by the shape of the cavity. However, there is a gap between the high frequency power frequency and the cavity resonance frequency due to a cavity manufacturing error, a cavity shape change due to temperature rise, and a reactance component due to beam loading, which must be corrected. In order to adjust this frequency shift, a resonance frequency adjusting tuner (hereinafter referred to as a tuner) is provided in the acceleration cavity. FIG. 3 is a cross-sectional view of the high-frequency acceleration cavity as seen from the downstream side in the beam acceleration direction. The high-frequency power input coupler 40, the high-order mode damper 41, the blind cover 42, and The tuner 30 is attached. The tuner 30 is of a plunger type that adjusts the resonance frequency by adjusting the amount of insertion of the cylindrical conductor into the acceleration cavity to change the inductance when the acceleration cavity is represented by an equivalent circuit. There is.
The resonance frequency adjustment by this tuner is automatically adjusted based on the information of the feedback circuit that detected the resonance frequency fluctuation.
The resonant frequency of the accelerating cavity is adjusted so that it always remains constant.

Tuner 30 adopted for the above purpose
FIG. 4 shows the configuration of a conventional example of the above. In FIG. 4, the tuner 30 is mounted on the tuner mounting port 32 formed on the outer periphery of the high frequency acceleration cavity 31 by using a vacuum flange 33. The tuner 30 drives the tuning plunger 34, which is arranged coaxially with the tuner mounting port 32, forward and backward through a plunger rod 35 by a driving means (not shown) provided in the tuner main body 36.
The resonance frequency of the acceleration cavity 31 is adjusted by adjusting the amount of insertion into the acceleration cavity 31. Since the inside of the acceleration cavity 31 is evacuated to vacuum, an airtight bellows 37 having an expansion and contraction structure is provided between the tuning plunger 34 and the tuner body 36 in order to maintain this vacuum state and shuts off the vacuum from the atmosphere. While allowing the tuning plunger 34 to move forward and backward. Further, since the electromagnetic wave in the acceleration cavity 31 is drawn into the tuner 30 due to the coaxial structure of the tuner 30, a voltage is generated in the airtight bellows 37. In order to prevent the occurrence of damage such as pinholes on the bellows 37 due to this generated voltage, the tip of each of the plurality of metal pieces 38 connected to the tuner body 36 and arranged so as to surround the circumference of the bellows 37 is prevented. Mounted contact 39
The electromagnetic contact is prevented from leaking into the airtight bellows 37 by an RF contact that makes a sliding contact with the tuning plunger 34 and connects the tuner body 36 and the tuning plunger 34 at a high frequency.

[0004]

In the above-mentioned conventional structure, since the RF contact between the tuning plunger 34 and the tuner main body 36, which are driven forward and backward, is made by sliding contact, there are the following problems. . (1) When carbon graphite is used as the contact 39 for sliding, gas generated by heat generation due to Joule loss due to high-frequency current is released into the accelerating cavity, and it becomes impossible to maintain high vacuum in the cavity. (2) Further, when a beryllium copper-based metal is used as the contact 39, the contact resistance becomes large, so that welding occurs at the contact portion when an excessive current flows, which hinders the driving operation of the tuning plunger. To give. (3) Since cutting powder is generated due to sliding contact of solids with each other, seizure or discharge of sliding parts easily causes detuning of the resonance frequency. An object of the present invention is to solve the above-mentioned problems with the conventional configuration by making RF contact between the tuner body and the tuning plunger without using sliding contact.

[0005]

[Means for Solving the Problems] The means adopted by the present invention in order to achieve the above object are as follows: a tuning plunger mounted inside the cavity of a high frequency accelerating cavity, a tuning plunger located inside the cavity, and a tuner located outside the cavity. The body is connected to the main body with a highly airtight and expandable airtight bellows, and the amount of insertion of the tuning plunger into the cavity is adjusted by driving the tuning plunger forward and backward with respect to the acceleration cavity. In a tuner for adjusting the resonance frequency of the high-frequency acceleration cavity for adjusting the resonance frequency of the high-frequency acceleration cavity, a high-frequency shield expandable and contractable in the direction of the tuning plunger for high-frequency connection between the tuning plunger and the tuner body on the outer peripheral side of the bellows. Resonant frequency of high-frequency accelerating cavity characterized by being provided with bellows It is configured as adjustment tuner.

[0006]

According to the present invention, the airtight bellows for enabling the tuning plunger to move forward and backward while maintaining the vacuum state in the acceleration cavity is provided in order to prevent the influence of the electromagnetic wave in the acceleration cavity. As an RF contact, a high-frequency shield bellows that provides a high-frequency connection between the tuning plunger and the tuner body is provided on the outer peripheral side of the airtight bellows. The high-frequency shield bellows is not conventionally used for high-frequency connection by sliding contact, but the high-frequency connection is maintained by the bellows structure that expands and contracts as the tuning plunger moves forward and backward. There is no generation, welding of contact points, generation of cutting powder, etc., and the effect of stable RF contact continues.

[0007]

Embodiments of the present invention will now be described with reference to the accompanying drawings to provide an understanding of the present invention. still,
The following embodiment is an example embodying the present invention,
It does not limit the technical scope of the present invention. here,
FIG. 1 is a cross-sectional view showing the configuration of a resonance frequency adjusting tuner of a high frequency accelerating cavity according to an embodiment of the present invention. Figure 2 (a)
(B) is a perspective view showing an example of composition of a high frequency shield bellows concerning an example. In FIG. 1, a resonance frequency adjusting tuner (hereinafter abbreviated as a tuner) 1 of a high frequency acceleration cavity according to the present embodiment is a mounting port provided on an outer contour of a high frequency acceleration cavity (hereinafter abbreviated as a cavity) 10. 11 is mounted using a vacuum flange structure. Tuner 1
The tuner main body 2 and a tuning plunger 3 that is driven back and forth by a drive means (not shown) provided on the tuner main body are mainly configured. By moving the tuning plunger 3 back and forth into the cavity 10, the cavity 10 is moved.
The resonance frequency is adjusted. The forward / backward driving of the tuning plunger 3 is performed by forward / backward driving of the tuning rod 7 fixed on the central axis of the tuning plunger 3 by a driving means provided in the tuner body 2. In the above configuration, the inside of the mounting cylinder portion 4 of the tuner 1 to the mounting port 11 is in a vacuum state because it communicates with the inside of the cavity 10. On the other hand, since the tuner body 2 side is in an atmospheric pressure state, the space between It is necessary to move the tuning plunger 3 back and forth while maintaining the airtight state. An airtight bellows 5 is arranged between the tuning plunger 3 and the tuner body 2 as the airtight holding means.

Further, since the mounting cylinder portion 4 has a coaxial structure centered on the tuning plunger 3, electromagnetic waves generated in the cavity 10 are drawn in. As a preventive measure against the occurrence of damage to the airtight bellows 5 such as pinholes due to the action of a flowing current, a voltage is generated in the airtight bellows 5 formed of a metal material by this electromagnetic wave, and an electromagnetic wave is applied to the outer circumference of the airtight bellows 5. A high-frequency shield bellows 6 is provided for shutting off. The high frequency shield bellows 6 can be configured as shown in FIGS. As shown in the figure, the high-frequency shield bellows 6 formed in a cylindrical shape with a metal material has its both ends fixed to the tuning plunger 3 and the tuner body 2, and expands and contracts in a bellows shape in accordance with the operation of the tuning plunger 3 driven forward and backward. Therefore, the electromagnetic wave is prevented from leaking into the airtight bellows 5 without hindering the forward / backward movement of the tuning plunger 3.

In the structure shown in FIG. 2 (a), the elasticity of the metal cylinder is kept flexible, and the gas in the tuner 1 is efficiently exhausted when the vacuum in the cavity 10 is exhausted. The opening 8 is provided all around. Since the opening diameter of the opening 8 is formed so as to be smaller than the cutoff wavelengths of the acceleration frequency and the main higher-order mode frequencies, the high frequency power is prevented from passing through the airtight bellows 5. Figure 2
In the configuration shown in (b), the metal tubular body is formed by the wire net 9. As shown in the drawing, the meshing direction of the wire net 9 is set to be an oblique direction with respect to the expansion / contraction direction to improve the elasticity and increase the opening area of the vacuum exhaust. Since the high-frequency shield bellows 6 having the above structure prevents the electromagnetic waves from leaking into the airtight bellows 5, there is no contact portion due to the sliding structure as in the conventional structure, and gas is generated by the sliding contact. No welding, welding, or generation of cutting powder.

[0010]

As described above, according to the present invention, the airtight bellows for enabling the tuning plunger to move forward and backward while maintaining the vacuum state in the acceleration cavity is affected by the electromagnetic wave in the acceleration cavity. As an RF contact provided to prevent the above, a high-frequency shield bellows that provides a high-frequency connection between the tuning plunger and the tuner body is provided on the outer peripheral side of the bellows. The high frequency shield bellows is not conventionally used for high frequency connection by sliding contact, but the high frequency connection is maintained by the bellows structure which expands and contracts as the tuning plunger moves forward and backward. There is no generation, no welding of contact points, no generation of cutting powder, etc., and the effect of stable RF contact is maintained.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing the configuration of a resonance frequency adjusting tuner of a high-frequency acceleration cavity according to an embodiment of the present invention.

FIG. 2 is a perspective view showing a configuration of a high frequency shield bellows according to an embodiment.

FIG. 3 is a sectional view showing how the tuner is attached to the high-frequency acceleration cavity.

FIG. 4 is a sectional view showing a configuration of a resonance frequency adjusting tuner according to a conventional example.

[Explanation of symbols]

 1 ... Tuner for adjusting resonance frequency 2 ... Tuner body 3 ... Tuning plunger 5 ... Airtight bellows 6 ... High frequency shield bellows 10 ... High frequency accelerating cavity 11 ... Mounting port

Claims (1)

[Claims] 1. A high-airtight and expandable airtight bellows is connected between a tuning plunger mounted inside the outer periphery of the high-frequency acceleration cavity and arranged inside the cavity and a tuner body arranged outside the cavity. At the same time, by adjusting the amount of insertion of the tuning plunger into the cavity by driving the tuning plunger forward and backward with respect to the acceleration cavity, the resonance frequency of the high frequency acceleration cavity is adjusted. In the tuner, for adjusting the resonance frequency of a high-frequency accelerating cavity, a high-frequency shield bellows is provided on the outer peripheral side of the bellows, the high-frequency shield bellows extending and contracting in the direction of the tuning plunger for high-frequency connection between the tuning plunger and the tuner body. Tuner.